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

OBJECTIVE: To investigate an outbreak of methicillin-susceptible 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 hip joint 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.