Summary

The antimicrobial susceptibility of all 555 viable invasive isolates of S. pneumoniae referred to ESR in 2007 was tested. 22.3% (124) were penicillin nonsusceptible (MIC ≥0.12 mg/L): 6.3% (35) resistant (MIC ≥2 mg/L) and 16.0% (89) intermediate (MIC 0.12-1 mg/L). These interpretations are based on the CLSI standards current in 2007. The CLSI penicillin interpretive standards for S. pneumoniae were amended in January 2008. While there has been considerable variation in the prevalence of penicillin resistance during the last 10 years, there was no significant difference (P ≤0.05) in the rate of resistance in 1998 (7.2%) and that in 2007 (6.3%) (Figure 1). Penicillin nonsusceptibility was constant over most of the last 10 years, but there was a significant increase between 2006 and 2007.