Journal of Antimicrobial Chemotherapy (1987) 20, 477-488
© 1987 The British Society for Antimicrobial Chemotherapy
research-article |
The antibiotic sensitivity of the Bacteroides fragilis group in the United Kingdom
United Medical and Dental Schools of Guy's and St Thomas's Hospitals, St Thomas' Hospital London SE1 7EH, U.K.
accepted 4 April 1987
aCorresponding author
Eight hundred and sixty-two cultures of penicillin-resistant anaerobic Gramnegative bacilli collected from 14 centres in the United Kingdom were identified. Six hundred and fifty-one were members of the Bacteroides fragilis group, and their sensitivity to 14 antibiotics was determied by a microtitre method.
Among the ß-lactams, moderate resistance to ampicillin (MIC
8 mg/l) was common (B. ovatus 100%, B. thetaiotaomicron 95%, B. fragilis 76%, B. distasonis 50%, B. vulgatus 25%) but high-level resistance (MIC > 128 mg/l) was uncommon (B. fragilis 4 %, B. ovatus 4%, B. vulgatus 3%). In B. fragilis, moderate resistance to other ß-lactams was less common (cefoxitin 16%, mezlocillin 13% and cefotetan 7%), though in most non-B. fragilis species, higher numbers were moderately resistant. High level resistance to these three ß-lactams was rare. Resistance to penems (MIC >4 mg/l) was not detected.
All isolates of B. fragilis tested were sensitive to 16 mg/l of ciprofloxacin and ofloxacin, and 68% and 81% of isolates were sensitive to < 4 mg/l, but one isolate of B. uniformis and one of B. thetaiotaomicron proved highly resistant. Clindamycin resistance was uncommon (1% of B. fragilis and 10% other B. fragilis group isolates were resistant to 2 mg/l clindamycin) with isolates resistant to clindamycin often also resistant to erythromycin. Tetracycline resistance was common in all species and occurred in 40% of isolates. Resistance to chloramphenicol, metronidazole or rifampicin was not detected.
Significant differences were observed between the sensitivity ofB. fragilis and other members of the B. fragilis group to mezlocillin, cefotetan, cefoxitin and the quinolones. There was no clear trend towards higher resistance in any one area of the country.