Austrian national survey of prevalence of antimicrobial resistance among clinical isolates of Streptococcus pneumoniae 1994-96.

The antimicrobial susceptibilities of 1385 clinical isolates of Streptococcus pneumoniae obtained from 25 laboratories across Austria between December 1994 and January 1996 were tested. Minimal inhibitory concentration (MIC) values were determined in tests with penicillin, amoxycillin, amoxycillin/clavulanate, ceftriaxone, cefodizime, cefpirome, cefotaxime, cefpodoxime, cefadroxile, azithromycin, clarithromycin, josamycin and roxithromycin by the agar-dilution method. A total of 40 isolates (2.9%) demonstrated intermediate resistance (MIC 0.125-1 microg/ml) and 28 isolates (2.0%) had high-level resistance (MIC > or = 2 microg/ml) to penicillin. Excepting cefadroxil, with an MIC90 of 2 microg/ml, all other tested beta-lactams had MIC90s of 0.03-0.06 microg/ml. Penicillin-resistant strains were much more likely to be also resistant to the other beta-lactams. The macrolides proved to be very active compounds against pneumococci with MIC90s of 0.06 microg/ml (clarithromycin) and 0.25 microg/ml (all other macrolides). Regional differences within Austria with regard to antimicrobial resistance were not observed.