Comparative susceptibility patterns of common clinical isolates to cefoperazone: 1981 to 1987

It has been postulated that the widespread use of broad-spectrum cephalosporins might lead to increased bacterial resistance to such agents. To determine if such increased resistance to cefoperazone might be detectable, the susceptibility patterns of common clinical isolates to cefoperazone were examined from the Pathology Laboratories at Baptist Medical Center, Jacksonville, Florida, from 1981, prior to approval by the Food and Drug Administration, to the present. Gram-negative aerobic and facultative anaerobic organisms, staphylococci, and members of the Bacteroides fragilis group were included in the analysis. The data obtained were compared with results of similar published studies nationwide. No significant decrease in susceptibility to cefoperazone was detected for any gram-negative species examined. A steady increase in the percentage of staphylococci (both coagulase positive and especially coagulase negative) resistant to cefoperazone was demonstrable at this institution. This was a direct function of the concomitant rise in the percentages of staphylococci resistant to methicillin observed over the testing interval. Anaerobic susceptibility patterns of the members of the B. fragilis group were also relatively constant during this period of time. The concentrations of antibiotic inhibiting 50 percent (MIC50) and 90 percent (MIC90) of B. fragilis isolates as determined by an agar dilution technique were 16 micrograms/ml and 64 micrograms/ml, respectively, both in 1981 and in 1987. No change in the national susceptibility patterns of common bacterial isolates to cefoperazone was demonstrable in the five-year period during which the antibiotic has been available for clinical use.