Clinical isolates and nasopharyngeal carriage of antibiotic-resistant Streptococcus pneumoniae in Hospital for Infectious Diseases, Sofia, Bulgaria, 1991-1993.

The antimicrobial resistance of Streptococcus pneumoniae was surveyed in 1991-1993 at the Hospital for Infectious Diseases in Sofia, Bulgaria. Pneumococcal isolates were collected from routine clinical specimens and from nasopharyngeal secretions of inpatient carriers. The incidence of penicillin-resistant S. pneumoniae (PRSP) was 24.3% among clinical samples and nasopharyngeal carriage of PRSP was as high as 40% among children. Penicillin-resistant strains were more frequently resistant to non-beta-lactam antibiotics than were penicillin-sensitive strains. More than half of the PRSP strains were multiply resistant. On the basis of MIC values of ampicillin, it was established that ampicillin was not superior to penicillin. The MICs of five cephalosporins were found to increase in parallel with the MICs of penicillin G. Some of the pneumococcal strains that were highly penicillin-resistant were also resistant to cefotaxime/ceftriaxone (MIC = 1-4 micrograms/ml), but the number of strains was small. On the basis of MIC values of cefotaxime and ceftriaxone for strains from cerebrospinal fluid, both antibiotics may be suitable alternatives for treating meningitis due to strains with resistance to penicillin.