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Walden University. College of Health Sciences. This is to certify that the doctoral dissertation by. Gerard H. Famby has been found to be complete and ...
Walden University College of Health Sciences

This is to certify that the doctoral dissertation by

Gerard H. Famby

has been found to be complete and satisfactory in all respects, and that any and all revisions required by the review committee have been made.

Review Committee Dr. Diane Neal, Committee Chairperson, Public Health Faculty Dr. Aimee Ferraro, Committee Member, Public Health Faculty Dr. Scott McDoniel, University Reviewer, Public Health Faculty

Chief Academic Officer Eric Riedel, Ph.D.

Walden University 2013

Abstract Predictors of Community-Acquired Staphylococcus aureus Among U.S. Military Academy Cadets by Gerard H. Famby

MBA, American Intercontinental University, 2007 BS, City University of New York, New York, 1994

Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Health Sciences

Walden University May 2013

Abstract The prevalence and risk factors for community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), an emerging pathogen, remain a public health concern and warrant further studies. Since 2005, cases of MRSA skin infections have been observed at a military academy. This retrospective cohort study used multiple approaches based on the epidemiologic triangle to evaluate laboratory-confirmed MRSA cases to ascertain the prevalence and risk factors for CA-MRSA colonization among cadets at the academy. Historical data were obtained from an infection control nurse at an army community hospital. Environmental data were collected from 2 Barracks, A and B, and a fitness center. Poisson regression was used to compare the rates of disease between 4th-class (new) cadets and other classes of cadets (3rd, 2nd, and 1st class), chi-square analysis was used to identify sources of infection, and logistic regression was used to evaluate the effect of seasonality on the rates of the infection. Results indicated that 4thclass cadets were 23.15 times more likely to experience CA-MRSA infection, Barrack A was a significant source of infection, and Summer season was significantly associated with CA-MRSA infection among cadets. This research promotes positive social change by establishing a specific source of infection and identifying the most vulnerable class of cadets. The military academy could formulate policies or effective preventive measures to reduce the infection rate. Further research is needed to understand the role of summer initial training activities in CA-MRSA infections at this particular military academy.

Predictors of Community-Acquired Staphylococcus aureus Among U.S. Military Academy Cadets by Gerard H. Famby

MBA, American Intercontinental University, 2007 BS, City University of New York, New York, 1994

Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Health Sciences

Walden University May 2013

UMI Number: 3555191

All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion.

UMI 3555191 Published by ProQuest LLC (2013). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code

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Dedication I dedicate my dissertation to my wonderful wife, daughters, and son. They encouraged me to stay the course and not be afraid, to follow my heart, and they were always there to inspire me when I faltered. Their support, patience, and excellent humor brightened my journey. I am blessed, honored and humbled to have the loyalty, love, and support of my wife, daughters, and son.

Acknowledgments My incredible dissertation chair, Dr. Diane Neal, is deserving of my sincere appreciation and acknowledgement for her wisdom, great-natured support, advice, and encouragement through the dissertation writing process. The professionalism, dedication, and wealth of knowledge of the Walden faculty and staff are greatly appreciated. I would like to specifically acknowledge Dr. Gudeta Fufaa for his review and advice. My committee

member Dr. Aimee Ferraro has generously given her time and expertise to improve the quality of my dissertation. I thank her for her strong reasoned voice during the dissertation writing process. My URR, Dr. Scott McDoniel, is an excellent URR and I thank him for his contribution and support. I look forward to our paths crossing professionally in the future. I would also like to acknowledge the staff at the Walden Writing Center, with special acknowledgement to Timothy McIndoo. I must acknowledge as well the infection control nurse, the department of pathology staff, the department of preventive medicine staff, and the command staff at this army community hospital, and the IRB staff at the military academy who assisted, advised, and supported my research.

Table of Contents List of Tables .......................................................................................................................v List of Figures .................................................................................................................... vi Chapter 1: Introduction to the Study....................................................................................1 Background ....................................................................................................................2 S. aureus Epidemiology .......................................................................................... 2 Pathogenesis of a S. aureus Infection ..................................................................... 3 Emergence of CA-MRSA Infections in the United States...................................... 5 Molecular Classification of MRSA Strains ............................................................ 5 S. aureus Virulence Factors .................................................................................... 6 Risk Factors for S. aureus ....................................................................................... 7 Cadet Life at the Academy ..................................................................................... 7 Problem Statement .........................................................................................................9 Purpose of the Study ....................................................................................................10 Research Questions and Hypotheses ...........................................................................10 Research Question 1 ............................................................................................. 10 Research Question 2 ............................................................................................. 11 Research Question 3 ............................................................................................. 12 Conceptual Framework ................................................................................................13 Nature of the Study ......................................................................................................14 Key Variables...............................................................................................................15 Dependent and Independent Variables and Confounders ..................................... 15 i

Definitions....................................................................................................................16 Assumptions, Limitations, Scope and Delimitations ...................................................16 Assumptions .......................................................................................................... 16 Scope and Delimitations ....................................................................................... 17 Limitations ............................................................................................................ 18 Significance of the Study .............................................................................................18 Summary ......................................................................................................................20 Chapter 2: Literature Review .............................................................................................22 Literature Search Strategy............................................................................................22 Epidemiologic Triangle and Epidemiologic Theory....................................................23 Etiologic Agent ..................................................................................................... 23 Method of Transmission ....................................................................................... 24 Host

................................................................................................................... 24

Environment .......................................................................................................... 24 CA-MRSA Prevalence .................................................................................................25 S. aureus in Hospital Settings ......................................................................................27 S. aureus Infection in Vulnerable Populations ............................................................29 MRSA Infection in the Veterans Affairs Hospitals .............................................. 30 MRSA Infection in Athletic Training Settings ..................................................... 31 MRSA Infection Among High School Football Players....................................... 31 CA-MRSA Infections in Children ........................................................................ 33 CA-MRSA Infections in the Military Community ............................................... 34 ii

CA-MRSA Characteristics...........................................................................................38 Review of Methodology from Risk Factor Studies .....................................................39 Summary and Conclusion ............................................................................................42 Chapter 3: Research Method ..............................................................................................44 Research Objective ......................................................................................................44 Research Design...........................................................................................................44 Study Population ..........................................................................................................45 General Eligibility Criteria ..........................................................................................46 Research Question 1 ....................................................................................................47 Cases Needed for Research Question 1 ................................................................ 49 Definition of Variables ......................................................................................... 50 Assumptions of Poisson Regression ..................................................................... 50 Research Question 2 ....................................................................................................52 Research Question 3 ....................................................................................................53 Definition of Variables ......................................................................................... 54 Participant Protection ...................................................................................................54 Summary ......................................................................................................................55 Chapter 4: Results ..............................................................................................................56 Description of the Sample ............................................................................................56 Descriptive Statistics ............................................................................................. 56 Chi-square Test ..................................................................................................... 57 Molecular Typing.................................................................................................. 58 iii

