Ceftazidime: in-vitro antibacterial activity and susceptibility to beta-lactamases compared with that of cefotaxime, moxalactam and other beta-lactam antibiotics.
The in-vitro antibacterial activity of ceftazidime was assessed against recent clinical isolates of common bacteria and also against reference strains that produced known beta-lactamases. The compound was active, though less so than cephaloridine against staphylococci and streptococci with MICs mostly 0.12-2 mg/l for streptococci and 8 mg/l for staphylococci, but enterococci (MICs > or =64 mg/l) and methicillin-resistant staphylococci (MICs 16-32 mg/l) were resistant. Penicillin-resistant pneumococci (MICs 2-4 mg/l) were much less sensitive than other pneumococci (MICs 0.12-0.25 mg/l). Ceftazidime was also active, but slightly less so than cefotaxime or moxalactam, against enterobacteria (MICs mostly 0.12-0.25 mg/l). Its activity was also inferior to that of cefotaxime against Neisseria gonorrhoeae (MICs mostly 0.03-0.06 mg/l) and Haemophilus influenzae (MICs mostly 0.06-0.25 mg/l). However it was about eightfold more active than cefotaxime or moxalactam against Pseudomonas aeruginosa (MICs mostly 1-4 mg/l), and it was also more active than these compounds against other pseudomonads. Ceftazidime was less active than cefoxitin against Bacteroides spp. (MICs mostly 16-64 mg/l for Bact. fragilis and 2-8 mg/l for other bacteroides) and less active than ampicillin or cefoxitin against other anaerobes. The compound was highly resistant to hydrolysis by most beta-lactamases including OXA-1 and the enzymes from Klebsiella 1082E and Proteus vulgaris PC37 which hydrolyse cefuroxime and cefotaxime. However, it was hydrolysed slowly by the enzyme from a highly ampicillin-resistant isolate of Bact. fragilis.
Department of Microbiology, St Thomas's Hospital Medical School, London, SE1 7EH, England.
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Phillips
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Warren
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Shannon
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King
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Hanslo
D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000201:enzymology; D001421:Bacteria, Anaerobic / Q000187:drug effects; D001424:Bacterial Infections / Q000382:microbiology; D002439:Cefotaxime / Q000378:metabolism / Q000494:pharmacology*; D002442:Ceftazidime / Q000378:metabolism / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D006088:Gram-Negative Aerobic Bacteria / Q000187:drug effects; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D009070:Moxalactam / Q000378:metabolism / Q000494:pharmacology*; D013210:Staphylococcus / Q000187:drug effects; D001618:beta-Lactamases / Q000378:metabolism*; D047090:beta-Lactams / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D002442:Ceftazidime; D001618:beta-Lactamases; D002439:Cefotaxime; D009070:Moxalactam