Antibiotic susceptibility of three major respiratory pathogens

Abstract

The aim of the study is to determine the antibiotic susceptibility of Moraxella catarrhalis, Streptococcus pneumoniae and Haemophilus influenzae to commonly used antibiotics and newer fluoroquinolones, extended-spectrum cephalosporins and macrolide. A total of 33 M catarrhalis, 201 H influenzae and 148 S. pneumoniae mains isolated from clinical specimens were subjected to antibiotic susceptibility testing by determination of minimum inhibitory concentration (MIC). MIC of antibiotics was determined using agar dilution method as outlined by NCCLS. S. pneumoniae resistant to penicillin was seen in 9.6% of isolates; susceptibility of M. catarrhalis to ampicillin and tetracycline was 21% and 97% respectively. The majority of the H. influenzae (91%) was still susceptible to chloramphenicol. Trovafloxacin was the most effective antibiotic against the 3 organisms tested, as all isolates tested were susceptible. Ciprofloxacin and cefepime were equally active against M. catarrhalis. Cefepime was more effective than fluoroquinolones against S. pneumoniae. Of the two fluoroquinolones tested, resistance to ciprofloxacin has emerged in Malaysian S. pneumoniae isolates.