Improved detection of methicillin-resistant Staphylococcus aureus using phenyl mannitol broth containing aztreonam and ceftizoxime.

We tested a phenyl mannitol broth containing ceftizoxime and aztreonam (PHMB(+)) for detection of methicillin-resistant Staphylococcus aureus (MRSA) with reference MRSA strains and, subsequently, with clinical samples (n = 1,098). All reference MRSA strains induced color change in PHMB(+) after 24 to 72 h of incubation. In a clinical setting, 40 MRSA strains were detected with PHMB(+), compared with only 23 detected with a routine method. Thus, this selective broth significantly (P < 0.001) improved the rate of MRSA detection.