title: Increasing trends in antimicrobial resistance among clinically important anaerobes and Bacteroides fragilis isolates causing nosocomial infections: emerging resistance to carbapenems.
abstract: This study reports data on the susceptibilities to five commonly used antianaerobic agents of 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 of these anaerobes to ampicillin-sulbactam, cefmetazole, chloramphenicol, and clindamycin with time during the study period. The 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. The MICs of 207 anaerobic blood isolates collected in 2006 to 14 antimicrobial agents were determined by the agar dilution method. The rates of nonsusceptibility to imipenem and meropenem were 7% and 12% for B. fragilis isolates (n = 60), 7% and 3% for Bacteroides thetaiotamicron isolates (n = 30), 4% and 4% for Fusobacterium species (n = 27), 6% and 0% for Prevotella species (n = 16), 15% and 0% for Clostridium species (n = 28), and 0% and 0% for Peptostreptococcus species (n = 32). The rates of susceptibility to moxifloxacin were 90% for B. fragilis isolates, 87% for B. thetaiotaomicron isolates, 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 the data with the data from a previous survey from the same institute in 2002 revealed higher rates of nonsusceptibility to carbapenems, especially for B. fragilis, Fusobacterium species, and Prevotella species isolates. The high rates of nonsusceptibility to commonly used antianaerobic agents mandate our attention, and periodic monitoring of the trend of the resistance is crucial.
authors.affiliation: Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Chia-Ying
authors.initials: CY
authors.lastname: Liu
authors.forename: Yu-Tsung
authors.initials: YT
authors.lastname: Huang
authors.forename: Chun-Hsing
authors.initials: CH
authors.lastname: Liao
authors.forename: Li-Ching
authors.initials: LC
authors.lastname: Yen
authors.forename: Hsiu-Ying
authors.initials: HY
authors.lastname: Lin
authors.forename: Po-Ren
authors.initials: PR
authors.lastname: Hsueh
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001421:Bacteria, Anaerobic / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D001442:Bacteroides Infections / Q000453:epidemiology / Q000382:microbiology; D001441:Bacteroides fragilis / Q000187:drug effects* / Q000302:isolation & purification; D001769:Blood / Q000382:microbiology; D015780:Carbapenems / Q000494:pharmacology*; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests; D013624:Taiwan / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems