PATHOGENS ISOLATED DURING TREATMENT FAILURES IN OTITIS

Objectives. A prospective study in the Paris region to evaluate the cl inical and bacteriologic epidemiology of acute otitis media in infants in whom oral antibiotic therapy resulted in clinical failure. Methods . The study included 186 children with a mean age of 17.5 +/- 13.1 mon ths. Two-thirds of them attended a day-care center and 40.8% had a his tory of recurrent otitis media. The most frequently prescribed prior a ntibiotics were amoxicillin-clavulanic acid (43% of cases), an oral th ird generation cephalosporin (22.6%), erythromycin-sulfisoxazole (11.8 %) and a first generation cephalosporin (10.2%). The average duration of antibiotic therapy was 6.9 +/- 2.65 days. Specimens for bacterial c ultures included 188 samples of middle ear fluid obtained by tympanoce ntesis and 37 collected from otorrhea fluid. Results. One hundred fort y-one samples (62.7%) from 126 children yielded 170 bacterial isolates . In 60 children (32.3%) the culture of the ear pus was sterile. Among the 170 bacterial isolates: 67 (39.4%) were Streptococcus pneumoniae (59 patients), of which 77.6% had reduced susceptibility to penicillin (PRSP with penicillin MIC greater than or equal to 0.125 mg/l); 61 (3 5.9%) were Haemophilus influenzae (56 patients) of which 49.2% were be ta-lactamase producers; and 8 were Moraxella catarrhalis (8 patients), of which 87.5% were beta-lactamase producers. Thirty-six patients wer e infected by S. pneumoniae with penicillin MIC greater than or equal to 1 mg/l. In our study attending day-care center (P = 0.04), temperat ure >38 degrees C with signs of otalgia (P = 0.02), age <2 years (P = 0.048) and prior antibiotic treatment with erythromycin-sulfisoxazole (P = 0.006) were independently predictive risk factors for patients in fected with penicillin-resistant S. pneumoniae. Pneumococcal serogroup s 23, 14 and 19 were predominant (25.4, 25.4 and 23.8%, respectively). Penicillin resistance was mainly associated with serogroups 23 and 14 . Conclusions. Penicillin-resistant S. pneumoniae isolates are frequen tly responsible for therapeutic failure in cases of acute otitis media in the Paris region.