Analysis of PFGE ................................................................................................. 59 Summary of Descriptive Statistics ...............................................................................60 Results ..........................................................................................................................60 Research Question 1 ............................................................................................. 60 Research Question 2 ............................................................................................. 66 Research Question 3 ............................................................................................. 70 Summary and Transition ..............................................................................................73 Chapter 5: Discussion ........................................................................................................75 Research Question 1 ....................................................................................................75 Identification of Independent Variable ................................................................. 76 Interpretation of Findings ..................................................................................... 77 Research Question 2 ....................................................................................................79 Interpretation of Findings ..................................................................................... 79 Research Question 3 ....................................................................................................81 Interpretation of Independent Variables ............................................................... 81 Interpretation of Findings ..................................................................................... 82 Implications for Social Change and Recommendations for Prevention ......................83 Limitations of the Study...............................................................................................84 Conclusion and Recommendations for Further Study .................................................85 References ..........................................................................................................................89 Curriculum Vitae .............................................................................................................101

iv

List of Tables Table 1. Study Dependent and Independent Variables, and Confounders ....................... 15 Table 2. Variables and Definitions of Each Variable Collected for the Study Cases ....... 50 Table 3. Variables and Definitions of Each Variable Collected for the Study Cases ....... 54 Table 4. Characteristics of Research Question 1 Cases (N = 162) ................................... 57 Table 5. Chi-square Test to Evaluate the Association Between Gender and the Infection (N = 162) ................................................................................................................... 58 Table 6. Molecular Typing Results(N = 7) ....................................................................... 60 Table 7. Model Goodness of Fit ....................................................................................... 65 Table 8. Model Parameter Estimates ................................................................................ 66 Table 9. MRSA Colonization of Environmental Specimens by Plate Type (N = 13) ...... 68 Table 10. Fisher’s Exact Test for Colonization Rate Within Barracks (N = 9) ................ 70 Table 11. Fisher’s Exact Test for Colonization Rate Within the Cadet Fitness Center (N = 13) ............................................................................................................................. 70 Table 12. Breakdown of CA-MRSA Cases by Month and Training Year (N = 162) ...... 71 Table 13. Effect of Seasonality on the Variability of CA-MRSA Infection (N = 162) .... 73

v

List of Figures Figure 1. Theoretical framework of CA-MRSA infection at the military academy ..........14 Figure 2. Study design for Question 1 ...............................................................................48 Figure 3. Power calculations for a cohort study ................................................................49 Figure 4. Covariates for Question 1 ...................................................................................51 Figure 5. Approach for Research Question 2.....................................................................53 Figure 6. Pulsed-field electrophoresis of isolates ..............................................................59 Figure 7. Comparison of CA-MRSA infection rates .........................................................62 Figure 8. Plot of deviance residual against predicted value of mean of response .............64 Figure 9. Cases of CA-MRSA by weather seasons ...........................................................72

vi

1 Chapter 1: Introduction to the Study Staphylococcus aureus (S. aureus) is a gram-positive cocci bacterium that resides in the nose of approximately 30% of people (Moellering, Abott, & Ferraro, 2011). While S. aureus is a harmless normal flora bacterium, some of its strains, such as methicillinresistant S. aureus (MRSA) 300 and MRSA 400 cause severe skin and soft-tissue infections. The Centers for Disease Control and Prevention (CDC; 2011) stated that infections caused by S. aureus, such as bacteremia, pneumonia, endocarditis, and osteomyelitis, can cause significant morbidity or mortality in health care settings. The pathogenesis of a S. aureus infection occurs in two phases. Kreisel (2009) indicated that during Phase-1 of the infection, a noninfected person acquires a S. aureus bacterium through exposure. The transmission can be direct, that is, through person-toperson contact, such as via airborne routes or skin-to-skin contact. In Phase-2, the exposed person develops an infection due to the bacterium’s invasion of the blood stream. The invasion takes place through a break in the skin or mucosal lining. I used a retrospective cohort study design to evaluate and compare communityacquired MRSA (CA-MRSA) infection rates between fourth class cadets and other classes of cadets at a particular U.S. military academy. I also surveyed the military academy environment to ascertain potential sources of bacteria responsible for the infection and investigated any seasonal effects associated with infection rates. Deidentified historical data collected by an infection control nurse at an army community hospital from April, 2005 through July, 2012 for a performance improvement program was used to evaluate MRSA cases.

2 Background S. aureus Epidemiology S. aureus is a gram-positive cocci bacterium that normally colonizes the nose and skin of healthy people (Von Eif, Becker, Machka, Stammer, & Peters, 2001). This is an opportunistic bacterium because it causes skin infections, resembling spider bites, when the skin is compromised. The bacterium invades a skin wound to cause an infection that primarily looks like a minor pimple or boil. Occasionally, severe skin infections develop when the bacterium enters the blood stream. Some S. aureus strains are resistant to certain antibiotics. These strains cause both CA-MRSA and hospital-acquired or health care–associated MRSA (HA-MRSA) infections. Klevens et al. (2005) indicated that approximately 94,360 invasive MRSA cases in the United States were related to 18,650 deaths annually. Sir Alexander Fleming first discovered penicillin in 1928 (Estes, 2011). In the 1940s, penicillin was effectively used to cure a large array of infectious diseases including S. aureus. However; in the late 1950s, penicillin was found to be ineffective in the treatment of S. aureus. Estes (2011) indicated that the discovery of methicillin in 1959 allowed for the successful treatment of penicillin-resistant S. aureus infections until cases of MRSA were observed in United Kingdom and Australia in 1961 and in the 1970s, respectively. Subsequently, similar observations were reported throughout the world. Annually, in the United States, more than half of skin infections are categorized as MRSA infections with spider or insect bite appearance. Symptoms in these cases include red, swollen, painful, and warm skin lesions.

