Screening specimens were homogenised in saline 0.9% w/v before either direct 
inoculation or following enrichment in broth on three chromogenic media 
(MRSA-ID, CHROMagar MRSA and MRSA Select) and ORSAB medium for the detection of 
methicillin-resistant Staphylococcus aureus (MRSA). In total, 102 of 466 
specimens yielded MRSA on at least one medium. After incubation for 16-18 h, the 
sensitivity was 51%, 59%, 47% and 65% on MRSA-ID, CHROMagar MRSA, ORSAB and MRSA 
Select, respectively, compared with 82%, 75%, 67% and 80%, respectively, after 
42 h, and 93%, 95%, 79% and not tested, respectively, following broth 
enrichment. There were significantly more MRSA colonies on MRSA-Select after 
16-18 h than on ORSAB or MRSA ID (p 0.001 and 0.0022, respectively), whereas 
there were more MRSA colonies after 42 h on MRSA-ID and MRSA-Select than on 
ORSAB (p 0.0004 and 0.012, respectively). The specificity of the media for 
identifying MRSA based on the colour of colonies after incubation for 16-18 h 
was 100%, 99%, 99% and 100%, respectively, compared with 98%, 97%, 98% and 98%, 
respectively, after 42 h, and 100%, 99%, 100% and not tested, respectively, 
following broth enrichment. The speed of detection (mean time to report a 
positive result) was 1.65, 1.72, 2.31 and 1.35 days, respectively. For each of 
the three media tested following enrichment, the use of an enrichment broth 
increased the detection rate of MRSA by 16-24%.