Prevalence and emerging resistance of Moraxella catarrhalis in lower respiratory tract infections in Karachi

Objective: To determine the prevalence of Moraxella catarrhalis in sputum cultures from patients with lower respiratory tract infection and their antimicrobial sensitivity profiles. Methods: The study comprised sputum specimens of 776 patients at various branches of Dr Essa s Diagnostic Lab, Karachi. The specimens were cultured on blood, chocolate, and eosin methylene blue agars between October 2010 and October 2011. The isolates were identified by conventional methods and anti-biograms were determined by the Kirby-Bauer Agar Disc Diffusion Method. Results: Moraxella catarrhalis was isolated from 39 (5.02%) sputa of which 18 (46.15%) belonged to males. The bimodal age prevalence was 238 (30.7%) in age group 20-29 years, and 180 (23.1%) in 70 years and above. Amoxicillin/clavulanate, cefotaxime, and ceftriaxone were most effective (100%). Very high resistance was seen with amikacin (92.3%), cefixime (92.3%), fosfomycin (84.6%), cefuroxime (84.6%), erythromycin and amoxicillin (76.9%), cotrimoxazole (90%) and doxycycline (76.9%). Conclusions: The incidence of Moraxella catarrhalis in sputum encourages routine culture and sensitivity of sputa from patients suffering from lower respiratory tract infection, especially the elderly and immunocompromised, for tailored drug prescription.