Minimum inhibitory concentration (MIC) analysis and susceptibility testing of MRSA

The widespread occurrence of methicillin-resistant Staphylococcus aureus (MRSA) or oxacillin-resistant MRSA is a major cause of concern worldwide. Although mainly located in hospital environments, these microorganisms have been reported to have the capacity to cause infections in the community. Resistance to methicillin implies resistance to all beta-lactam antibiotics and, furthermore, MRSA isolates normally harbor resistance to other families of antibiotics such as co-trimoxazole and aminoglycosides. Prompt and accurate detection of MRSA isolates is therefore extremely important in clinical microbiology laboratories. In this chapter, we review the most common methods of susceptibility testing for MRSA.