Effects of temperature on the detection of methicillin resistance in Staphylococcus aureus using cefoxitin disc diffusion testing with Iso-Sensitest agar
2009 (English)In: Journal of Antimicrobial Chemotherapy, ISSN 0305-7453, E-ISSN 1460-2091, Vol. 63, no 4, 699-703 p.Article in journal (Refereed) Published
Cefoxitin is today the substance of choice for the phenotypic detection of methicillin-resistant Staphylococcus aureus (MRSA). We investigated the influence of incubation temperature in the standard range, i.e. 35-37 degrees C, and time, i.e. 18-20 h, versus a full 24 h. Cefoxitin disc testing was examined at incubation temperatures of 35 and 36 degrees C and times of 18-20 and 24 h, respectively, for 94 mecA-negative and 49 mecA-positive S. aureus on Iso-Sensitest agar using a semi-confluent inoculum. Cefoxitin inhibition zones on Iso-Sensitest agar were larger at temperatures above 35 degrees C; two isolates (4%, 95% confidence interval=0.5-14%) incubated at 36 degrees C were falsely categorized as susceptible to methicillin. Incubation time across 18-24 h did not impact results. Detection of methicillin resistance in S. aureus using the cefoxitin disc method with a semi-confluent inoculum on Iso-Sensitest agar is influenced by incubation temperature, and the temperature should not exceed 35 degrees C for the reliable detection of MRSA.
Place, publisher, year, edition, pages
2009. Vol. 63, no 4, 699-703 p.
susceptibility testing, MRSA, S, aureus
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-129868DOI: 10.1093/jac/dkp019ISI: 000264191100011OAI: oai:DiVA.org:uu-129868DiVA: diva2:345534