In vitro activities and targets of three cephem antibiotics against Haemophilus influenzae
| Autor: | E. A. Wiley, A L Smith, Donald O. Chaffin, T L Stull, P M Mendelman, L L Henritzy, K Lent |
|---|---|
| Rok vydání: | 1989 |
| Předmět: |
medicine.drug_class
Penicillin Resistance Antibiotics Cefotaxime Microbial Sensitivity Tests Biology Muramoylpentapeptide Carboxypeptidase medicine.disease_cause Cefpodoxime Haemophilus influenzae Microbiology Bacterial Proteins Cefixime medicine Penicillin-Binding Proteins Pharmacology (medical) Ceftibuten Antibacterial agent Pharmacology Cephem Antimicrobial Cephalosporins Culture Media Kinetics Infectious Diseases Phenotype Hexosyltransferases Peptidyl Transferases Ampicillin Carrier Proteins medicine.drug Research Article |
| Zdroj: | Antimicrobial agents and chemotherapy. 33(11) |
| ISSN: | 0066-4804 |
| Popis: | The antimicrobial activities of cefixime, cefpodoxime, and ceftibuten were determined with 18 ampicillin-susceptible (Amps), 13 ampicillin-resistant beta-lactamase-producing (AmprBLP), and 7 ampicillin-resistant non-beta-lactamase-producing (AmprNBLP) strains of Haemophilus influenzae. An effect of inoculum density on apparent MIC, the bactericidal activity of these agents, and the targets of the three cephems were determined. The MICs of cefixime, cefpodoxime, and ceftibuten for 90% of the Amps and AmprBLP isolates were 0.04, 0.08, and 0.08 microgram/ml, respectively. In contrast, the MICs for 90% of the AmprNBLP strains were 0.96, 1.92, and 7.68 micrograms/ml. No significant inoculum effect was observed for any group of strains comparing inocula of 10(3) and 10(5) CFU, whereas only the AmprNBLP isolates showed a marked effect at an inoculum of 10(6) CFU. Although bactericidal levels were achieved for the Amps and AmprBLP strains, tolerance to cefixime and ceftibuten was observed. The bactericidal activity for the AmprNBLP strains was limited, with cefixime showing the highest activity of the three cephems. Penicillin-binding proteins 2, 4, and 5 revealed high affinity, with 50% inhibitory concentration levels below the MIC for all three cephems, suggesting that these are important targets of these agents in H. influenzae. We conclude that the cephems are highly active in vitro against Amps and AmprBLP strains of H. influenzae, but less so against AmprNBLP isolates. |
| Databáze: | OpenAIRE |
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