Plasmid-related beta-lactamase production in Bacteroides fragilis strains

Res Microbiol. 2004 Dec;155(10):843-6. doi: 10.1016/j.resmic.2004.06.011.


Twenty Bacteroides fragilis group species isolated from children with and without diarrhea were analyzed. Antibiotic susceptibility was performed using an agar dilution method; beta-lactamase production was determined using a nitrocefin method, and plasmids were extracted using a commercial Miniprep System. MIC values ranged from 16 to 256 microg/ml for penicillin, 4-128 microg/ml for amoxicillin/clavulanic acid, 0.25-256 microg/ml for clindamycin, and 16-256 microg/ml for penicillin. beta-Lactamase was detected in all isolates. Only five isolates harbored plasmids varying from 7.8 to 1.8 kb. Loss of 6.4- and 3.8-kb plasmids in B. fragilis C68c was related to antibiotic resistance. Low molecular weight plasmids of 2.8-1.8 kb were stable. PCR amplification of cfiA and cepA genes was observed using total DNA, and the cfiA gene was also amplified from the 6.4-kb plasmid.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacteroides Infections / microbiology
  • Bacteroides fragilis / drug effects
  • Bacteroides fragilis / enzymology*
  • Bacteroides fragilis / genetics
  • Child
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • Diarrhea / microbiology
  • Drug Resistance, Bacterial / genetics
  • Humans
  • Microbial Sensitivity Tests
  • Plasmids / genetics
  • Polymerase Chain Reaction
  • beta-Lactamases / biosynthesis*
  • beta-Lactamases / chemistry
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism


  • Bacterial Proteins
  • DNA, Bacterial
  • beta-Lactamases
  • carbapenemase