ANTIMICROBIAL RESISTANCE IN HAEMOPHILUS-INFLUENZAE ISOLATED FROM BLOOD, CEREBROSPINAL-FLUID, MIDDLE-EAR FLUID AND THROAT SAMPLES OF CHILDREN - A NATIONWIDE STUDY IN FINLAND IN 1988-1990

A nation-wide survey of the prevalence of antimicrobial resistance in Haemophilus influenzae was conducted on isolates collected in 1988-90 from middle ear fluid (MEF), blood, or cerebrospinal fluid (CSF) in in fected children or throat samples of healthy children. Altogether 885 strains were examined regarding capsular type b, beta-lactamase produc tion and the minimal inhibitory concentration (MIC) of ampicillin, cef aclor, erythromycin, tetracycline, chloramphenicol, trimethoprim and t rimethoprim-sulfamethoxazole for these strains was determined by the a gar dilution method. 99% (578/585) of MEP isolates, 93% (112/121) of t hroat isolates, but only 6% (10/179) of blood/CSF isolates were not of type b (Hib). The rate of beta-lactamase production was 11.4% among H ib strains, 8.0% among non-type b MEF isolates, and 4.5% among non-typ e b throat isolates. No increase in the prevalence of beta-lactamase p roduction in H. influenzae has taken place in Finland since the early 1980s. Resistance to ampicillin among strains that lacked beta-lactama se activity was rare (0.2%). Of the non-type b MEF and throat isolates , 5.9% and 2.7%, respectively, were resistant to trimethoprim and 3.6% and 2.7%, respectively, to trimethoprim-sulfamethoxazole. Resistance to other drugs was rare (< 2%) in all isolate groups.