RESUMO
The activity of MK-0826, a new carbapenem, against 309 Bacteroides fragilis group strains was investigated and compared with that of 11 other beta-lactam and 5 non-beta-lactam agents. MK-0826 showed excellent activity (MICs ranged from < or =0.06 to 4 microg/ml). The new carbapenem may be useful in the treatment of mixed anaerobic infections involving B. fragilis group strains.
Assuntos
Antibacterianos/farmacologia , Bacteroides fragilis/efeitos dos fármacos , Carbapenêmicos/farmacologia , Bacteroides fragilis/isolamento & purificação , Resistência Microbiana a Medicamentos , Humanos , Testes de Sensibilidade MicrobianaRESUMO
The in vitro activities of the new agents linezolid, quinupristin-dalfopristin, moxifloxacin, and trovafloxacin were determined and compared with those of penicillin, clindamycin, and four macrolides against 53 erythromycin-resistant Streptococcus pneumoniae, 117 S. pyogenes (64 erythromycin-susceptible and 53 -resistant), and 101 S. agalactiae (53 erythromycin-susceptible and 48 -resistant) isolates. Differentiation of macrolide resistance phenotypes was performed by the double-disk method. The genetic basis for macrolide resistance in 52 strains was also determined. The M phenotype was found in 84.9, 6.3, and 1.9% of S. pyogenes, S. agalactiae, and S. pneumoniae isolates, respectively. These strains were susceptible to miocamycin and clindamycin. Strains with the inducible phenotype accounted for 27.1% of S. agalactiae isolates and 9.4% each of S. pyogenes and S. pneumoniae isolates. All erythromycin-resistant isolates were also resistant to the 14- and 15-membered macrolides tested. Strains with all three phenotypes were susceptible to =2 microgram of linezolid per ml. Quinupristin-dalfopristin exhibited good in vitro activity against all strains, irrespective of their resistance to erythromycin (MICs at which 90% of the isolates tested were inhibited [MIC(90)s], 0.2 to 1 microgram/ml). Against the erythromycin-resistant S. pyogenes and S. agalactiae strains, moxifloxacin and trovafloxacin were the most active agents (MIC(90)s, 0.1 microgram/ml). The new antimicrobials evaluated may be alternative agents to treat infections caused by macrolide-resistant as well as macrolide-susceptible streptococci.
Assuntos
Antibacterianos/farmacologia , Compostos Aza , Fluoroquinolonas , Oxazolidinonas , Quinolinas , Streptococcus/efeitos dos fármacos , Acetamidas/farmacologia , Resistência Microbiana a Medicamentos/fisiologia , Quimioterapia Combinada/farmacologia , Eritromicina/farmacologia , Humanos , Linezolida , Testes de Sensibilidade Microbiana , Moxifloxacina , Naftiridinas/farmacologia , Oxazóis/farmacologia , Virginiamicina/farmacologiaRESUMO
BACKGROUND: The recent emergence of glycopeptide-resistant enterococci limits the treatment of enterococcal infections. The aim of this study was to evaluate the in vitro activity of a new streptogramin, quinupristin/dalfopristin, against 30 clinical isolates of vancomycin-resistant enterococci and compared with those of other 15 antimicrobials. MATERIAL AND METHODS: Enterococci were identified by using Rapid ID 32 Strep system. Genotyping of the isolates was performed by PCR. The MICs of quinupristin/dalfopristin were determined by the agar dilution technique recommended by the NCCLS. Susceptibilities to the rest of antibiotics tested (teicoplanin, ampicillin, penicillin, imipenem, doxycicline, chloramphenicol, gentamicin, streptomycin, rifampin, levofloxacin, fleroxacin, trovafloxacin, sparfloxacin, pefloxacin and clinafloxacin) were determined by using the E test. beta-lactamase production was examined with nitrocefin disks. RESULTS: Quinupristin/dalfopristin has demonstrated excellent activity against Enterococcus faecium (MIC90' 2 micrograms/ml). Enterococcus faecalis was considerably less susceptible than E. faecium, at concentration of 4 micrograms/ml inhibited only 31% of tested strains. For doxycicline 77% of strains were susceptible. Only five isolates were susceptible to clinafloxacin; the other quinolones tested displayed poor activity. Resistance to chloramphenicol was detected in 47% of isolates. None of the isolates produced beta-lactamase. CONCLUSIONS: This study indicates that vancomycin-resistant enterococci are often concomitantly resistant to multiple antibiotics. Quinupristin/dalfopristin was the most active agent tested against E. faecium strains. On the basis of these results quinupristin/dalfopristin could be a therapeutic option for the treatment of vancomycin-resistant E. faecium infections.
