Comparison of five usual techniques for detection of methicillin-resistant Staphylococcus aureus

The detection of methicillin-resistant Staphylococcus aureus in an usual and daily test in a microbiology laboratory. But its interpretation isn't easy because the resistance expression in vitro is so variable. The authors compare five methods about 100 clinical isolated strains. The results are: disk diffusion method using oxacillin 5 microg, on a NaCl 5% Mueller Hinton agar, 100 ml presentation (biorad): specificity 91%; disk diffusion method using oxacillin 5 microg, on a NaCl 5% Mueller Hinton agar, ready to use plate (AES): specificity 95%; the Oxascreen agar (BD): specificity 96%; the oxacillin cupule of ATB STAPH strip (ATB expression bioMerieux system) NaCl 2% semi solid Mueller Hinton agar medium: specificity 100% and disk diffusion method using cefoxitin 30 microg, on a Mueller Hinton agar plate (bioMerieux): specificity 100%. Therefore the cefoxitin disk diffusion method is very interesting to make better the difference between methicillin-resistant and methicillin-sensible S. aureus, in association with the ATB STAPH strip.