animals. For S. aureus, the doses required to clear the infection in 50% of mice were as follows: sparfloxacin,. 10 mg/kg/day; ciprofloxacin, 33 mg/kg/day; and ...
Vol. 36, No. 2
ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, Feb. 1992, p. 505-507
0066-4804/92/020505-03$02.00/0
Antibacterial Activity of Sparfloxacin against Experimental Renal Infections in Mice A. GEORGOPOULOS,* S. M. FEISTAUER, W. GRANINGER, S. PFLEGER, AND M. GEORGOPOULOS
Clinical Department for Infectious Diseases and Chemotherapy, University Clinic for Internal Medicine I, A-1090 Vienna, Austria Received 8 July 1991/Accepted 7 December 1991
In a murine model of renal infection (Staphylococcus aureus and Escherichia colt), sparfloxacin was compared with ciprofloxacin and fleroxacin. After intrarenal inoculation, mice were treated orally for 5 days. The drugs were administered at five different dosages, ranging from 3.125 to 50 mg/kg of body weight per day for S. aureus and from 0.78 to 12.5 mg/kg/day for E. coli. Evaluation of efficacy was based on the proportional reduction of bacterial counts in the kidney tissues of treated animals compared with those of untreated control animals. For S. aureus, the doses required to clear the infection in 50% of mice were as follows: sparfloxacin, 10 mg/kg/day; ciprofloxacin, 33 mg/kg/day; and fleroxacin, 16 mg/kg/day. For E. coli renal infection, the corresponding dosages were as follows: sparfloxacin, 1.5 mg/kg/day; ciprofloxacin, 2.45 mg/kg/day; and fleroxacin, 1.8 mg/kg/day. Sparfloxacin and fleroxacin have a lower effective dose than ciprofloxacin in these models, probably because ciprofloxacin has a shorter serum half-life than the other two compounds.
Sparfloxacin is a new quinolone with broad and potent in vitro antibacterial activity against gram-positive microorganisms such as staphylococci, streptococci, and enterococci. It is also effective against gram-negative organisms such as members of the family Enterobacteriaceae, Pseudomonas spp., Haemophilus influenzae, and various species of mycoplasmas, legionellas, chlamydiae, and mycobacteria (1, 3, 6, 9, 10). The in vitro antibacterial activity of sparfloxacin against gram-positive cocci exceeds that of ciprofloxacin or fleroxacin, and it is as efficacious as ciprofloxacin and fleroxacin against members of Enterobacteriaceae and nonfermenters (1, 10). Sparfloxacin is well absorbed orally. It has a relatively long half-life in plasma and shows good tissue distribution (13). The efficacy of sparfloxacin was examined and compared with those of fleroxacin and ciprofloxacin by using a well-standardized murine renal abscess model (2, 4). Drugs. Sparfloxacin was obtained from Rhone-Poulenc Sante, Paris, France, fleroxacin was obtained from Hoffmann-La Roche, Vienna, Austria, and ciprofloxacin was obtained from Bayer, Vienna, Austria. For oral administration, the compounds were suspended in 0.2% aqueous carboxymethylcellulose. Organisms. Clinical isolates of methicillin-resistant Staphylococcus aureus (1290) and Escherichia coli (12090) were used. The organisms were stored at -196°C in liquid nitrogen and thawed at 37°C for 2 to 3 min before inoculation. Assessment of in vivo activities. National Medical Research Institute female mice weighing 18 to 20 g were obtained from Gassner Animal Farms, Munich, Germany. Ten animals were allocated to each dosage regimen. Mice under ether anesthesia were infected intrarenally (right kidney) after transperitoneal flank incision. The inoculum was a suspension of 0.02 ml containing 5 x 105 CFU of S. aureus per ml and 104 CFU of E. coli per ml; the suspensions were made of physiological saline from soy broth cultures. Drugs were administered orally for a period of 5 days, twice a day with an interval of 5 to 6 h, at doubling dosages
ranging from 0.78 to 12.5 mg/kg of body weight per day for E. coli and from 3.125 to 50 mg/kg/day for S. aureus. Ten untreated animals with renal infection served as a control group. Animals were sacrificed 2 days after the end of treatment, and the infected kidneys were homogenized. The number of viable organisms (CFU per gram) was determined by agar plating. The proportional reduction of bacteria in treated animals was calculated as 100 x V/n ims, where I is the total score of animals in the treatment group, n is the number of animals in this group, and ms is the maximum score (i.e., 4). The scores were assigned as follows: decrease in CFU/g of tissue by 100- to 1,000-fold, 0; decrease in CFU/g of tissue by 1,000- to 10,000-fold, 1; decrease in CFU/g of tissue by 100,000-fold, but with bacteria still present, 2; tissue free of bacteria, 4. The evaluation of therapeutic efficacy was based on the
S . AUREUS 9
8 7-
6 5
A
DRUG
4.
e
COLOXAOCIN
N
FLEROXACIN 3
-
* CONTROL
-A-
156
~LRFOXACIN
313
625
1250
250 0
5 )00
DOSE (mgg body eight)
FIG. 1. Therapeutic efficacies of sparfloxacin, fleroxacin, and ciprofloxacin against S. aureus. Ten animals were used for each dosage of the drugs and for the control group. Similar results were
obtained in two other experiments.
