OCCURRENCE OF PNEUMOCOCCI WITH RESISTANCE OR DECREASED SUSCEPTIBILITYTO PENICILLIN IN SOUTHEAST SWEDEN

The minimal inhibitory concentrations (MICs) of 14 beta-lactam and non -beta-lactam antibiotics were determined for all pneumococci with inte rmediate susceptibility (I), (n = 26) or resistance (R), (n = 15) to p enicillin G isolated at the Clinical Microbiology Laboratory, Universi ty Hospital, Linkoping, Sweden during 1994. These isolates accounted f or 3% of ail pneumococcal isolates. The results were compared with tho se of 26 penicillin-susceptible isolates. The MICs of all tested beta- lactam antibiotics increased with MICs of penicillin G. The least incr ease and the lowest MICs of these agents were recorded for cefotaxime and imipenem. 27% of I- and R-strains were multiple-resistant, most of ten to tetracycline, trimethoprim-sulfametoxazole, erythromycin, chlor amphenicol and clindamycin. All strains were susceptible to vancomycin and rifampicin. I-strains belonged to at least 5 different serotypes. However, 12 of the 15 R-strains were serotype 9 and 6 of these were r ecovered during contact tracing, indicating spread of a single clone w ithin day-care centres.