Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

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.

Original publication




Journal article


European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology

Publication Date





311 - 314


Clinical Microbiology Laboratories, University of Massachusetts Medical Center, Worcester 01655, USA.


Streptococcus pneumoniae, Penicillins, Oxacillin, Microbial Sensitivity Tests, Sensitivity and Specificity, Penicillin Resistance