Frequency and Risk Factors of Moraxella catarrhalis Infection in Patients at Vali-Asr and Amirkabir Hospitals since August 2003 to March 2004

Background: Moraxella catarrhalis is Gram negative diplococci which is a member of Neisseriacae. It was considered as a harmless commensal of the upper respiratory tract. Since 1990 its pathogenecity was established and known as a common cause of respiratory infection, particularly otitis media, sinusitis and lower respiratory tract. The aim of this research was to determine the prevalence and risk factors of Moraxella catarrhalis infection. Materials and Methods: This study performed prospectively on 123 patients with lower respiratory infection, 42 patients with otitis media and 35 patients with sinusitis. Samples (sputum, middle ear fluid, and aspirate from sinuses) were cultured on microbiologic media. Moraxella catarrhalis was isolated from some of these samples and its identity was approved by catalase, superoxole, nitrate reduction, DNase, antibiogramm (disk diffusion) and nitrocefin test for β-lactamase. Findings: the bacterium was isolated from 17 cases (11 lower respiratory infection, 4 otitis media, 2 sinusitis).‏‏ There was no any relation between smoking and sex with the infection of Moraxella catarrhalis, but age (more than 50) and underlying diseases especially COPD was the risk factor for infection of Moraxella catarrhalis. Isolated bacteria were sensitive to ciprofloxacine, cefixime, and erythromycin and resistant to penecilline, amoxycilline, Co-trimoxazole, and vancomycine. Among the penecilline resistant bacteria, 93 percent produced β-lactamase. Conclusion: Moraxella catarrhalis is an important pathogen in respiratory tract especially elderly with underlying COPD. In addition, Moraxella catarrhalis may be the single cause of sinusitis and otitis media. The very high incidence of antimicrobial resistat strain in our area emphasizes the need for more epidemiological studies.