page_title: Methicillin-resistant Staphylococcus aureus
section_title: Diagnosis
hierarchical_section_title: Methicillin-resistant Staphylococcus aureus / Diagnosis
caption_attribution_description: A chromogenic MRSA selective media plate showing the change of colour i.e. bright pink as result of MRSA being present.
context_page_description: Methicillin-resistant Staphylococcus aureus refers to a group of Gram-positive bacteria that are genetically distinct from other strains of Staphylococcus aureus. MRSA is responsible for several difficult-to-treat infections in humans. MRSA is any strain of S. aureus that has developed, through horizontal gene transfer and natural selection, multiple drug resistance to beta-lactam antibiotics. Beta-lactam antibiotics are a broad-spectrum group that include some penams and cephems such as the cephalosporins. Strains unable to resist these antibiotics are classified as methicillin-susceptible S. aureus, or MSSA.
  MRSA is common in hospitals, prisons, and nursing homes, where people with open wounds, invasive devices such as catheters, and weakened immune systems are at greater risk of hospital-acquired infection. MRSA began as a hospital-acquired infection but has become community-acquired, as well as livestock-acquired. The terms HA-MRSA, CA-MRSA, and LA-MRSA reflect this.
context_section_description: Diagnostic microbiology laboratories and reference laboratories are key for identifying outbreaks of MRSA. Normally, a bacterium must be cultured from blood, urine, sputum, or other body-fluid samples, and in sufficient quantities to perform confirmatory tests early-on. Still, because no quick and easy method exists to diagnose MRSA, initial treatment of the infection is often based upon "strong suspicion" and techniques by the treating physician; these include quantitative PCR procedures, which are employed in clinical laboratories for quickly detecting and identifying MRSA strains.
  Another common laboratory test is a rapid latex agglutination test that detects the PBP2a protein. PBP2a is a variant penicillin-binding protein that imparts the ability of S. aureus to be resistant to oxacillin.
caption: A selective and differential chromogenic medium for the qualitative direct detection of MRSA
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