3 The majority of nosocomial bloodstream infections, operative wound infections, and nosocomial pneumonia in the United States over the past 20 years was caused by S. aureus strains, of which 5% were resistant to penicillin in 1997 (CDC, 1997). The first case of S. aureus penicillin resistance was reported in early 1942. Subsequently, betalactamase, an enzyme which hydrolyzes the S. aureus lactam ring, was discovered to mediate penicillin resistance (CDC, 1997). MRSA infections emerged in the 1980s predominantly in the health care settings. MRSA isolates were found to be sensitive only to the antibiotic vancomycin in 1987. The use of vancomycin to treat HA-MRSA increased by 33.4% from 1987 [22.8%] to 1997 [56.2%] (CDC, 1997). However, Suryadevara, Moro, Rosenbaum, Kiska, Riddell, & Weiner (2010) indicated that vancomycin resistance cases have been observed as CA-MRSA infections on the rise with significant geographic variations. Reyes et al. (2009) indicated that the USA300 strain of CA- MRSA was responsible for the increased rate of infections across Latin America. While CA-MRSA blood stream infections have beennoted less in the United Kingdom than in the United States, the rate of staphylococcal skin and soft-tissue infections (SSTIs) and other complicated infections has significantly increased over the past decade among children in the United Kingdom (Otter & French, 2010). Other CA-MRSA variants have been seen in Europe, Asia, and Australia (Reyes et al., 2009). Pathogenesis of a S. aureus Infection S. aureus is a normal bacterial flora of humans; however, it is a pathogen that can cause life-threatening infections to compromised human tissues (Roghmann & McGrail,

4 2006). This pathogen adapts well to humans, evades immune systems, and causes severe infections in two phases: the exposure to and invasion of the bacterium (Phase-1), and the infection development (Phase-2; Roghmann & McGrail, 2006). In Phase-1, a person carrying S. aureus as a normal bacterial flora becomes injured with disrupted or bruised skin. The wounded skin is exposed to the bacterium and colonized by it (Roghmann & McGrail, 2006). The transmission of the bacterium can occur directly person-to-person through skin-to-skin contact or shared air. Colonization by the bacterium can also occur indirectly via risk factors such as exposure to contaminated soap, razors, towels, clothing, fitness center equipment, and bathrooms (Roghmann & McGrail, 2006; Kreisel, 2009). In Phase-2, the bacterium penetrates the bruised skin or mucosal lining and invades or eludes the host’s defense mechanism to cause infection in various tissues (Roghmann & McGrail, 2006). In light of the fact that S. aureus is an opportunistic bacterium, infection does not occur in all colonized people. Knowledge of the transmission of this opportunistic pathogen is significant in formulating and implementing preventive measures (Roghmann & McGrail, 2006; Kreisel, 2009). S. aureus isolates are responsible for a wide spectrum of infections, which are classified as noninvasive and invasive (Diep, Sensabaugh, Somboona, Carleton, & Perdreau-Remington, 2004). SSTIs are the most common noninvasive infections caused by S. aureus isolates. Murray, Rosenthal, Kobayashi, & Pfaller (1998) indicated that cellulitis, abscesses, folliculitis, furuncles or curbuncles, and impetigo are most common clinical manifestations of SSTIs. The study performed by Frazee, Lynn, Charlebois,

5 Lambert, Lowery, & Perdreau-Remington in 2005 revealed that a strain of S. aureus was the cause of approximately 50% of all emergency department SSTIs. In the case of an invasive infection, S. aureus strains penetrate and infect sterile body sites. According to Klevens et al. (2007), sterile body sites include blood, cerebrospinal fluid, pleural fluid, synovial fluid, pericardial and peritoneal fluids, bone, and internal body sites such as lymph node, brain, heart, spleen, liver, kidney, pancreas, ovary, and vitreous fluid. Infections caused by S. aureus isolates include septic arthritis, pneumonia, and osteomyelitis. Strains responsible for causing necrotizing pneumonia are extremely fatal (Klevens et al., 2007). Emergence of CA-MRSA Infections in the United States In 1999, the first outbreaks of CA-MRSA were observed among children of rural Native Americans (Moellering et al., 2011). Subsequently, outbreaks were reported among prison inmates, contact sport players, and homosexual men. In 2005, some United States cities revealed that 63 to 76% of all reported strains of community-acquired S. aureus (CA-SA) were methicillin-resistant. As a result; every American is at risk for the spread of CA-MRSA infections, and the distinction between HA-MRSA and CA-MRSA often becomes ambiguous. Of all the CA-MRSA clones in the United States, US300 is responsible for 90 to 95% of the outpatient isolates (Moellering et al., 2011). Molecular Classification of MRSA Strains Webber (2005) stated that CA-MRSA infections have major similarities to and differences from HA-MRSA infections. Genetically, significant numbers of CA-MRSA isolates carry the Panton-Valentine leukocidin (PVL) virulence factor and contain

6 staphylococcal cassette chromosome (SCC) mec type IV or V (Huijsdens et al. 2006); a combination of the mec gene complex and the ccr gene complex responsible for encoding methicillin resistance and motility recombinases, respectively (Ito, Ma, Takeuchi, Okuma, Yuzawa, & Hiramatsu, 2004). In light of this, Naimi et al. (2003) indicated that the majority of CA-MRSA strain was not associated with health care settings and their microbiological characteristics led to their occurrence in the community. USA300 and USA400 clones are the major strains of CA-MRSA. Genetically, they are composed of SCCmec IV, smaller in size and responsible for resistance, in contrast to the SCCmec I, II, III, and V, found in both HA-MRSA strain US 100 and US 200 (Moellering et al., 2011). The smaller the SCC, the less resistance there is. This explains why HA-MRSA is resistant to more categories of antibiotics than CA-MRSA, which is often resistant to erythromycin and always to beta-lactams. HA-MRSA is only susceptible to vancomycin, daptomycin, linezolid, tigecyline, and quinoprisitindalfopristin. Nearly all CA-MRSA clones contain the PVL gene that facilitates the production of a necrotizing cytotoxin, responsible for the colonization and virulence of the organism. However, only 5% of methicillin-susceptible S. aureus strains and HAMRSA possess the PVL gene (Moellering et al., 2011). S. aureus Virulence Factors The bacterium cell wall, enzymes, and polypeptide toxins constitute the virulence factors of S. aureus (Moellering et al., 2011). The cell wall components facilitate the adhesion and penetration of host cells. The bacterium enzymes play a major role in tissue colonization. Then, the bacterium polypeptide toxins damage human cell membranes and

7 serve as superantigens. The combination of enterotoxins and exfoliatin exotoxins can prompt the activation of lymphocytes, resulting in the release of cytokines that triggers fever, skin lesions, multi-organ failure, hypotension, shock, and death. Multiple regulatory systems, to include the accessory gene regulator (AGR), control the release of the bacterium virulence factors (Moellering et al., 2011). Risk Factors for S. aureus Estes (2011) indicated that MRSA skin infections in the past occurred almost entirely in health care settings (HA-MRSA) where risk factors were recent hospital admission, surgery, prior antibiotic exposure, invasive hospital devices, and exposure to a patient infected with MRSA. In the late 1990s, MRSA infections emerged in the community with almost entirely different risk factors. The CDC indicated in May 2010 that such MRSA infections often occur in detention centers, athletic training facilities, close-contact sports, military basic training centers, and among drug users and homosexual men. CA-MRSA risk factors include skin-to-skin contact, sharing of equipment or clothing, skin damage, increased prevalence rate of CA-MRSA in the local community, poor hygiene, nasal MRSA carriage, history of MRSA, frequent use of antibiotics, shaving of pubic hair, children 2 years old or younger, or affiliate of Native American, Pacific Island, and Alaska (Borlaug, Davis, & Fox, 2005; CDC, 2010). Cadet Life at the Academy The areas of concentration for this research were to: (a) compare the infection rate between fourth class cadets and other classes of cadets, (b) ascertain sources of bacteria responsible for the infection, and (c) evaluate the seasonal effect in the rate of S. aureus

8 infections at the academy, which recruited approximately 1300 new cadets and graduated about 900 cadets annually. Cadet life at the academy starts at R-Day, or Reception Day, in July when cadets are registered in the academy to fulfill the 4-year long cadet training program. During their first year, new cadets live in the barracks for 6 weeks before integrating into respective regiment or company halls, have limited privileges to eat in the mess hall, and attend cadet summer initial training to include field training during the summer before their first semester of classes. During R-Day, new cadets are briefed in the morning, have 90 seconds to say goodbye to their friends and family members, and go through 6 hours of processing and training to include having a physical, getting haircuts, and receiving uniforms. New cadets take their oath to complete R-Day and begin 6 weeks of intensive initial training. In general, cadets consider initial training to be a culture change at the academy due to the strenuous transition from civilian to military life. In the second year, third class cadets live in the residence halls, eat in the mess hall, attend academic classes, participate in sports, and concentrate on cadet leadership development to include field training in the summer. In the third year, second class cadets live in the residence halls, eat in the mess hall, attend academic classes, participate in sports, and focus on leadership training in the summer. In the fourth year, first class cadets live in the residence halls, eat in the mess hall, attend academic classes, participate in sports, and concentrate on command role training in the summer. In light of the cadets’ activities, cadets enrolled in the first and second year of the academy were more likely to be exposed to CA-MRSA risk factors due to the nature of the cadet basic training, field training program, and the utilization of the cadet fitness center. Poor personal hygiene

9 and skin abrasion could play a significant role in the colonization of skin by a CA-MRSA strain. Cadets enrolled in the third and fourth year could be exposed to CA-MRSA risk factors due to their participation in sports and the utilization of the cadet fitness center. Problem Statement Incidence associated with MRSA in the community has been increasing since 1990 (Cohen & Kurzrock, 2004) as the prevalence of CA-MRSA has surged among cultured skin-infection isolates (Groom et al., 2001). In the United States, CA-MRSA strains USA300 and USA400 have been responsible for most skin and soft tissue infections seen in emergency rooms (Klevens et al., 2007; Moran et al., 2005). Although most studies focused on CA-MRSA infection in high school, college, wrestling, rugby, fencing, and professional football teams, other vulnerable populations include military recruits, children in day care, homosexual men, and prison inmates (Martinez, 2011). While the incidence rate of CA-MRSA infection is on the rise in the community, the prevalence of CA-MRSA is still misunderstood due to skin infection isolates not being routinely cultured (Groom et al., 2001). CA-MRSA colonization occurs directly or indirectly via risk factors such as exposure to contaminated soap, razors, towels, clothing, fitness center equipment, and bathrooms (Roghmann & McGrail, 2006; Kreisel, 2009). Even though CA-MRSA has become a serious concern in the health care profession, it is unclear whether military installations also serving as college campuses, such as the military academy that served as the site for this study, foster an environment where CAMRSA can be easily spread among the population.

10 The following risk factors were associated with CA-MRSA infections in the military community: (a) poor hygiene, (b) contaminated fitness center equipment, (c) basic training, and (d) confined barracks (Zinderman et al., 2003). The risk of infection associated with exposure to these risk factors increased among fourth class cadets. There were also a seasonal component to incidence. Purpose of the Study The primary goal of this quantitative study was to investigate confirmed MRSA cases among cadets at a particular army military academy, with an emphasis on the identification of the MRSA strains responsible for the infections. Particular focus of the study was to: (a) identify CA-MRSA cases among cadets and compare incidence rates between fourth class cadets and other classes of cadets, (b) collect and test environmental bactrial isolates for MRSA within the military academy common areas to identify sources of infection, (c) illustrate and compare seasonal trends of CA-MRSA infections among cadets. The identification of risk factors for CA-MRSA skin and soft-tissue infections among cadets at the academy may constitute the basis for formulating effective preventive measures to reduce the incidence rate of the infection. Research Questions and Hypotheses Research Question 1 Is there a difference in CA-MRSA incidence rates between fourth class cadets and other classes of cadets after controlling for potential confounders? H01: There is no significant difference in CA-MRSA incidence based on cadet status as fourth class cadets or other classes of cadets.

11 Ha1: There is a significant difference in CA-MRSA incidence based on cadet status as fourth class cadets or other classes of cadets. The transmission of CA-MRSA mostly occurs through an open wound, such as a skin abrasion, or from skin-to-skin contact with a CA-MRSA colonized person. Additional routes of transmission consist of poor personal hygiene, sharing of personal equipment or clothing, poor hand washing, increased prevalence rate of CA-MRSA in the local community, or contaminated physical fitness equipment (Borlaug et al., 2005; CDC, 2010; Martinez, 2011). Fourth class cadets, who are exposed to initial basic training activities at the military academy, are also prone to wear dirty uniforms and experience poor personal hygiene. In 2003, Zinderman et al. investigated MRSA infections among recruits in military facilities in the southeastern United States. The authors indicated a significant increase of MRSA cases among recruits during the first 5 weeks of basic training. Research Question 2 Are barracks where fourth class cadets live or the cadet fitness center at the military academy potential sources of bacteria responsible for CA-MRSA infections among cadets? H02: Barracks where fourth class cadets live or the cadet fitness center at the military academy are not potential sources of bacteria responsible for CA-MRSA infections among cadets.

