DEVELOPMENT OF BETA-LACTAMASE-MEDIATED RESISTANCE TO PENICILLIN IN MIDDLE-EAR ISOLATES OF MORAXELLA-CATARRHALIS IN FINNISH CHILDREN, 1978-1993

The frequency of beta-lactamase production was analyzed in a study of 1,452 strains of Moraxella catarrhalis and 2,738 strains of Haemophilu s influenzae isolated from middle-ear fluid of children <6 years of ag e at Tampere University Hospital in Tampere, Finland, between 1978 and 1993, In addition, 401 isolates of M. catarrhalis from similar sample s collected in different parts of Finland in 1988-1990 were tested for beta-lactamase production; minimal inhibitory concentrations of ampic illin, cefaclor, cephalothin, erythromycin, tetracycline, and trimetho prim-sulfamethoxazole for these strains were determined, These data we re compared with figures for the annual consumption of beta-lactam ant imicrobials in the community in 1978-1993, A bimodal increase in the p roportion of strains of M. catarrhalis producing beta-lactamase was de tected: from 0 to 60% in 1978-1983 and from 60% to 80% in 1988-1990, C oncurrently with the second increase, the consumption of cephalosporin s increased substantially in the community. The frequency of beta-lact amase-producing strains of H. influenzae did not increase between 1978 and 1993.