The ability of participant laboratories to detect penicillin-resistant Pneumococci. A report from the microbiology portion of the College of American Pathologists (CAP) surveys.

To assess the ability of clinical laboratories to identify penicillin-resistant Streptococcus pneumoniae, a challenge sample was distributed to CAP Special Bacteriology surveys participants in 1981. Their performance was excellent (greater than 99%) for organism identification, but less than 15% of surveys subscribers that use the standardized disk diffusion test detected penicillin resistance. The recommendations of the NCCLS M2-A2S for 1-microgram oxacillin disk screening are discussed. The screening and dilution tests for detecting drug resistant S. pneumoniae seem to be accurate and the use of other disks, such as methicillin and nafcillin, also appear efficacious. Due to the clinical frequency of serious pneumococcal disease, all microbiology laboratories should be applying these screening procedures to appropriate patient isolates.