Rouse, Mark S.

ABSTRACT The activity of garenoxacin was compared to that of levofloxacin or penicillin in a rabbit model of Streptococcus mitis group (penicillin MIC, 0.125 μg/ml) and Streptococcus sanguinis group (penicillin MIC, 0.25 μg/ml) endocarditis. Garenoxacin and levofloxacin had MICs of 0.125 and 0.5 μg/ml, respectively, for both study isolates. Rabbits with catheter-induced aortic valve endocarditis were given no treatment, penicillin at 1.2 × 10 6 IU/8 h intramuscularly, garenoxacin at 20 mg/kg of body weight/12 h intravenously, or levofloxacin at 40 mg/kg/12 h intravenously. For both isolates tested, garenoxacin area under the curve (AUC)/MIC and maximum concentration of drug in serum ( C max )/MIC ratios were 368 and 91, respectively. Rabbits were sacrificed after 3 days of treatment; cardiac valve vegetations were aseptically removed and quantitatively cultured. For S. mitis group experimental endocarditis, all studied antimicrobial agents were more active than no treatment ( P < 0.001), whereas for S. sanguinis group endocarditis, no studied antimicrobial agents were more active than no treatment. We conclude that AUC/MIC and C max /MIC ratios may not predict activity of some quinolones in experimental viridans group endocarditis and that garenoxacin and levofloxacin may not be ideal choices for serious infections caused by some quinolone-susceptible viridans group streptococci.

ABSTRACT Due to increasing mupirocin resistance, alternatives for Staphylococcus aureus nasal decolonization are needed. Lauric acid monoesters combined with lactic, mandelic, malic, or benzoic acid are being evaluated as possible alternatives. We determined the in vitro activity of 13 lauric acid monoester (LAM) formulations and mupirocin against 30 methicillin-susceptible S. aureus (MSSA) isolates and 30 methicillin-resistant S. aureus (MRSA) isolates. We then used a murine model of MRSA nasopharyngeal colonization to compare the in vivo activity of mupirocin with three LAM formulations. MSSA and MRSA MIC 90 values were 0.25 μg/ml for mupirocin and ≤4 μl/ml for all LAM formulations tested. Hsd:ICR mice were challenged with 10 8 CFU/naris MRSA. Five days later, S. aureus colonization was documented by culture. Treatment with bland, mupirocin, or one of three LAM ointments was then administered unblinded thrice daily for 2 days. Three days after treatment, both anterior nares were cultured for S. aureus . Administration of 128774-49E or 128774-53A was associated with greater eradication of MRSA carriage (24/34 [71%] or 33/40 [83%]) of animals, respectively) than bland ointment (12/38 [32%]) ( P < 0.005). 128774-53A administration resulted in greater MRSA carriage eradication than mupirocin (19/38 [50%]) ( P < 0.005) in this model. LAM formulations warrant evaluation for S. aureus nasal decolonization in humans.

ABSTRACT Exposure of ciprofloxacin- and cefepime-susceptible Pseudomonas aeruginosa isolates to increasing concentrations of ciprofloxacin selected for ciprofloxacin resistance in 26/27 and cefepime nonsusceptibility in 7/27 isolates. Exposure of the isolates to increasing concentrations of cefepime selected for cefepime nonsusceptibility in 20/27 isolates but not for ciprofloxacin resistance.

