Cepheid Xpert MRSA cycle threshold in discordant colonization results and as a quantitative measure of nasal colonization burden.

We analyzed the cycle threshold (C(T)) of PCR surveillance MRSA swabs obtained from veterans. Lower C(T) on admission was associated with a positive culture from nasal swabs at discharge. Compared to PCR, direct plating of nasal swabs performed poorly, especially for patients with an elevated C(T). The C(T) is strongly correlated with quantitative nasal cultures. Clinical and infection control applications of the C(T) have yet to be defined and warrant further evaluation.