*
A, %
Corresponding author. 505
506
NOTES
ANTIMICROB. AGENTS CHEMOTHER.
S AUREUS
E.COLI
.
-a $
8-
C
FLECIN
6.J
FLER3XACINj SPARFUACIN
.E
4 ~ ~ ~ ~ ~
~
~ ~ ~ ~ ~ 3.
~
o
~ ~ ~ ~~DS E~k 2-weg
z
Cl 2.
FL OP
Cl
a
FL
aureus
~
~
~
~
~
~
~
~~~~~~~~'
~
~
~
~
~
~
~
~
D05E
-
FL OP
sparfioxacin, fieroxacin, in relation to dosage.
Bactericidal effects of
rofloxacin against S.
~
~
6 1 32 J-620 25 4 1 '441-
a
FL OP
~
FL OP and cip-
proportional reduction of bacterial counts in the kidney tissue in treated animals compared with that of untreated animals. Statistical evaluation. The data obtained were used to calculate 50% effective doses (doses that reduce the numbers of log CFU/g of kidney tissue by 50%) with 95% confidence limits by applying the Spearman-Karber method and the Wilcoxon test (7, 8, 12). For S. aureus, the MIC of sparfloxacin was 0.25 mg/liter, the MIC of fleroxacin was 0.5 mg/liter, and the MIC of ciprofloxacin was 0.25 mg/liter; for E. coli, the MIC was 0.25 mg/liter for all tested quinolones. The results obtained for S. aureus infection are summarized in Fig. 1 and 2. Figure 1 shows the reduction in CFU/g of kidney tissue for animals treated with the three trial substances compared with the corresponding values observed for the control group. The results are suggestive of dose-dependent therapeutic efficacy. A significant difference between the antibacterial activities of sparfloxacin and ciprofloxacin and between those of fleroxacin and ciprofloxacin E. COLJ
DOSE
(mkgf bodwev
FIG. 4. Bactericidal effects of sparfloxacin, fleroxacin, and ciprofloxacin against E. coli in relation to dosage.
(P < 0.01) was observed, although no difference between those of sparfloxacin and fleroxacin was observed. Compared with the bactericidal activities of fleroxacin and ciprofloxacin (Fig. 2), the in vivo effect of sparfloxacin against methicillin-resistant S. aureus is more pronounced even at a low dosage (3.125 mg/kg/day). Figures 3 and 4 comparatively illustrate the in vivo activities of sparfloxacin, fleroxacin, and ciprofloxacin against E. coli. Dose-dependent therapeutic efficacy is evident with all trial substances (Fig. 3). Even at a low dosage, the quinolones show a bactericidal effect against gram-negative microorganisms (Fig. 4). The doses required to eliminate infection in 50% of the mice in the S. aureus model were as follows: sparfloxacin, 10 mg/kg/day; fleroxacin, 16 mg/kg/day; and ciprofloxacin, 33 mg/kg/day. In the E. coli model, the corresponding figures were as follows: sparfloxacin, 1.5 mg/kg/day; fleroxacin, 1.8 mg/kg/day; and ciprofloxacin, 2.5 mg/kg/day (Table 1). Recently developed fluoroquinolone antibacterial agents such as ciprofloxacin, fleroxacin, and sparfloxacin show broad-spectrum antibacterial activities (6, 9, 10). Sparfloxacin is well absorbed orally, with good distribution in tissue and long half-life in plasma (10, 13). The antibacterial activity and the pharmacokinetic properties of sparfloxacin suggest that this compound is effective against infections with various pathogens. All new quinolones tested were efficacious in this animal model of renal infections with E. coli. Sparfloxacin was more effective than ciprofloxacin against infections with methicillin-resistant S. aureus. The pharmacokinetics profile of TABLE 1. Comparative activities of sparfloxacin, fieroxacin, and ciprofloxacin against renal infection in mice Clearance
Compound 0390
0.781
13563
DOSE (mg&g bod
3.12
6.250
12uSO
y
FIG. 3. Therapeutic efficacies of sparfloxacin, fleroxacin, and ciprofloxacin against E. coli. Ten animals were used for each dosage of the drugs and for the control group. Similar results were obtained in two other experiments.
Sparfloxacin Fleroxacin Ciprofloxacin
ED"0a
E. coli
S. aureus
1.54 (1.05-2.25) 1.79 (1.23-2.63) 2.45 (1.64-3.67)
9.81 (5.85-16.44) 15.93 (10.44-24.31) 32.99 (22.37-48.64)
a ED50, 50%o effective dosage (with 95% confidence interval), expressed in micrograms per kilogram of body weight per day. Values presented are means, followed by ranges in parentheses.
