Several recent reports have suggested MRSA may occasionally be transmitted in other community settings, particularly among preschool-age children, some of whom have attended daycare centers. Further studies are needed to determine if transmission of MRSA in community settings is becoming more common or is limited to a few geographic areas. Most strains of MRSA are multidrug resistant. Resistance to erythromycin and clindamycin are very common and many strains are resistant to gentamicin, tobramycin, and ciprofloxacin. In some geographic areas, resistance to co-trimazole and rifampin are also common.
Many strains are susceptible to minocycline.
Such strains have been confirmed to possess the mecA gene, and will grow on oxacillin-salt screening plates. The gold standard for determining if a strain of S. aureus is MRSA or not is to test the isolate for the presence of the mecA gene using polymerase chain reaction methods. However, this technique is not yet widely available in hospitals. Disk diffusion tests detect most MRSA but may not classify some heterogeneously resistant strains correctly. Occasionally, methicillin-susceptible strains of S. aureus may be misclassified as MRSA by certain automated susceptibility testing systems, which may lead to inappropriate management of affected patients.