Annual incidence, epidemiology, and comparative in vitro susceptibilities to cefoxitin, cefotetan, cefmetazole, and ceftizoxime of recent community-acquired isolates of the Bacteroides fragilis group

Abstract

The six species of the Bacteroides fragilis group are potent pathogens and commonly have different susceptibility patterns. We determined the relative annual isolation rate of anaerobic bacteria and the susceptibility of B. fragilis group species isolated during 1987 at two community hospitals. The relative frequencies of isolation of 261 strains were as follows: B. fragilis, 61%; B. thetaiotaomicron, 17%; B. distasonis, 7%; B. vulgatus, 6%; B. ovatus, 5%; and B. uniforms, 4%. A total of 234 recent clinical isolates were tested against cefmetazole, cefotetan, cefoxitin, ceftizoxime, clindamycin, imipenem, and piperacillin by a brucella agar dilution method. Imipenem was the most active agent tested with all but three isolates (two B. vulgatus and one B. distasonis) susceptible to <2 ,ug/ml. Of the cephalosporins tested, cefoxitin, cefotetan, and cefmetazole were relatively equal against B. fragilis, with 93 to 98 % of strains susceptible to 32 ,ug/ml. Ceftizoxime was less active, with an MIC for 90% of strains tested of 128 ,ug/ml and only 75% of isolates susceptible to 32 Fg/ml. Against B. ovatus, B. vulgatus, B. thetaiotaomicron, and B. uniforms, cefoxitin showed a twoto threefoldsuperior activity compared with that of cefotetan and cefmetazole. In general, ceftizoxime was much less active, except against B. distasonis, for which 78% of isolates were susceptible to 32 ,ug/ml compared with 68% for cefoxitin, 19% for cefmetazole, and 16% for cefotetan. Clindamycin and piperacillin showed activity similar to that of cefoxitin, except piperacillin was less active versus B. vulgatus and B. distasonis. We therefore suggest that clinical laboratories determine the species of B. fragilis group isolates as well as perform susceptibility studies on these isolates. Clinicians should be aware that while B. fragilis is the most frequent isolate, 38% of isolates are from other, more resistant B. fragilis group species.

Antimicrobial Stewardship Opportunities in Patients with Bacteremia Not Identified by BioFire FilmArray

“…In our study, only 6% of organisms could not be identified by BioFire BCID since they were not found on the panel. The spectrum of causative pathogens and the sources of infection for the NB-PC group in our study corresponded to that reported in the literature (18)(19)(20). In our study, the organisms from the NB-PC cohort that were determined to be true pathogens were mostly Bacteroides spp., followed by Clostridium and Fusobacterium spp.…”

Five-year retrospective epidemiological survey of anaerobic bacteraemia in a University Hospital and Review of the Literature

“…The occurrence of anaerobic and aerobic bacteraemias at the University Hospital Basel (UHBS), Switzerland, was estimated, and the proportions of six important groups of anaerobes in relation to 1000 blood cultures as well as in relation to positive aerobic blood culture results over a 10-year period were analyzed [17]. [18] determined the relative annual isolation rate of anaerobic bacteria and the susceptibility of B. fragilis group species isolated during 1987 at two community hospitals in Los Angeles, California, US. The relative frequencies of isolation of 261 strains were as follows: B. fragilis, 61%; B. thetaiotaomicron, 17%; B. distasonis, 7%; B. vulgatus, 6%; B. ovatus, 5%; and B. uniformis, 4%.…”

Short prereduced anaerobically sterilized (PRAS) biochemical scheme for identification of clinical isolates of bile-resistant Bacteroides species

“…The relative frequencies that the various species were encountered at the Wadsworth Veterans Administration Medical Center are presented in Table 1. The data presented in Table 1 for the R. M. Alden Research Laboratory were compiled in a previous study (9).…”

“…Anaerobes are potent opportunistic pathogens and can be isolated from any type of infection. More than one-third of all anaerobes isolated from clinical specimens are members of the Bacteroides fragilis group, and the species B. fragilis is the anaerobe most frequently isolated from blood cultures (9). The pathogenicity of the B. fragilis group is related to a variety of virulence factors, including proteolytic and hydrolytic enzymes and capsules that differ among Bacteroides species (3,15,19,22).…”