Disseminated nocardiosis in an elderly patient presenting with prolonged pyrexia: Diagnosis by thyroid abscess culture. Indian J Med Microbiol. 2007; 25: 294-6.
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Nocardaemia in an Immunocompetent Individual Medha Y Rao*, Indumathi VA**, Ranjit Mohan***, Anil Kumar T****, Punith K*****
Abstract Nocardiosis most often occurs as an opportunistic infection in an immunocompromised host. Systemic infections with Nocardia species continue to be a serious threat to the immunosuppressed. Diagnosis can be difficult due to the protean manifestations. However, reports of isolation of Nocardia from the blood cultures of immunocompetent patients are limited. We report a case of a 26-year-old previously healthy adult male presenting with signs of encephalitis from which Nocardia asteroides was isolated in the blood culture. The primary focus of infection could not be identified. This case is being reported for its rarity of occurrence and unusual manifestation.
Introduction Classically, the isolation of Nocardia species from blood cultures has been considered as indicating disseminated infection. Literature review of Nocardiosis is limited, especially on the blood stream infections1. Although disseminated nocardiosis is presumed to occur via haematogenous spread from the primary focus of infection, capture of the organism from the blood culture is unusual. Bacteraemia is an uncommon presentation in a normal individual and rarely reported.
Case report A 26-year-old male presented with history of fever with chills and rigors since 3 days, altered sensorium and recurrent episodes of generalised tonic clonic convulsions since one day. The patient was hospitalised with the above complaints for a day in a local nursing home and had received IV fluids and antibiotics (third generation cephalosporin). His sensorium deteriorated over the course of the day. Oxygen saturation dropped and he became progressively hypotensive with recurring episodes of generalised tonic clonic seizures. He was referred to our critical care unit for further management. There was recent history of travel for recreational activity to a forest area. On examination, the patient was febrile (99° F) and in altered sensorium (Glasgow Coma Scale E3 V1 M5). His heart rate was 100/min; BP recorded at 80/60 mmHg, SpO2
92%. Viral encephalitis and cerebral malaria were considered among the differential diagnoses. Chest X-ray, MR angiogram, and CT brain were normal. Lab investigations showed a total count of 18,000/dl with polymorph predominance. Tests for febrile conditions, such as blood smear for malarial parasite, antibody tests for dengue, leptospira, enteric fever, and brucellosis were found negative. CSF analysis showed a cell count of 20, mostly lymphocytes, proteins 83.4 mg/dl and glucose of 109.3 mg/dl. Gram’s stain, India ink preparation, bacterial antigens and cultures were negative for bacterial pathogens. Viral screen for encephalitis and tuberculosis were negative. Other routine laboratory parameters were within normal limits.The patient was completely evaluated for an underlying immuno-suppressive condition that included HIV testing and was found to be negative. In view of deteriorating sensorium and low oxygen saturation, an elective endotracheal intubation was done for airway protection and ventilation. The patient was empirically prescribed ceftriaxone, amikacin, and artesunate. Blood culture sent on the admission day yielded Nocardia asteroides after 40 hours. The patient continued to receive the antibiotics that were started empirically and his clinical condition improved rapidly over a period of one week and he was discharged on oral linezolid for a period of 6 weeks. Follow-up blood cultures remained sterile 2 weeks and 6 weeks following discharge.
* Professor and Head, *** Post-graduate, **** Professor, MS Ramaiah Medical Teaching Hospital, MSRIT Post, New BEL Road, Bengaluru - 560 054, ***** Resident, Department of Medicine, MS Ramaiah Memorial Hospital, Bengaluru - 560 054, ** Professor in Microbiology, Head, Gokula Metropolis Labs, MS Ramaiah Memorial Hospital, Bengaluru - 560 054.
Discussion Nocardia species comprised 0.003% of all positive blood cultures from one hospital review2. Nocardaemia is likely to occur in patients with concomitant malignancy and frequent use of central venous catheters. Pulmonary disease usually accounts for the origin of nocardaemia2. Manifestations of nocardiosis associated with bacteraemia include psoas abscess3, pneumonia with or without abscess, or pleural effusion4-7, cutaneous or subcutaneous nodules, brain abscess, septic arthritis with myositis, catheter tip infection, intra-abdominal abscess. Disseminated nocardaemia cases have been reported in immunocompromised patients in India and worldwide8,9,10. However, reports of such disseminated norcardaemia in an immunocompetent individual is limited11-14. Our patient was a normal healthy young adult with no underlying immunosuppressive disorders. No primary focus of infection could be identified. Hypothesis to explain the rarity of documenting bacteraemia include co-infection with a more resilient organism, infrequent and intermittent bacteraemia, and failure to retain blood cultures for sufficient time to allow for detectable growth to occur. Blood cultures positive for Nocardia species may represent contamination more often than originally recognised2, 3. However, under-reporting of this phenomenon may occur as cultures positive for Gram-positive rods are thought to be Corynebacterium species and are discarded without identification. Fatal cases without therapy and relapse in nocardaemia have been reported15. In a review of 29 patients with Nocardiosis, the authors found that 4 out of the 5 nocardaemic patients who did not receive antibiotic therapy died and one with asymptomatic. Nocardaemia had recurrence of active infection 2 months later. Therefore the significance of nocardaemia in this situation is still a clinical judgement and it cannot be disregarded as a contaminant. Our patient gave a history of visit to a forest area and an exposure to heavily wooded environment while constructing a raft to participate in a competition. High infective dose of the organism inhaled/ inoculated during this process and further dissemination
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into the blood stream is a point to be considered for the source of infection. Intermittent nocardaemia and capturing the organism in the blood – although a rare event – should be considered even in an immunocompetent individual. In addition to the difficulty in culture, the identification of Nocardia species is labour intensive and is not performed routinely in service labs. Thus the actual prevalence may be underestimated1. In conclusion, although nocardaemia occurs in immunocompromised patients, isolation of this organism from the blood stream is a possibility in the immunocompetent. Protean presentation of the disease is well known in both the immunocompromised and immunocompetent. It is essential to extend the period of incubation for blood cultures in order to pick-up the slow growing species of Nocardia. Every Gram-positive bacilli that looks like Corynebacterium should be processed for Nocardia so that we do not under-report or underestimate the occurrence of this infection. In order to avoid recurrence, long-term course of an antibiotic effective against Nocardia needs to considered.
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