Fig 1.

Genomic targets used by different generations of MRSA screening tests and expected cases of false-positive MRSA detections. Three generations of MRSA screening tests have been successively developed to improve the specificity of MRSA detection by including new combinations of genomic targets (circled). However, each generation of MRSA screening tests still suffers from specificity issues with false detection of MRSA in the case of MSSA and MRCoNS cocolonization (first generation), presence of mecA dropout MSSA (second generation), and mecA dropout MSSA and MRCoNS cocolonization (third generation). MSSA, methicillin-susceptible S. aureus; MRSA, methicillin-resistant S. aureus; CoNS, coagulase-negative staphylococci.