Augmentation effect of clavulanic acid with penicillin, cephalothin and ticarcillin against Bacteroides fragilis.
The effect of clavulanic acid on the in vitro activity of beta-lactam antibiotics against Bacteroides fragilis (154 strains) was tested. The MIC90 on 154 strains of B. fragilis tested was greater than 64 micrograms/ml for penicillin and cephalothin, and greater than 128 for ticarcillin alone. 32 strains of B. fragilis relatively resistant to the test beta-lactam antibiotics (most of them beta-lactamase producers) were retested with the addition of clavulanic acid. 90% of the strains were then inhibited by less than or equal to 8 micrograms/ml of penicillin and cephalothin, and by 32 micrograms/ml of ticarcillin. The strongest beta-lactamase producers were the most susceptible, and this was not influenced by change in pH of the diluent for clavulanic acid from 6.0 to 7.4. Both penicillin and cephalothin when combined with clavulanic acid were highly effective against B. fragilis but the therapeutic relevance of these combinations remains to be evaluated.
D001441:Bacteroides fragilis / Q000187:drug effects*; D002512:Cephalothin / Q000494:pharmacology*; D019818:Clavulanic Acid; D002969:Clavulanic Acids / Q000494:pharmacology*; D004357:Drug Synergism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology*; D013982:Ticarcillin / Q000494:pharmacology*
D002969:Clavulanic Acids; D010406:Penicillins; D019818:Clavulanic Acid; D013982:Ticarcillin; D002512:Cephalothin