Nosocomial transmission of community-acquired methicillin-resistant Staphylococcus aureus in a well-infant nursery of a teaching hospital

Background: Infection due to community-acquired strains of methicillin-resistant Staphylococcus aureus (CA-MRSA) has been reported with increasing frequency. Herein is described the nosocomial transmission of CA-MRSA involving 13 neonates and two mothers in a well-infant nursery in a teaching hospital in Saudi Arabia. Methods: From October to November 2009, temporally related cases of CA-MRSA skin and soft-tissue infection occurred in newborns shortly after discharge from a well-infant nursery. An outbreak investigation including case identification, review of medical records, staff screening, environmental cultures, pulsed-field gel electrophoresis, and a case-control study were conducted. Controls were selected from among asymptomatic neonates admitted to the same nursery and matched for the day of admission. Results: Fifteen subjects were found to be CA-MRSA positive: 13 neonates and two mothers. The crude attack rate among neonates was 5.5% during the outbreak period. All 13 neonates presented with skin and soft-tissue infection; one of the mothers had mastitis and a breast abscess. The source of the outbreak was not evident. Pulsed-field gel electrophoresis showed that all of the tested isolates from one strain except one, all contained the staphylococcal cassette chromosome mec (SCCmec) type IV. Conclusion: MRSA strains that initially emerged in the community are now causing disease in health-care settings. Adherence to standard infection control practices, including consistent hand hygiene, in newborn nurseries is important to prevent transmission in such settings.