Changes in Antimicrobial Susceptibility to Moraxella catarrhalis over a Ten-Year Period

Abstract

AbstractMoraxella catarrhalis is an important organism causing respiratory infections. There have been several clinical failures to treat this infection using β-lactam antibiotics due to the wide prevalence of β-lactamase-producing strains. To determine trends in antibiotic susceptibility and suitable antibiotics for treatment, we determined the MICs of a panel of antibiotics againstM. catarrhalis, which were isolated from the sputum of patients with respiratory infections. These strains were randomly selected from stock isolates from 1984 to 1985 and from 1993 to 1994. It was found that over the 10-year period, the MIC90 increased against the β-lactam antibiotics. Satisfactory susceptibility was found with amoxicillin-clavulanic acid, third generation cephalosporins, carbapenems, tetracycline, erythromycin, aminoglycoside and new quinolones. High levels of β-lactamase-producing strains were found in both periods.