title: Antibiotic susceptibility of anaerobic bacteria with special reference to Bacteroides fragilis.
abstract: It was shown that recent Swedish clinical isolates of anaerobic bacteria are susceptible to many antibiotics by the agar dilution method with the exception of the Bacteroides group versus beta-lactam antibiotics or tetracyclines. Strains of B. fragilis were inhibited by 4--greater than 128 micrograms benzylpenicillin or cephalothin/ml, 1.0--64 micrograms cefoxitin/ml, 0.064--2 micrograms clindamycin or metronidazole/ml, 2--8 micrograms chloramphenicol/ml, 2--16 micrograms fusidic acid/ml and 0.032--32 micrograms doxycycline/ml. Resistance to beta-lactam antibiotics was partly due to the production of beta-lactamase. Growth of beta-lactamase producing strains in the presence of enzyme inhibitors such as clavulanic acid or CP-45899 together with cephaloridine lowered the MIC's manyfold. Cefoxitin with relative resistance to beta-lactamases inhibited the majority of the strains at 8 micrograms/ml. Cefoxitin-resistant strains (MIC greater than or equal to 16 micrograms/ml) were also resistant to the new cephalosporins BL-S786 and HR-756 as well as to the new cefamycins A, B, CL619-183, CS-1170 and Sq-14359 and to thienamycin. Cefamycin CL619-183, only showed a slightly higher in vitro activity than cefoxitin. Resistance to the cefamycins could not be correlated to the production of beta-lactamases.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001441:Bacteroides fragilis / Q000187:drug effects* / Q000201:enzymology; D002509:Cephaloridine / Q000494:pharmacology; D003013:Clostridium / Q000187:drug effects* / Q000201:enzymology; D004352:Drug Resistance, Microbial; D005673:Fusobacterium / Q000187:drug effects / Q000201:enzymology; D006089:Gram-Negative Anaerobic Bacteria / Q000187:drug effects* / Q000201:enzymology; D008795:Metronidazole / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D001443:Prevotella melaninogenica / Q000187:drug effects / Q000201:enzymology; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D065093:beta-Lactamase Inhibitors; D008795:Metronidazole; D001618:beta-Lactamases; D002509:Cephaloridine