Effect of new breakpoints proposed by Clinical and Laboratory Standards Institute in 2008 for evaluating penicillin resistance of Streptococcus pneumoniae in a Turkish University Hospital.

Clinical and Laboratory Standards Institute changed penicillin susceptibility breakpoints for Streptococcus pneumoniae in 2008. After reevaluation with new breakpoints, resistance rates decreased from 6.1% to 0.5% for nonmeningitis and increased from 6.6% to 33.3% for meningitis isolates in our hospital. This breakpoint modification is expected to reduce the inconsistency between susceptibility results and therapeutic outcomes; however, both the clinical microbiology laboratories and the clinicians should be aware of the change to interpret the susceptibility results.