[Antimicrobial activities of clarithromycin against recent obtained clinical isolates]

In order to evaluate antimicrobial activities of clarithromycin (CAM), minimum inhibitory concentrations (MICs) of CAM and control drugs were determined against clinical isolates that were obtained from outpatients in 1994 and 1996. The results are summarized as follows; 1. It was not showed that CAM-resistant strains were increasing among Staphylococcus spp., beta-streptococci, Moraxella subgenus Branhamella catarrhalis, Haemophilus influenzae, Bordetella pertussis, Campylobacter jejuni subsp. jejuni, Chlamydia trachomatis and Mycoplasma pneumoniae. It appeared that resistances to CAM and macrolides (MLs) were increasing among Streptococcus pneumoniae and Peptostreptococcus spp. 2. The drug susceptibility patterns to MLs were similar and detection frequencies of induced resistant strains that were resistant to only 14-membered ring MLs including CAM and constitutive resistant strains that were resistant to 14 and 16-membered ring MLs were high among Streptococcus pneumoniae and Peptostreptococcus spp. It appears that MLs-resistance systems are linked to each other, and that this was a cause of increasing MLs-resistance among these bacterial species. 3. Notwithstanding of antibiotic resistance problems, CAM is still useful since it maintains strong antimicrobial activities against M. (B.) catarrhalis, B. pertussis, C. jejuni subsp. jejuni, C. trachomatis and M. pneumoniae, and it controls arginate producing abilities of mucoide strains of Pseudomonas aeruginosa.