Increasing Trends in Antimicrobial Resistance among Clinically Important Anaerobes and Bacteroides fragilis causing Nosocomial Infections: Emerging Resistance to Carbapenems. Antimicrobial agents and chemotherapy [Antimicrob Agents Chemother] Journal article

This study reported on the data of susceptibility of five commonly used anti-anaerobic agents to five clinically frequently encountered anaerobes from 2000 to 2007 and to Bacteroides fragilis isolates causing nosocomial infections from 1990 to 2006. There was a trend of decreasing susceptibilities to ampicillin-sulbactam, cefmetazole, chloramphenicol. and clindamycin with time to these anaerobes during the study period. Rates of susceptibility to clindamycin and cefmetazole for all clinical isolates of Bacteroides fragilis isolates were higher than those of isolates associated with nosocomial infections. Minimum inhibitory concentrations (MICs) of 207 anaerobic blood isolates collected in 2006 to 14 antimicrobial agents were determined by the agar dilution method. The non-susceptibility rates to imipenem (meropenem) was 7% (12%) for B. fragilis (n=60), 7% (3%) for B. thetaiotamicron (n=30), 4% (4%) for Fusobacterium species (n=27), 6% (0%) for Prevotella species (n=16), 15% (0%) for Clostridium species (n=28), and 0% (0%) for Peptostreptococcus species (n=32). The susceptibility rate to moxifloxacin was 90% for B. fragilis, 87% for B. thetaiotaomicron, 81% for Fusobacterium species, 75% for Prevotella species, 93% for Clostridium species, and 78% for Peptostreptococcus species. Thirty-six percent of Clostridium species and 12% of Peptostreptococcus species were not susceptible to metronidazole. Comparison of data with a previous survey from the same institute in 2002 revealed the higher rates of nonsusceptibility to carbapenems especially for B. fragilis, Fusobacterium species, and Prevotella species isolates. The high rates of nonsusceptibility to commonly used anti-anaerobic agents mandate our attention and periodic monitoring the trend of the resistance is crucial.

Antimicrobial agents and chemotherapy [Antimicrob Agents Chemother]