Prevalence of Moraxella catarrhalis colonization in asymptomatic carriers under six years of age

Objective. To determine the prevalence of upper respiratory tract colonizat ion by Moraxella catarrhalis in children under six years of age. Material a nd methods. A survey was conducted between January and December 1998 in Mex ico City, among children aged 2 months to 5 years, selected through cluster sampling. Pharyngeal samples were taken for M. catarrhalis identification. The minimal inhibitory concentration to different antibiotics was obtained and betalactamases were determined by the iodometric test. Statistical ana lysis consisted of frequency distributions, odds ratios, 95% confidence int ervals, and Mantel-Haenszel chi (2). Statistical significance was set at p< 0.05. Results. After excluding 37 children, the study population was 604 ch ildren from Mexico City; M. catarrhalis was present in 130 pharyngeal speci mens (22.9%). Most of the strains were positive for beta-lactamase producti on (75.4%). Eighty percent of the strains was resistant to penicillin and 7 0% to ampicillin and amoxicillin. None were resistant to cefotaxime, imipen em, meropenem and erythromycin. Conclusions. Prevalence of M, catarrhalis u pper respiratory tract colonization is similar to that of other respiratory pathogens. These findings warrant future research on the role of M. catarr halis as an etiologic agent in acute and chronic respiratory infections in Mexico. The English version of this paper is available at: http://www.insp. mx/salud/index.html.