- Susceptibility to antibiotics of 199 isolates of Streptococcus pneumoniae from blood and cerebrospinal fluid of children hospitalized during 1987-1993 was tested. Of 119 isolates, 18% were resistant to penicillin. The prevalence in 1992-93 was double that in 1987-89. The increase in minimal inhibitory concentrations (MIC) of penicillin was associated with an increase in MIC of other beta-lactams. There was also resistance to other antibiotics: trimethoprim-sulfamethoxazole, erythromycin and chloramphenicol. Most of the resistant isolates belonged to serogroups 6, 14, 19 and 23. When planning vaccine policies, resistant types should be taken into consideration.