12 Ha2: Barracks where fourth class cadets live or the cadet fitness center at the military academy are potential sources of bacteria responsible for CA-MRSA infections among cadets. MRSA outbreaks have occurred in the community settings to include military basic training facilities, correctional facilities, and athletic team facilities (CDC, 2010). The bacteria responsible for MRSA infections may spread easily among people with poor hygiene practices who live in crowded and unsanitary conditions (New York State Department of Health, 2007). Contaminated physical fitness equipment were also identified as sources of bacteria responsible for CA-MRSA infection (Borlaug et al., 2005; CDC, 2010; Martinez, 2011). During summer initial training, fourth class cadets live in open and dirty barracks and use the cadets’ fitness center. Research Question 3 Is an increased incidence of CA-MRSA infection among cadets associated with changes in weather season at this particular military academy? H03: An increased incidence of CA-MRSA infection among cadets is not associated with changes in weather season at the military academy. Ha3: An increased incidence of CA-MRSA infection among cadets is associated with changes in weather season at the military academy. CA-MRSA USA300 clone has greater pathogenic potential due to its PVL gene, which triggers the production of a necrotizing cytotoxin, colonization, and virulence factors. Hamill (2012) indicated that crowds, sweat, and hot and humid weather foster an environment where S. aureus breeds. While CA-MRSA infections are not easily

13 prevented, basic training activities held during the summer season could be a source of increased cases of MRSA infections among fourth class cadets. Conceptual Framework The framework for this analytical study was the epidemiology theory and the epidemiologic triangle. Brachman (1996) indicated that the chain of infection, which is comprised of the etiologic agent, the method of transmission, and the host, is the basis for epidemiological approaches. According to Williams and Nelson (2001), the epidemiologic triangle—the association between the host, the agent, and the environment—is a useful conceptual framework in mapping the spread of an infectious disease. The theoretical framework is described at length in Chapter 2; however, the association between the host, the agent, and the environment of MRSA infections at the military academy is depicted in Figure 1.

14

AGENT: CA-MRSA

HOST: Fourth class cadets and other classes of cadets, as well as demographic factors

ENVIRONMENT: Military academy training area, common areas, and hot weather.

Figure 1: Theoretical framework of CA-MRSA infection at the military academy.

Nature of the Study This retrospective cohort study was designed to (a) ascertain CA-MRSA cases and compare incidence rates between fourth class cadets and other classes of cadets, (b) collect and test environmental culture specimens for CA-MRSA strain within the military academy common areas, barracks where fourth class cadets lived, and the fitness center to identify sources of infection, and (c) illustrate and compare seasonal trends of CAMRSA infections among cadets. Independent variables, fourth class cadets and other classes of cadets, laboratory results, and cadets’ demographics were reviewed and charted by an infection control nurse at the army community hospital. The study cohort was male and female cadets who attended the military academy between April 2005 and July 2012.

15 The inclusion and exclusion criteria are further defined in Chapter 3. Statistical analysis was performed using IBM SPSS Statistics 20 statistical software. Secondary data and collected environmental data were organized into tables and graphically represented for descriptive analyses. I also performed a comparison analysis of differences in rates of infection per person-time years based on cadets’ status at the military academy using Poisson regression. Key Variables Dependent and Independent Variables and Confounders The dependent, independent, and confounder variables are depicted in Table 1 with respect to Research Questions 1 and 3. Definitions for the dependent and independent variables and confounders are described in Chapter 3. Table 1 Study Dependent and Independent Variables, and Confounders Research question number

Dependent variable

1

CA-MRSA infection rate

3

CA-MRSA infection rate

Independent variable Confounders Fourth class cadets Gender and other classes of Race/ethnicity cadets

Seasons: winter spring summer fall

16 Definitions CA-MRSA: Confirmed cases of MRSA infections by microbiology screen testing and molecular typing of isolates for strain identification. According to CDC (2005), CAMRSA is diagnosed in hospital settings within 48 hours of admission using culture swabs Carrier. A host for a pathogen that gets to transmit it to others asymptomatically (Carrier, 2012). Colonization. The process in which microorganisms invade a host without causing infection (Colonization, 2012). Infection. Process in which pathogenic microorganisms invade and multiply in a host tissue (Infection, 2012). Isolate. Bacterial culture sample to be molecular typed for a specific strain (Isolate, 2012). Reservoir. A source in which an infectious agent normally lives and multiplies (Reservoir, 2012). Virulence. Extremely infectious or capable of causing disease by weakening the host immune system (Virulence, 2012). Assumptions, Limitations, Scope and Delimitations Assumptions A major assumption of this study was that 99% of all historical cases were CAMRSA cases since no molecular testing was performed to determine the strain responsible for causing skin and soft-tissue infection among cadets. All historical cases tested positive for MRSA at the army community hospital laboratory. Retrospectively, I

17 established the baseline exposure in accordance with the above assumption and the laboratory-confirmed MRSA isolates. Additionally, I assumed that potential risk factors, exposure to contaminated fitness center equipment, laundry rooms, lockers, and exposure to cadet initial basic training or field training activities, were associated with historical MRSA cases. I collected and tested environmental bacterial isolates for CA-MRSA strain to reject or support the latter assumption. Scope and Delimitations This retrospective study was designed to: (a) evaluate whether there was a difference in CA-MRSA incidence rates between fourth class cadets and other classes of cadets, (b) ascertain whether barracks where new cadets lived during initial basic training or the fitness center at the military academy were potential sources of bacteria responsible for CA-MRSA infections, and (c) observe and describe the seasonal effect in the variability of CA-MRSA incidence rates. Even though the scope of this study was limited to the military academy, the findings are relevant to other military institutions. While the outcome of this study may trigger positive social changes to include increased CA-MRSA awareness, a number of interesting research questions, such as what aspect of military basic training activities at the military academy were risk factors for CA-MRSA infection among fourth class cadets or whether poor hygiene was a risk factor for CAMRSA infection among fourth class cadets, could have been asked and pursued. These questions were not pursued in this study because (a) the focus of the inquiries was on comparing the disease incidence rates between fourth class cadets and other classes of cadets with respect to their environment and the weather, not on the aspect of basic

18 training activities, and (b) the inclusion of these questions, while appealing, would have been beyond the scope of this study. For this research, all historical cases were laboratory-confirmed MRSA cases. Cadets with skin infection caused by non-MRSA strains were disqualified from the study. Limitations This study had several limitations. I obtained the de-identified secondary data from an infection control nurse at the army community hospital. These secondary data were associated with laboratory-confirmed MRSA cases. Since the secondary data contained limited variables such as age, gender, infection rate, and cadets’ status, I was compelled to compare infection rates rather than conduct a true case-control. The requirements for a true case control study include the implementation of a questionnaire to collect information on both non-cases and cases pertaining to living quarters, personal hygiene, the frequency of the fitness center usage, and the exposure to basic or field training activities. This data was not available for this study. Secondly, I was limited to survey only a fitness center and the two barracks where new cadets lived during initial basic training at the military academy in an effort to determine common areas where CAMRSA strains could be found. Significance of the Study This study was the first to evaluate and compare the incidence rate of CA-MRSA infection among cadets at the military academy. To reduce the prevalence rate of the infection, it is imperative to establish the potential sources of infection and to determine risk factors for the disease. I collected culture specimens from potential sources of

