Comparison of Culture-Based Methods for Identification of Colonization with Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus in the Context of Cocolonization

Abstract

Two screening methods to detect staphylococcal colonization in humans were compared. Direct plating to CHROMagar (BD Diagnostics) was compared to a broth preenrichment followed by plating to Baird-Parker agar. The broth-enrichment method was comparable to CHROMagar for methicillin-resistant Staphylococcus aureas (MRSA) detection, but the enrichment method was optimum for recovery of coagulase-positive Staphylococcus spp.

FIG 1

Protocols for the two culture-based methods (CHROMagar and broth enrichment) compared in this analysis. Additional incubation time (24 to 48 h) before reading of the inoculated agar media plates (CHROMagar or Baird-Parker) is not depicted but was comparable between the methods. For the broth-enrichment method, multiple colonies were selected from the blood agar plates based on distinct colony morphology, and these were subcultivated as needed before pure colony growth was inoculated onto Baird-Parker agar; this may result in an additional day or (rarely) days to complete the protocol.