Susceptibility of Streptococcus pneumoniae to penicillin in the state of Minas Gerais, Brazil from 1997-2004.

We monitored the susceptibility to penicillin of invasive strains of Streptococcus pneumoniae in two reference laboratories; 502 positive cultures from patients with an active invasive infectious process were analyzed. Streptococcus pneumoniae was identified through conventional procedures, and the oxacillin disc diffusion method was used to check for penicillin susceptibility. Statistical analysis included calculations of the frequency distribution, with 95% confidence intervals (CI), as well as chi-square tests and chi-square for linear trend for temporal analysis of susceptibility.