title: Assessment of the oxacillin disk screening test for determining penicillin resistance in Streptococcus pneumoniae.
abstract: The 1 microgram oxacillin disk diffusion screening test was performed on 1516 recent clinical isolates of Streptococcus pneumoniae obtained in a 1994-1995 U.S. surveillance study and the results compared to penicillin MICs determined using a standardized broth microdilution method. The oxacillin disk screening method failed to distinguish penicillin-resistant strains from those that were intermediately susceptible. Furthermore, a high percentage (11.1%) of penicillin-susceptible strains, for which MICs of penicillin were usually 0.06 or 0.03 microgram/ml, yielded zone diameters of < or = 19 mm with the oxacillin screen test and thus would have been falsely categorized as being resistant to penicillin.
authors.affiliation: Clinical Microbiology Laboratories, University of Massachusetts Medical Center, Worcester 01655, USA.
authors.forename: G V
authors.initials: GV
authors.lastname: Doern
authors.forename: A B
authors.initials: AB
authors.lastname: Brueggemann
authors.forename: G
authors.initials: G
authors.lastname: Pierce
mesh_terms: D008826:Microbial Sensitivity Tests / Q000379:methods*; D010068:Oxacillin / Q000494:pharmacology*; D010403:Penicillin Resistance; D010406:Penicillins / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D013296:Streptococcus pneumoniae / Q000187:drug effects*
chemical_list: D010406:Penicillins; D010068:Oxacillin