19 infection, barracks, fitness center equipment, and lockers for MRSA testing and molecular typing in an effort to fill a gap in the literature. While MRSA cases have been monitored seasonally by an infection control nurse at the army community hospital, molecular testing of laboratory-confirmed MRSA isolates, the testing of environmental culture specimens, and the comparison of the disease incidence rate between fourth class cadets and other classes cadets had not been performed prior to this study. With the molecular testing of MRSA isolates, I first associated MRSA infections among cadets with a specific strain of CA-MRSA and subsequently compared the incidence rate of the disease between fourth class cadets and other classes of cadets. This may allow the army military academy to formulate interventions to reduce MRSA transmission. Secondly, I surveyed the army military academy environment and collected and tested culture specimens to identify sources of bacteria responsible for the infections. This particular military academy may use the outcome of this environmental survey to review and amend the institution cleaning and sanitation policies. Thirdly, I evaluated the implication of weather change at the military academy in the occurrence of CA-MRSA infection among cadets. This approach may enable the academy to develop an effective MRSA educational program and MRSA preventive measures. Benefits of reducing MRSA transmission are not limited to cadets, as the military academy community also includes army active duty soldiers and their family members, who are also at risk for the disease. These individuals may also benefit from this research and its conclusions. Ultimately, the outcome of this study could trigger a positive social change in guiding activities, such as policies to implement effective preventive measures, at both military training installations

20 and university campuses in how to avoid this costly infection. The evaluation of CAMRSA incidence rate and sources of bacteria responsible for the infections at the military academy was of particular importance, as little has been discovered about risk factors for the spread of the infection in community settings (Borlaug et al., 2005). Summary S. aureus is a gram-positive cocci bacterium that lives in the nose of about 30% of people (Moellering et al., 2011). S. aureus adapts well to humans, colonizes immune systems, and causes severe infections in two phases: the exposure to and colonization of the bacterium (Phase-1), and the infection development (Phase-2; Roghmann & McGrail, 2006). This research was designed to: (a) evaluate whether there was a difference in CAMRSA incidence rates between fourth class cadets and other classes of cadets, (b) ascertain whether barracks where fourth class cadets lived during initial basic training or a fitness center at the military academy were potential sources of bacteria responsible for CA-MRSA infections, and (c) observe and describe the seasonal effect in the variability of CA-MRSA incidence rates. The outcome of this research could generate a positive social change in guiding activities, such as amendments in policies to implement effective preventive measures, at both military training installations and university campuses in how to avoid this costly infection. In Chapter 2, I present a review of pertinent studies about S. aureus infection in vulnerable population. This literature review guided the design and focus of the proposed research. I also review relevant studies on potential CA-MRSA risk factors and methodology. In addition, I describe the retrospective cohort study design, data collection

21 and analysis, the study population, the study sample size, the inclusion and exclusion criteria, the participant protection, the laboratory testing algorithm, and the definition of variables. In Chapter 3, I introduce the research design and methodology, population, study cases, and procedures for attaining approval for use of the data. I also discuss the three research questions and the methods I used to answer them. In addition, I describe the acquisition of secondary data, collection and analysis of environmental data, laboratory testing, and protection of participant privacy and confidentiality. In Chapter 4, I present the results related to the three research questions. I descibe both the secondary data and the results of the samples I collected. In Chapter 5, I interpret the results of this research in relation to the conceptual framework. I also describe the study’s limitations, present recommendations for further study in accordance with the study’s findings and current literature, discuss the implications for positive social change related to public health concerns, and summarize the key outcomes of this study.

22 Chapter 2: Literature Review The objective of this study was to acquire a better understanding of the risk of CA-MRSA infection at a particular U.S. military academy by looking at factors related to the host (cadets), environment (weather) and potential fomites, and barracks or contaminated fitness center equipment. The molecular typing of MRSA isolates coupled with the identification of the sources of infection is paramount to formulate and implement effective preventive measures. The conceptual framework of this study, the epidemiologic triangle and the epidemiology theory, was crucial in establishing a relationship between the host, the agent, and the environment. In the first section of this chapter, I identify the research literature search and pertinent search terms. In the second section, I elaborate on the epidemiologic triangle and the epidemiology theory in order to explicate the proposed research. In the third section, I review relevant literature related to the proposed study and expose an existing gap. In the fourth section, I present an overview of the research proposed methodology. Literature Search Strategy The databases used in this literature search included Google Scholar, CINAHL, Academic Search Premier, Medline, CDC.gov, ProQuest, PubMed, USAPHC (US Army Public Health Command), and NEJM (New England Journal of Medicine). Search terms consisted of epidemiology of S. aureus, MRSA, CA-MRSA, HA-MRSA, and each risk factor was searched independently. The research literature review was limited to studies conducted in the United States since 2006. A few earlier studies were included for clarity. One study conducted outside the United States was included due to its particular

23 relevance. The focus of the majority of studies has been on S. aureus infections in the health care settings. Despite the increase in incidence rate of non-outbreak CA-SA and CA-MRSA in the community, only a few studies were conducted to identify risk factors for CA-MRSA and CA-SA in the general population. Epidemiologic Triangle and Epidemiologic Theory This study’s theoretical framework was crucial in the understanding of the links in the chain of infection (Brachman, 1996). Russell (2010) used the epidemiologic triangle to establish the relationship between the agent, environment, and the host in the determination of the existence of MRSA on the diaphragm of clinicians’ stethoscopes. In this section, each factor in the chain of infection, a replication of an agent in the host’s tissue, are described in depth. It was important to have a clear understanding of these factors—etiologic agent, method of transmission, host, and environment—prior to the formulation and implementation of any preventive measures. Etiologic Agent An infection is caused by a microorganism known as an etiologic agent. The agent’s ability to cause disease is characterized by its pathogenicity: the microorganism’s invasiveness and virulence (Brachman, 1996). The invasiveness of a microorganism resides in its genetic make-up responsible for invading tissue. The virulence of a microorgamism is directly proportional to the severity of an infection, related morbidity, and mortality rate (Brachman, 1996). The etiologic agent in this research was CAMRSA; its virulence and genetic make-up was described in depth in Chapter 1.

