When should healthcare workers be screened for methicillin-resistant Staphylococcus aureus?

The role of screening of healthcare workers (HCWs) in the control of methicillin-resistant Staphylococcus aureus (MRSA) is controversial. It is recommended in guidelines by expert groups in both North America and the United Kingdom, although the role of MRSA carriage by HCWs in outbreaks is not clearly defined. The present report describes the spread of a distinct strain of MRSA to patients by a single HCW on three separate occasions over 27 months. The isolates from this HCW and patient contacts were shown to be indistinguishable by antibiogram and repetitive extragenic palindromic polymerase chain reaction (REP/PCR); none were typeable by lytic phage-typing. Throat carriage of the MRSA probably recurred in this HCW, despite attempts to eradicate it on three occasions. Over the same period, nine other small clusters were seen in the Oxford Hospital Group, involving 66 patients and 22 HCWs colonized, or occasionally infected, with a variety of MRSA strains. In none of these instances could HCWs be implicated in the initiation of an outbreak. The advantages of a screening policy include the determination of the full extent of MRSA-colonization and work exclusion; the disadvantages include detection of transient nasal carriage, disruption of staff routine and stigmatization. Screening of HCWs can be a valuable tool in the control of MRSA outbreaks but it should be used selectively. This strategy remains an important part of a control programme.