MRSA screening on a paediatric intensive care unit

The accuracies of chromogenic agar and the GeneXpert real-time PCR system (Cepheid, Sunnyvale, California, USA) for admission methicillin-resistant Staphylococcus aureus (MRSA) screening of 1336 consecutive paediatric intensive care unit patients (1282 evaluable swab results) were determined using enrichment culture as the reference standard. Twenty (1.6%) swabs were MRSA-positive by enrichment culture (reference test). PCR was more sensitive (0.9, 95% CI 0.68 to 0.99 vs 0.65, 95% CI 0.41 to 0.85) but less specific (0.98, 95% CI 0.98 to 0.99 vs 100%) than chromogenic agar. After introduction of screening no patient developed MRSA infection or acquired MRSA after admission. In the preceding 3 years of screening, 16 patients had MRSA diagnosed after admission, nine presenting with infection. The accuracy of PCR was comparable to previous studies, but the positive predictive value in a low prevalence paediatric population was only 0.49. Screening provided some clinical benefits, to which the early availability of PCR results may have contributed.