24 Method of Transmission The method of transmission is the way in which the microorganism travels from the infected source to the susceptible host. Key methods of transmission include contact; direct, indirect, or airborne droplets; common vehicle; fomites, drugs, food, or water; airborne transmission; droplet nuclei or dust; and vector borne transmission involving arthropods (Brachman, 1996). In this research, contact transmission was the means by which CA-MRSA travelled from the source to the host. Host The host is the site where an infectious agent enters to reside, metabolize, and multiply. The microorganism could invade the host through the skin, respiratory system, mucus membranes, genito-urinary tract, digestive system, and the placenta. The severity of the infection in the host reflects the virulence of the microorganism in relation to the host immune system response, which could be nonspecific or specific. While nonspecific immune systems consist of the skin, mucous membranes, enzymes, excretions, secretions, genetic factors, the inflammatory response, hormones, nutrition, behavioral patterns, and the occurrence of other diseases, specific immune systems take place naturally, from exposure to a microorganism, or artificially, from active or passive immunization (Brachman, 1996). The targeted hosts for this current research were male and female cadets who attended the military academy between April 2005 and July 2012. Environment The environment interacts with the infectious agent, the methods of transmission, and the host. The major environmental factors include the ambient temperature, which

25 facilitates or prevents multiplication of microorganisms at their reservoir; the air velocity, which helps the airborne motion of droplet nuclei; low humidity, which can affect mucous membranes; and ultraviolet radiation, which is capable of killing organisms. The evaluation of the causal relationship between disease incidence and environmental risk factors is crucial in the disease investigation process (Brachman, 1996; Williams & Nelson, 2007). This research was designed to examine the association between CAMRSA environmental risk factors and the susceptible hosts, in the transmission of the infection, among cadets at the military academy. CA-MRSA Prevalence In the 1960s, MRSA was the source of skin and soft-tissue infections among patients in health care settings (Moran et al., 2006). More recently, MRSA infections emerged among persons in the community. The prevalence of CA-MRSA was significant among prisoners, athletes, intravenous drug users, homosexuals, and military trainees (Moran et al., 2006). Forcade et al. (2011) conducted a study to assess the prevalence, severity, and treatment of CA-MRSA skin and soft-tissue infections. Ten medical clinics in Texas agreed to participate in the study. The prospective, community-based study design facilitated the collection of patients’ consent, socio-economic characteristics, diabetes history, and skin and soft-tissue infections history. Wound swabs were collected from patients for MRSA identification, susceptibility testing, and isolation. Patients selected for the study were 18 years of age or older, with skin and soft-tissue infections and a positive MRSA wound culture result. Data used in that study were associated with cases registered between October 1, 2009 and September 30, 2010 (Forcade et al., 2011).

26 Study results revealed that 73 of 119 selected cases had CA-MRSA infections; 49% were male, 71% were White, 7% were Black, 22% were “other”, and 30% were diagnosed with diabetes. In general, 49% of selected patients were female, 8% were Black, 72% were White, and 20% fell under the “other” category (Forcade et al., 2011). One of the weaknesses of this study was that molecular testing was not performed to support the assumption that all patients infected with MRSA had CA-MRSA. Unlike that study, I designed my research to retrospectively analyze historical cases in order to evaluate the prevalence rate of CA-MRSA among cadets at the military academy. Using my research case selection criteria, participants had to be 17 years of age or older with SSTI and a positive MRSA isolates. This was similar to the Forcade, et al. (2011) study. In addition, I was compelled to assume that all my research historical cases with no molecular testing were CA-MRSA cases as Forcade, et al. did in their study. MRSA isolates molecular typing is crucial in the study of community-associated outbreaks of MRSA infection. To fill this gap, David, Rudolph, Hennessy, Boyle-Vavra, & Daum (2008) conducted a study on molecular epidemiology of MRSA in rural southwestern Alaska to evaluate the association between the high prevalence of MRSA strains and both PVL toxin genes and SCCmec type IV elements in multiple predominant genotype backgrounds. David et al. used the historical prospective cohort study design to analyze historical data and evaluate 36 MRSA isolates from skin and soft-tissue infections outbreaks in 1996 and 2000. The outcome of the retrospective study revealed that all MRSA isolates were comprised of SCCmec type IV, of which, 92% contained PVL genes, 57% carried the sequence type (ST) 1 and 26% the sequence type ST30, 61%

27 were resistant to clindamycin, and none of them was associated with clonal complex (CC) 8, clonal complex of USA300. In the retrosprospective study, the authors collected data from 2004 through 2006 and examined 120 MRSA isolates. Overall, 42 isolates contained PVL+ and SCCmec type IV; 83.3% contained ST1, 9.5% contained ST30, and 7.1% contained ST8; and 57.5% were resistant to clindamycin. David et al. (2008) concluded that, in southwestern Alaska, the epidemiology of CA-MRSA diverged from the ones in the lower 48 states; clindamycin resistance was frequent and ST8 strains rarely caused skin infections in this region. For my study, I evaluated approximately 100 historical laboratory-confirmed MRSA cases, 10% of which were molecular typed to support the assumption that MRSA cases among cadets were caused by CA-MRSA strains. In addition, I collected select environmental culture specimens for molecular typing to establish potential sources of infection. S. aureus in Hospital Settings MRSA is known to be one of the major sources of health care-associated infections (Huskins et al., 2011). In light of this, Huskins et al. conducted a study to test their hypothesis that culture-based vigorous surveillance for MRSA coupled with the implementation of strict preventive measures, unlike current practice, would decrease the incidence rate of MRSA infection amongst adult ICU patients. Huskins et al.’s cluster randomized trial consisted of three phases: the baseline, the randomization and implementation, and the intervention. In Phase 1, all providers assigned to participating ICUs were educated about the use of the standard precaution. In Phase 2, an ICU was selected for the study if the unit was an adult surgical, medical, or medical–surgical ICU

28 with at least 1200 patient-days, and an estimated MRSA incidence rate of approximately nine cases per 1000 patient-days. In Phase 3, all intervention ICU staff were trained in the intervention process, door signs were posted eliciting each type of precaution, and providers were instructed through a memorandum to use and change gloves inbetween seeing different patients during the first month of the intervention stage. The intervention ICUs facilitated the collection of nasal swabs from the patients within two days of their admission each week afterwards, and within two days of their release, for MRSA subtyping and active surveillance. Even though my study was a retrospective study, not a cluster randomized trial, one similarity between the Huskins et al. study and mine was that MRSA isolates typing were performed to differentiate HA-MRSA from CA-MRSA. To contrast a clinical trial study design with a retrospective cohort study, I examined the study published by Bode et al. (2010). In this study, patients were randomly selected and screened by registered nurses for nostril colonies of S. aureus on admission or during the week preceding admission. The randomized, double-blind, placebocontrolled study was conducted to initiate decolonization therapy on admission. The study was conducted in the Netherlands at three university hospitals and two general hospitals from October 2005 through June 2007. Study participants were the departments of surgery and internal medicine in-patient, with high risk of S. aureus infection. This clinical trial had two goals, to estimate the incidence rate of HA-SA infections and to calculate the mortality rate at the hospitals in general, including the duration of hospital stay and length of time from admission to the onset of HA-SA infections.