ABSTRACT The pathophysiology of sepsis involves excessive lymphocyte apoptosis, which correlates with adverse outcomes, and disordered cytokine production, which may promote host injury. As the protease inhibitor (PI) class of antiretroviral agents is known to prevent apoptosis in vitro, we evaluated their effect on survival, lymphocyte apoptosis, and consequent cytokine production in mice with sepsis induced by cecal ligation and perforation. Mice pretreated with PIs have improved survival (67%; P <0.0005) compared with controls (17%) and a significant (P<0.05) reduction in lymphocyte apoptosis. Even mice receiving therapy beginning 4 h after perforation demonstrated improved survival (50%; P <0.05) compared with controls. PI therapy is also associated with an increase in the Th1 cytokine TNF‐a ( P <0.05) early in sepsis and a reduction in the Th2 cytokines IL‐6 and IL‐10 ( P <0.05) late in sepsis; despite no intrinsic antibacterial effects, PI also reduced quantitative bacterial blood cultures. The beneficial effects of PI appear to be specific to lymphocyte apoptosis, as lymphocyte‐deficient Rag1—/— mice did not experience benefit from treatment with PI. Thus, inhibition of lymphocyte apoptosis by PI is a candidate approach for the treatment of sepsis.— Weaver, J. G. R., Rouse, M. S., Steckelberg, J. M., Badley, A. D. Improved survival in experimental sepsis with an orally administered inhibitor of apoptosis. FASEB J. 18, 1185–1191 (2004)

ABSTRACT Studies that detected an association between Streptococcus bovis endocarditis and colon carcinoma have not taken into account the recently identified genetic diversity among organisms historically classified as S. bovis . With near full-length 16S ribosomal DNA sequence analysis, organisms cultured from the blood of endocarditis patients at the Mayo Clinic from 1975 to 1985 and previously identified as S. bovis or streptococcus group D nonenterococci were shown to represent S. bovis biotypes I (11 isolates) and II/2 (1 isolate), S. salivarius (1 isolate), and S. macedonicus (1 isolate). Two of the S. bovis biotype I cases were associated with colon cancer. Whether S. bovis biotype II or other organisms closely related to and historically identified as S. bovis (e.g., S. macedonicus ) are associated with malignant (or premalignant) colon lesions in humans remains to be definitively determined.

ABSTRACT We compared the activities of linezolid (25 mg/kg of body weight, administered intraperitoneally every 8 h) and of vancomycin (25 mg/kg of body weight, administered intraperitoneally every 8 h) in a rat model of vanA vancomycin-resistant Enterococcus faecium experimental endocarditis. Results were expressed as median log 10 CFU per gram of vegetation after 3 days of treatment. The median log 10 CFU per gram of vegetation was 10.1 among 7 untreated control animals, 10.2 among 9 vancomycin-treated animals, and 7.9 among 10 linezolid-treated animals. Linezolid treatment was more active ( P < 0.05) than vancomycin treatment or no treatment.

ABSTRACT The activity of trovafloxacin was compared with those of vancomycin and penicillin in a model of Streptococcus sanguis species group (trovafloxacin MIC, 0.125 μg/ml) and Streptococcus mitis species group (trovafloxacin MIC, 0.125 μg/ml) experimental endocarditis. Rabbits with catheter-induced aortic valve vegetations were given no treatment, trovafloxacin at 15 mg/kg of body weight three times a day (t.i.d.), vancomycin at 15 mg/kg twice a day, or penicillin at 1.2 × 10 6 IU t.i.d. After 3 days of treatment, the animals were sacrificed; cardiac valve vegetations were aseptically removed and cultured quantitatively. Penicillin was as active as vancomycin as measured by in vivo clearance of bacteria. Trovafloxacin was less active ( P < 0.05) than vancomycin or penicillin against S. sanguis species group infection but had similar efficacy against S. mitis species group infection. Quinolones, despite MICs in the susceptible range, may not be active for serious infections caused by some viridans group streptococci.

ABSTRACT The in vivo activity of linezolid or cefazolin against a clinical isolate of methicillin-susceptible Staphylococcus aureus (linezolid MIC, 2 μg/ml) was studied in a rat model of experimental osteomyelitis. Sixty rats with experimental S. aureus osteomyelitis were treated for 21 days with no antimicrobial, with 25 μg of linezolid per kg of body weight administered intraperitoneally twice or three times a day, or with 50 μg of cefazolin per kg administered intramuscularly three times a day. After treatment, the animals were sacrificed and the infected tibiae were processed for quantitative bacterial cultures. The results of treatment were expressed as log 10 CFU/gram of bone and analyzed by rank sum analysis. The results of linezolid treatment were not significantly different from those of untreated controls, while cefazolin treatment was significantly more active than no treatment or linezolid treatment.