Surveillance swabbing for MRSA on neonatal intensive care units – is weekly nasal swabbing the best option?

Abstract

Most paediatric meticillin resistant Staphylococcus aureus (MRSA) infections occur in neonatal units, but evidence for ongoing MRSA surveillance is lacking and practice varies. The aim of this study was to determine the optimal strategy for neonatal MRSA screening according to swab site, gestational age and birth weight. MRSA detection on simultaneous weekly nasal and groin surveillance swabs and suspected infected sites was determined for all admissions to a tertiary neonatal unit over eight years. Twenty one thousand, seven hundred and thirty six surveillance specimens were examined (3,784 admissions). Infants colonised with MRSA were smaller and of lower gestational age compared with uncolonised infants ( p<0.0001). Infants initially positive on groin swabs alone (13/68; 19%) were of significantly greater gestational age and weight at birth compared with infants initially positive on nose swabs/both nose and groin swabs (55/68; 80%). Infants initially identified on groin swabs were all subsequently detected on nasal swabs or discharged within two weeks of age. 18/86 (21%) of MRSA cases were initially detected on swabbing suspected infected sites. Surveillance swabbing identified 43% of infants before MRSA bacteraemia. Eighty five per cent of colonised infants would be detected by weekly nasal swabs and by swabbing suspected infected sites. Groin swabs detect a small number of bigger mature babies who are discharged before two weeks of age.