Routine screening of women having caesarean section for MRSA: Ritual or rational?

Meticillin-resistant Staphylococcus aureus (also known as methicillin-resistant Staphylococcus aureus or MRSA) is a growing problem throughout the world, and although originally associated with hospitals and other healthcare facilities, it also has occured more recently in the community. Although transmission of hospital-associated MRSA (HA-MRSA) in the community has been documented many times, these community strains (CA-MRSA) are distinct from their healthcare-associated equivalents, being genotypically different and consequently having different resistance profiles and pathogenic sequelae; one particularly important difference being that CA-MRSA has historically been susceptible to ciprofloxacin. Thus any discussion of MRSA transmission needs to take account of two different threats: those of HA- and CA-MRSA.

There have been a number of responses to the threat posed by MRSA, including an emphasis on hospital cleanliness and hygiene, reducing the use of antimicrobials that produce a selective environment for the development and spread of resistance, and the screening of people being admitted to hospital to identify those carrying MRSA so that they can be isolated and treated, if necessary. While MRSA has historically been seen as predominantly a hospital organism, the discovery of distinct CA-MRSA organisms complicated matters greatly, because the risk factors for carriage of these strains are very different. HA-MRSA usually affects patients who are in healthcare or institutional settings or those who have been in hospital recently, whereas CA-MRSA is often associated with younger and healthier people; transmission of CA-MRSA has, for example, been associated with activities that result in skin-to-skin contact such as contact sports (Cohen, 2007). Consequently, while previous hospital admission is a major risk factor for HA-MRSA, it is less significant for CA-MRSA, and MRSA screening programmes that focus on this and other HA-MRSA risk factors such as older age and admission to high-risk specialities may fail to identify CA-MRSA strains.