Cefoxitin resistance as a surrogate marker for the detection of methicillin-resistant Staphylococcus aureus.
OBJECTIVE
To evaluate the usefulness of cefoxitin when used as a surrogate marker for the detection of methicillin resistance.


METHODS
Eight hundred and seventy-one strains of Staphylococcus aureus, collected from eight tertiary referral centres serving diverse socio-economic populations, were included in the study using NCCLS disc diffusion and the agar dilution methods.


RESULTS
Using cefoxitin and NCCLS criteria for disc diffusion, the sensitivity and specificity for recognizing methicillin resistance were both 100%. Similar results were obtained when the strains were tested by the agar dilution method. The cefoxitin MICs for methicillin-susceptible strains were < or = 4 mg/L.


CONCLUSIONS
Testing with cefoxitin as a surrogate marker for the detection of methicillin resistance was very accurate with both disc diffusion and agar dilution methods. Such testing clearly distinguished methicillin-resistant strains of S. aureus from methicillin-susceptible strains.
Fernandes
Clarence J
CJ
Department of Microbiology, Pacific Laboratory Medicine Services, Royal North Shore Hospital, St Leonards 2065, Australia.
Fernandes
Lorna A
LA
Collignon
Peter
P
D015415:Biomarkers; D002440:Cefoxitin / Q000494:pharmacology*; D018550:Cephalosporin Resistance; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D013211:Staphylococcus aureus / Q000187:drug effects*
D015415:Biomarkers; D002440:Cefoxitin