VOL. 36, 1992
sparfloxacin and fieroxacin (longer serum half-lives [5 to 4.6 h] than that of ciprofloxacin [1.6 to 2 h] in mice) could explain these results. Nosocomial infections caused by methicillin-resistant S. aureus have become an increasing problem. Their treatment is usually difficult because of the resistance of the organism to most available antibacterial agents (5, 11, 14). Other authors have also found sparfloxacin to be highly active against both methicillin-resistant and methicillin-sensitive S. aureus (9, 10). Good efficacy in renal infection with E. coli has been demonstrated for all trial fluoroquinolones. Sparfloxacin seems to be beneficial in the treatment of nosocomial infections of the renal parenchyma, e.g., septicemia with metastatic renal foci caused by methicillin-resistant S. aureus.
REFERENCES 1. Bille, J., and M. P. Glauser. 1990. In vitro activity of sparfloxacin (AT4140) compared with that of three other quinolones against 433 clinical isolates, abstr. 1199. Program Abstr. 30th Intersci. Conf. Antimicrob. Agents Chemother. 2. Georgopoulos, A., W. Graninger, S. Breyer, S. Pfleger, and M. Georgopoulos. 1990. Sparfloxacin in renal infection in mice, abstr. 1246. Program Abstr. 30th Intersci. Conf. Antimicrob. Agents Chemother. 3. Hashimoto, M., A. Minami, K. Nakata, Y. Sakaguchi, T. Kojima, K. Fujimoto, H. Yoshida, S. Nakamura, K. Ohnishi, and M. Shimizu. 1988. Antibacterial and toxicological properties of AT-4140, abstr. 1488. Program Abstr. 28th Intersci. Conf. Antimicrob. Agents Chemother. 4. Hirschl, A., G. Stanek, M. Rotter, A. Georgopoulos, and S. Breyer. 1985. Zur Wirksamkeit von N-Formimidoyl-Thienamycin gegenuber methicillinempfindlichen und -resistenten Stammen von Staphylococcus aureus. Zeitschr. Antimicrob. Antineopl. Chemoth. 3:1-7.
NOTES
507
5. Hooper, D. C., and J. S. Wolfson. 1985. The fluoroquinolones: pharmacology, clinical uses, and toxicities in humans. Antimicrob. Agents Chemother. 28:716-721. 6. Kojima, T., M. Inoue, and S. Mitsuhashi. 1989. In vitro activity of AT-4140 against clinical bacterial isolates. Antimicrob. Agents Chemother. 33:1980-1988. 7. Litchfield, J. T., and F. Wilcoxon. 1949. A simplified method of evaluating dose-effect experiments. J. Pharmacol. Exp. Ther. 96:99-113. 8. Miller, L. C., and M. L. Tainter. 1944. Estimation of the ED50 and its error by means of logarithmic probit graph paper. Proc. Soc. Exp. Biol. Med. 57:261-264. 9. Nakamura, S., T. Minaumi, T. Kojima, K. Fujimoto, N. Kurobe, S. Kashimoto, T. Ohne, K. Kuono, M. Hashimoto, and M. Shimizu. 1988. AT-4140, a new broad spectrum quinolone, abstr. 1487. Program Abstr. 28th Intersci. Conf. Antimicrob. Agents Chemother. 10. Nakamura, S., A. Minami, K. Nakata, N. Kurobe, K. Kouno, Y. Sakaguchi, S. Kashimoto, H. Yoshida, T. Kojima, T. Ohue, K. Fujimoto, M. Nakamura, M. Hashimoto, and M. Shimizu. 1989. In vitro and in vivo antibacterial activities of AT-4140, a new broad-spectrum quinolone. Antimicrob. Agents Chemother. 33: 1167-1173. 11. Piercy, E. A., D. Barbaro, J. A. Luby, and P. A. Mackowiak. 1989. Ciprofloxacin for methicillin-resistant Staphylococcus aureus infections. Antimicrob. Agents Chemother. 33:128-130. 12. Reed, L. J., and H. Muench. 1938. A simple method of estimating fifty percent end points. Am. J. Hyg. 27:493-497. 13. Sekine, Y., Y. Matsunaga, H. Miyazaki, T. Yamaguchi, Y. Mizuki, T. Itoh, N. Kurobe, S. Nakamura, M. Hashimoto, and M. Shimizu. 1988. Absorption, distribution, metabolism and excretion of AT-4140 in animals, abstr. 1489. Program Abstr. 28th Intersci. Conf. Antimicrob. Agents Chemother. 14. Wolfson, J. S., and D. C. Hooper. 1985. The fluoroquinolones: structures, mechanisms of action and resistance, and spectra of activity in vitro. Antimicrob. Agents Chemother. 28:581-586.
