THE ANTIBACTERIAL ACTIVITY OF NEW CEPHEM ANTIBIOTICS AGAINST CLINICAL ISOLATES

A COMPARISON OF THE ANTIBACTERIAL ACTIVITY OF CEFOTAXIME WITH 6 OTHER ANTIBIOTICS

Abstract

During the period from May through July 1981, a comparative study was carried out on the antibacterial activities of cefotaxime (CTX) and ceftizoxime (CZX), cefoperazone (CPZ), latamoxef (LMOX), cefotiam (CTM), cefmetazole (CMZ) and cefazolin (CEZ). CTX and these other cephem antibiotics were tested against fresh clinical isolates which had been obtained from clinical materials by the laboratories of 14 participating medical institutions.
1. The clinical isolates were obtained from various clinical materials in the following decreasing order; urine, sputum and pus/discharge; 85.7% of the isolates came from these materials.
2. Concerning the sources of each species of clinical isolates, it was found that P. aeruginosa was isolated from the greatest number-9-of different clinical materials. This was followed by E. coli and E. cloacae, each isolated from 8 different clinical materials, and C. freundii and E. aerogenes, each found in 7 different clinical materials.
3. In relation to S. pyogenes, S. agalactiae and S. pneumoniae, CTX showed the best antibacterial activity; the second most potent antibiotic was CZX. CMZ and LMOX were found to show relatively high MIC values for those species. Against S. aureus, CEZ showed the best antibacterial activity, but 3 resistant strains had MICs of>100 μg/ml.
4. With regard to Gram-negative bacteria, CTX and CZX showed the best antibacterial activities for all of the species, except for P. aeruginosa. These were followed, in order, by LMOX and CPZ. Compared with these 4 antibiotics, CTM, CMZ and CEZ were found to have inferior antibacterial activities against these bacteria. In relation to P. aeruginosa, the peak of the MIC distribution for CPZ was 6.25μg/ml, and this was the best antibacterial activity detected with the various antibiotics tested. This was followed by CTX (25μg/ml) LMOX (25μg/ml) and CZX (50μg/ml). CTM had an MIC of 100μg/ml for 1 strain, and MICs of>100μg/ml for all of the other strains of P. aeruginosa, indicating them to be resistant to this antibiotic. All of the strains were resistant to CMZ and CEZ, showing MICs of>100μg/ml.
5. For each of the tested antibiotics, no correlation was found between the MIC and the serogroup for either P. aeruginosa or S. marcescens.