Etude n°39

• 39 . An outbreak of pyodermas among neonates caused by ultrasound gel contaminated with methicillin-susceptible Staphylococcus aureus.

OBJECTIVE. To investigate an outbreak of methicillinsusceptible Staphylococcus aureus (MSSA) infections in a neonatal clinic.

DESIGN. Prospective chart review, environmental sampling, and genotyping by two independent methods: pulsed‐field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA polymerase chain reaction (RAPD‐PCR). A case‐control study was performed with 31 controls from the same clinic.

SETTING. A German 1,350‐bed tertiary‐care teaching university hospital.

RESULTS. There was a significant increase in the incidence of pyodermas with MSSA; 10 neonates in good physical condition with no infection immediately after birth developed pyodermas. A shared spatula and ultrasound gel were the only identified infection sources. The gel contained MSSA and was used for hipjoint sonographies in all neonates. PFGE and RAPD‐PCR patterns from 6 neonates and from the gel were indistinguishable and thus genetically related clones. The case‐control study revealed no significant risk factor with the exception of cesarean section (P=.006). The attack rate by days of hip‐joint sonography between April 15 and April 27, 1994, was 11.8% to 40%.

CONCLUSIONS. Inappropriate hygienic measures in connection with lubricants during routine ultrasound scanning may lead to nosocomial S aureus infections of the skin. To our knowledge this source of S aureus infections has not previously been described.