Assuntos
Antibacterianos/farmacologia , Enterococcus faecium/efeitos dos fármacos , Virginiamicina/análogos & derivados , Resistência Microbiana a Medicamentos , Resistência a Múltiplos Medicamentos , Infecções por Bactérias Gram-Positivas/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Resistência a Vancomicina , Virginiamicina/farmacologia , beta-Lactamases/análiseRESUMO
The antimicrobial activities of trovafloxacin, moxifloxacin, sanfetrinem, quinupristin-dalfopristin, and 14 other antimicrobial agents against 218 Bacteroides fragilis group strains were determined. A group of 10 imipenem-resistant strains were also tested. Imipenem, meropenem, and sanfetrinem had the lowest MICs of all of the beta-lactams. Quinupristin-dalfopristin inhibited all of the strains at 2 microg/ml. Overall, the MICs of trovafloxacin and moxifloxacin for 90% of the strains tested were 1 and 2 microg/ml, respectively.
Assuntos
Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Compostos Aza , Bacteroides fragilis/efeitos dos fármacos , Fluoroquinolonas , Lactamas , Naftiridinas/farmacologia , Quinolinas , Virginiamicina/farmacologia , Testes de Sensibilidade Microbiana , MoxifloxacinaRESUMO
The in-vitro activities of imipenem and four beta-lactam-beta-lactamase inhibitor combinations were tested against 816 strains of the Bacteroides fragilis group, and compared with other anti-anaerobic agents. None of the strains was resistant to metronidazole, and only one was resistant to chloramphenicol. Mezlocillin and piperacillin were moderately active, while clindamycin was the least active. Rates of resistance varied between various species. The new beta-lactam agents tested showed excellent activity; piperacillin-tazobactam and imipenem were the most active. The emergence of strains that are resistant to these agents, observed in this study, suggests there is a need to perform periodic antimicrobial susceptibility tests.
Assuntos
Antibacterianos/farmacologia , Bacteroides fragilis/efeitos dos fármacos , Amoxicilina/farmacologia , Ampicilina/farmacologia , Cefoxitina/farmacologia , Ceftizoxima/farmacologia , Cloranfenicol/farmacologia , Ácido Clavulânico/farmacologia , Clindamicina/farmacologia , Quimioterapia Combinada , Inibidores Enzimáticos/farmacologia , Imipenem/farmacologia , Metronidazol/farmacologia , Mezlocilina/farmacologia , Testes de Sensibilidade Microbiana , Ácido Penicilânico/análogos & derivados , Ácido Penicilânico/farmacologia , Penicilinas/farmacologia , Piperacilina/farmacologia , Especificidade da Espécie , Sulbactam/farmacologia , Tazobactam , Tienamicinas/farmacologia , Ticarcilina/farmacologia , Inibidores de beta-LactamasesRESUMO
We studied the evolution of susceptibility of Streptococcus pyogenes isolated in our hospital from 1987 to 1996. Susceptibility to penicillin, ampicillin, cefotaxime, cefuroxime, imipenem, erythromycin, clindamycin, tetracycline, vancomycin, ciprofloxacin, rifampin, and chloramphenicol was determined by the National Committee for Clinical Laboratory Standards broth microdilution method. Differentiation of phenotypes of erythromycin-resistant strains was performed using the double-disc method. All isolates remained very susceptible in vitro to penicillin and all of the other beta-lactam agents tested. Between 1987 and 1995 the incidence of erythromycin resistant strains remained below 5%; the difference in the resistance rate between 1995 (2.6%) and 1996 (17.1%) was statistically significant. The macrolide resistance M phenotype was the most frequent. The isolation rates of tetracycline-resistant strains increased from 2.2% in 1987 to 11.2% in 1988. The marked increase in the incidence of erythromycin resistance observed in our area warrants periodic surveillance of antibiotic susceptibility of S. pyogenes isolates and emphasizes the need to control outpatient antibiotics. The preponderance of the M phenotype may have implications in the choice of antibiotic.