Abstract
The in vitro activity of SCE-2787, 7-[(Z)-2-(5-amino-1,2,4-thiadiazol-3- yl)-2-methoxyiminoacetamido]-3-(1-imidazo[1,2-b]pyridazinium)methy l-3- cephem-4-carboxylate, was compared with those of ceftazidime, ceftriaxone, and imipenem against recent clinical isolates. SCE-2787 inhibited 50% of tested isolates of the family Enterobacteriaceae at < or = 0.25 micrograms/ml. SCE-2787 was equally active as or more active than ceftazidime and ceftriaxone against members of the Enterobacteriaceae, with the exception of Proteus vulgaris. The MIC of SCE-2787 at which 90% of the isolates of Pseudomonas aeruginosa were inhibited was 2 micrograms/ml, two- to fourfold lower than those of imipenem and ceftazidime, respectively. SCE-2787, like ceftazidime and imipenem, did not inhibit the majority of strains of Pseudomonas cepacia and Xanthomonas maltophilia. SCE-2787 inhibited beta-hemolytic streptococci at < or = 0.12 micrograms/ml, but it did not inhibit Enterococcus faecalis, Listeria monocytogenes, or the anaerobic species tested. Methicillin-resistant staphylococci required SCE-2787 MICs of > or = 16 micrograms/ml, whereas methicillin-susceptible staphylococci were inhibited by 2 micrograms/ml. No difference between the MICs and MBCs was noted, except for P. aeruginosa, for which there was a fourfold difference. SCE-2787 was active over a pH range of 6 to 8. The inoculum size of 10(5) to 10(7) CFU caused only a twofold change in the MIC for Escherichia coli and Staphylococcus aureus but a 4- to 16-fold change in Enterobacter cloacae and P. aeruginosa. beta-Lactamases from Bush groups 1, 2a, and 2b did not hydrolyze SCE-2787. There was significant hydrolysis of SCE-2787 by the beta-lactamases designated 2b', i.e., TEM-3, TEM-5, TEM-7, and TEM-9, and by the group 2d beta-lactamases. SCE-2787 had poor affinity for group 1 and group 2b enzymes and constitutively produced chromosomal beta-lactamases such as P-99 of Enterobacter cloacae and plasmid-mediated TEM-1 of E. coli. SCE-2787 has in vitro activity comparable to that of current parenteral cephalosporin and is more active against P. aeruginosa and S. aureus.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bush K. Characterization of beta-lactamases. Antimicrob Agents Chemother. 1989 Mar;33(3):259–263. doi: 10.1128/aac.33.3.259. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Iwahi T., Okonogi K., Yamazaki T., Shiki S., Kondo M., Miyake A., Imada A. In vitro and in vivo activities of SCE-2787, a new parenteral cephalosporin with a broad antibacterial spectrum. Antimicrob Agents Chemother. 1992 Jul;36(7):1358–1366. doi: 10.1128/aac.36.7.1358. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jorgensen J. H., Redding J. S., Maher L. A., Howell A. W. Improved medium for antimicrobial susceptibility testing of Haemophilus influenzae. J Clin Microbiol. 1987 Nov;25(11):2105–2113. doi: 10.1128/jcm.25.11.2105-2113.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nakao M., Noji Y., Iwahi T., Yamazaki T. Antibacterial properties of SCE-2787, a new cephem antibiotic. J Antimicrob Chemother. 1992 May;29(5):509–518. doi: 10.1093/jac/29.5.509. [DOI] [PubMed] [Google Scholar]