Frequency and type distribution of pneumococcal strains in the Stockholm region with resistance or reduced susceptibility to antibiotics.

Of 191 consecutive clinical isolates of Streptococcus pneumoniae tested for antibiotic susceptibility with the agar dilution technique 87% were fully sensitive to all of 11 antimicrobial agents examined. 90% of the strains were inhibited by 0.016 micrograms/ml of benzylpenicillin, by 0.032 micrograms/ml of ampicillin, cefuroxime, erythromycin, clindamycin or rifampicin, by 0.13 micrograms/ml of cephalothin, oxacillin or doxycycline, by 4.0 micrograms/ml of chloramphenicol and by 8.0 micrograms/ml of cotrimoxazole. 18 strains exhibited a reduced susceptibility to one (11 strains) or more (7 strains) of erythromycin, doxycycline, chloramphenicol and cotrimoxazole. One of these strains also showed a reduced susceptibility to all 5 examined beta-lactam antibiotics, as did another 4 strains. Two of these 5 strains were isolated from small children recently adopted from 2 Asian countries. Cotrimoxazole-resistant strains were significantly more often isolated from children 1 yr of age or less than from older patients. All strains were fully sensitive to clindamycin and rifampicin. The existence of pneumococcal strains with resistance or reduced susceptibility to antibiotics commonly used for treatment of pneumococcal infections is important to bear in mind and necessitates antibiotic susceptibility testing of strains isolated from patients with severe infections.