In-vitro activity of HMR 3647 against Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and β-haemolytic streptococci

• Published in: Journal of antimicrobial chemotherapy Vol. 44; no. 4; pp. 445 - 453
• Main Authors: WOOTTON, M, BOWKER, K. E, JANOWSKA, A, HOLT, H. A, MACGOWAN, A. P
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.10.1999
• Subjects: Anti-Bacterial Agents - pharmacology; Antibacterial agents; Antibiotics. Antiinfectious agents. Antiparasitic agents; Biological and medical sciences; Drug Resistance, Microbial; Haemophilus influenzae; Haemophilus influenzae - drug effects; Humans; Ketolides; Macrolides; Medical sciences; Microbial Sensitivity Tests; Moraxella (Branhamella) catarrhalis - drug effects; Pharmacology. Drug treatments; Streptococcus - drug effects; Streptococcus pneumoniae; Streptococcus pneumoniae - drug effects; Respiratory disease; In vitro; Biological activity; Haemophilus influenzae; Streptococcus pneumoniae; Infection; Pasteurellaceae; Streptococcaceae; Antibiotic; Minimum inhibitory concentration; Bacteriosis; Bacteria; Micrococcales; Antibacterial agent
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/44.4.445

The in-vitro activity of HMR 3647 and seven comparators (azithromycin, clarithromycin, erythromycin A, roxithromycin, penicillin G, ciprofloxacin and levofloxacin) were tested against 207 Streptococcus pneumoniae and 200 beta-haemolytic streptococci. Ten comparators (azithromycin, clarithromycin, erythromycin A, roxithromycin, ampicillin, co-amoxiclav, cefuroxime, cefotaxime, ciprofloxacin and levofloxacin) were tested against 143 Haemophilus influenzae and 58 Moraxella catarrhalis. The MIC50 of HMR 3647 for S. pneumoniae was < or =0.008 mg/L, less than that for the macrolides or quinolones tested. Pneumococci with an erythromycin A MIC of 0.06 mg/L (n = 23) had an MIC50 of HMR 3647 < or =0.008 mg/L, whereas isolates with an erythromycin A MIC > or =1 mg/L (n = 34) had an MIC50 of HMR 3647 of 0.03 mg/L, a four-fold increase. In contrast, the difference in macrolide MIC50s for the two groups was > or =64-fold. The MIC50s foro beta-haemolytic streptococci, classified by Lancefield group, were in the range 0.015 to 0.06 mg/L for HMR 3647. H. influenzae were categorized into three groups according to cefuroxime MIC: <1 mg/L (n = 72); 2-4 mg/L (n = 29); and >4 mg/L (n = 42). The MIC50 of HMR 3647 increased two-fold with increasing cefuroxime MICs; beta-lactam MICs increased much more markedly. The MIC50 of HMR 3647 for M. catarrhalis was 0.03 mg/L. HMR 3647 has good activity against respiratory tract pathogens but in-vitro susceptibility is affected by erythromycin A susceptibility in S. pneumoniae and beta-haemolytic streptococci.