In vitro activity of ertapenem against selected respiratory pathogens

• Published in: Journal of antimicrobial chemotherapy Vol. 54; no. 5; pp. 944 - 951
• Main Authors: Marchese, A., Gualco, L., Schito, A. M., Debbia, E. A., Schito, G. C.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.11.2004; Oxford Publishing Limited (England)
• Subjects: Antibiotics. Antiinfectious agents. Antiparasitic agents; Bacteria - drug effects; bactericidal activity; beta-Lactams; Biological and medical sciences; carbapenems; Haemophilus influenzae; Humans; interactions; Klebsiella pneumoniae; Lactams - pharmacology; Medical sciences; Microbial Sensitivity Tests; Moraxella (Branhamella) catarrhalis - drug effects; Moraxella catarrhalis; Pharmacology. Drug treatments; Respiratory Tract Infections - microbiology; Staphylococcus aureus; Staphylococcus aureus - drug effects; Streptococcus pneumoniae; Streptococcus pneumoniae - drug effects; Streptococcus pyogenes; Streptococcus pyogenes - drug effects; time–kill; Respiratory tract; Carbapenem derivatives; Antibiotic; β-Lactams; Antibacterial agent; Ertapenem; In vitro; Biological activity
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkh445

Objectives: The in vitro activity of ertapenem was evaluated in comparison to 21 selected agents against a large collection of recently isolated respiratory tract pathogens including: 180 Streptococcus pneumoniae, 100 Streptococcus pyogenes, 70 Haemophilus influenzae, 70 Moraxella catarrhalis, 100 methicillin-susceptible Staphylococcus aureus and 30 Klebsiella pneumoniae. Additional in vitro tests (time–kill curves with ertapenem alone and in combination with four other agents) for S. pneumoniae were carried out. Methods: MIC determinations and time–kill curves were carried out following the procedures suggested by the NCCLS. Results: According to NCCLS susceptibility breakpoints, ertapenem was comparable to the most potent compounds tested for all pathogens studied. Ertapenem was 100% active against penicillin-susceptible and -intermediate S. pneumoniae and against 60% of penicillin-resistant strains. Time–kill tests at 4× MIC confirmed a pronounced bactericidal potency of ertapenem against these organisms. Interactions of ertapenem with several other agents against pneumococci resulted in clear synergic interactions (98.4%). Indifference was extremely rare and antagonism was not observed. All S. pyogenes strains tested were inhibited by ertapenem, irrespective of their macrolide resistance phenotypes. Ertapenem was also fully active against H. influenzae (100% susceptible) and M. catarrhalis (MIC90 0.015–0.03 mg/L) even when capable of synthesizing β-lactamases. Methicillin-susceptible S. aureus and K. pneumoniae, including extended-spectrum β-lactamase-producing strains, were 100% susceptible to ertapenem. Conclusions: Our results indicate that ertapenem has a suitable spectrum of activity against organisms encountered in community-acquired bacterial respiratory tract infections.