29 Culture specimens were collected by attending physicians for microbiological testing and active surveillance of HA-MRSA. The CDC-established criteria were used to determine whether infections were hospital-acquired. Out of 6771 patients who were screened for the existence of S. aureus in the nostril, 1270 were positive for the bacteria by real-time polymerase chain reaction (PCR; Bode et al., 2010). The outcome of this study indicated that a swift detection of S. aureus colonies in the nostril coupled with an immediate treatment of the nostril and infected sites, with mupirocin nasal ointment and chlorhexidine gluconate soap, considerably decreased the risk of HA-SA infections in vulnerable patients. (Bode et al., 2010). The Bode et al. (2010) study differed from my retrospective research in few ways. First, my research was not a clinical trial. Second, Bode et al. (2010) conducted their study to evaluate MRSA treatment. I designed my research to evaluate MRSA incidence. However, culture isolates molecular testing for MRSA identification was the centerpiece of both studies. Even though Bode et al.’s study was conducted in the Netherlands and mine was conducted in the United States, incorporating all pertinent information to evaluate how all the environmental, epidemiological, and molecular information intertwined was the basic nature of a molecular epidemiological assessment. S. aureus Infection in Vulnerable Populations In the past, skin infections caused by MRSA were exclusively attributed to exposure to health care settings. Previous antibiotic exposure, recent hospital admission, surgical procedures, invasive health care instruments, and contact with a patient infected with MRSA are risk factors for HA-MRSA (Estes, 2011). In the late 1990s, MRSA

30 infections with no association with HA-MRSA risk factors were categorized as CAMRSA. This infection has been associated with lower socioeconomic status, exposure to jail, exposure to antibiotics, intravenous or intranasal drugs use, day care settings, military training, athletes, and the homeless population (Estes, 2011). MRSA Infection in the Veterans Affairs Hospitals Jain et al. (2011), the Pittsburgh Veterans Affairs (VA) Healthcare System, and CDC collaborated on a project, begun in 2007, designed to eradicate the transmission of HA-MRSA using an approach they termed the MRSA bundle. The bundle method encompassed a universal nasal surveillance for MRSA transmission, preventive measures for patients who have a history of MRSA infections, hand washing, and an organizational culture change where universal precaution is every health care professional’s responsibility. At the conclusion of implementation of the MRSA bundle in 2010, Jain, et al. conducted a cohort study of its effectiveness. The subjects recruited for the research were ICU and non-ICU patients aged 48 to 76 years old. Study subjects were mostly men and were drawn from the 153 VA hospitals nationwide. The outcome of that study revealed that the MRSA bundle approach was successfully implemented and the incidence rate for HA-MRSA at the VA hospitals was reduced by 60% on a surgical ward and 75% in an ICU ward. In light of the success of this pilot study, the Department of Veterans Affairs formulated a directive to implement the MRSA bundle approach in all 153 VA hospitals.

31 MRSA Infection in Athletic Training Settings A study was performed by Montgomery, Ryan, and Starkey (2010) to assess the prevalence of MRSA in a high school athletic training facility. Ten rural Southeast Ohio high schools agreed to participate in the study. Since no human testing was involved, a review and approval of the study protocol was not necessary. Surface culture samples of the basketball and wrestling training centers including locker rooms were obtained during the winter season. Surface specimen sampling was performed over two weeks. All culture samples were transported to the laboratory for MRSA testing and identification. Study results revealed the presence of MRSA in 9 of the 10 participating high schools. Out of 90 culture specimens obtained, 42 tested positive for MRSA. Water cooler surfaces, treatment tables, and locker rooms had the highest MRSA testing rate (Montgomery et al., 2010). The study outcome suggested that athletic training facilities were suitable locations for MRSA growth due to high traffic areas. Since this study was not designed to evaluate the effectiveness of cleaning procedures, Montgomery et al. (2010) indicated that the prevalence and preventive measures for MRSA should be the focus of future studies. In my research, I ascertained the prevalence and risk factors of CA-MRSA within a military setting. MRSA Infection Among High School Football Players The focus of most researches has been the investigation of CA-MRSA infection risk factors among the general population and athletes. However, none of these researches was designed to prospectively examine risk factors of CA-MRSA among

32 athletes throughout a given season (Lear, McCord, Peiffer, Watkins, Parikh, & Warrington, 2011). The study conducted by Lear et al. (2011) was to investigate cases of MRSA nasal colonization and SSTIs among high school football players. Also, both known and unknown MRSA infection risk factors were evaluated. Six high schools in northern Ohio agreed to participate in this study. 190 football players were selected, during the 2008 fall season, from varsity and junior varsity football teams for this prospective observational research. All participants, 14 to 18 years of age, signed a consent form with parents’ agreement, filled out a survey questionnaire, and were educated about CA-MRSA SSTIs risk factors before the football season started. Nasal swabs were collected from the survey population prior to the beginning of the football season. Study results showed no case of MRSA nasal colonization, 10 skin and soft tissue infections, and 44 incidence of MSSA nasal colonization. The review of survey questionnaires revealed no MRSA infection over the past year, 11% MSSA infections, 21% skin infections, and three cases of prior exposure to MRSA (Lear et al., 2011). The authors mentioned that skin and soft tissue infection, 5.3% incidence rate, is rare among high school football players in northeast Ohio. However, they believed that future investigations of CA-MRSA SSTIs risk factors should include both male and female athletes, sports other than football, and a large survey population. The military academy population had the characteristics to support such study.

33 CA-MRSA Infections in Children In 2007, Mercy Children’s Hospital in Toledo, Ohio experienced a six-fold increase in MRSA infection. This prompted McCullough et al. (2011) to conduct a retrospective, descriptive, single-cohort study to investigate the MRSA strain responsible for the incidence. Pediatric patients, 18 years old or younger, were selected for the study if they tested positive for MRSA. Bacterial culture specimens were tested at Mercy Children’s Hospital Clinical Laboratory. Molecular testing to identify the MRSA strain type was performed using Pulsed Field typing (PFT). Patients’ medical charts, dated June 1 through December 31, 2007, were reviewed for culture test results, socio-economic and demographic information to include prior exposure to the bacteria and previous hospitalization (McCullough et al., 2011). The medical charts’ review revealed that only 5 out of 63 cases of MRSA did not satisfy CDC clinical requirements for CA-MRSA. All 92% of CA-MRSA cases were associated with SSTI. 62% of patients with CA-MRSA infections were African American and 74% were socio-economically disadvantaged. Study results indicated a significant relationship, p