Beta-lactamase production and bacterial tolerance in recurrent acute otitis media.

Different reasons for treatment failure or relapse of acute otitis media (AOM) have been suggested. In this study 38 children (8 treatment failures, 13 relapses of AOM within one month and 17 with a new AOM) were compared to 25 matching healthy children, regarding beta-lactamase producing bacteria and tolerance to penicillin V and ampicillin. Branhamella catarrhalis was the most common bacteria found in the nasopharynx and was isolated in 60% of children with AOM and in 48% of the control group. Fifty-two percent of the children classified as treatment failure or relapse of AOM had aerobic beta-lactamase producing bacteria in NPH. No bacteria tolerant to penicillin or ampicillin were found. Thus, beta-lactamase-producing bacteria seem to play a decisive role in treatment failure and relapse of AOM. On the other hand, tolerance to penicillin V or ampicillin does not seem to have any impact on healing of AOM.