In Vitro Activities of Cefminox against Anaerobic Bacteria Compared with Those of Nine Other Compounds

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FONTE

American Society for Microbiology

RESUMO

The agar dilution MIC method was used to test the activity of cefminox, a β-lactamase-stable cephamycin, compared with those of cefoxitin, cefotetan, moxalactam, ceftizoxime, cefotiam, cefamandole, cefoperazone, clindamycin, and metronidazole against 357 anaerobes. Overall, cefminox was the most active β-lactam, with an MIC at which 50% of isolates are inhibited (MIC50) of 1.0 μg/ml and an MIC90 of 16.0 μg/ml. Other β-lactams were less active, with respective MIC50s and MIC90s of 2.0 and 64.0 μg/ml for cefoxitin, 2.0 and 128.0 μg/ml for cefotetan, 2.0 and 64.0 μg/ml for moxalactam, 4.0 and >128.0 μg/ml for ceftizoxime, 16.0 and >128.0 μg/ml for cefotiam, 8.0 and >128.0 μg/ml for cefamandole, and 4.0 and 128.0 μg/ml for cefoperazone. The clindamycin MIC50 and MIC90 were 0.5 and 8.0 μg/ml, respectively, and the metronidazole MIC50 and MIC90 were 1.0 and 4.0 μg/ml, respectively. Cefminox was especially active against Bacteroides fragilis (MIC90, 2.0 μg/ml), Bacteroides thetaiotaomicron (MIC90, 4.0 μg/ml), fusobacteria (MIC90, 1.0 μg/ml), peptostreptococci (MIC90, 2.0 μg/ml), and clostridia, including Clostridium difficile (MIC90, 2.0 μg/ml). Time-kill studies performed with six representative anaerobic species revealed that at the MIC all compounds except ceftizoxime were bactericidal (99.9% killing) against all strains after 48 h. At 24 h, only cefminox and cefoxitin at 4× the MIC and cefoperazone at 8× the MIC were bactericidal against all strains. After 12 h, at the MIC all compounds except moxalactam, ceftizoxime, cefotiam, cefamandole, clindamycin, and metronidazole gave 90% killing of all strains. After 3 h, cefminox at 2× the MIC produced the most rapid effect, with 90% killing of all strains.

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