Background: Six babies infected with Staphylococcus aureus occurred in a neonatal intensive care unit (NICU) over a period of 2 months, which was successfully controlled with the aid of molecular typing of the isolates.

Methods: We examined the staphylococcal toxins, mecA and tst gene PCR, and repetitive-element PCR (rep-PCR) typing in S. aureus isolated from the clinical specimens of infected babies, nasal swabs of the patients and medical personnels in a NICU, and environmental equipments.

Results: Among all S. aureus isolates tested, they were toxic shock syndrome toxin 1 (TSST-1)producing methicillin-resistant S. aureus (MRSA) who have mecA and tst gene, and one identical repPCR pattern all, except 3 MRSA isolated from the nasal swabs of 2 non-infected patients and 1 medical personnel.

Conclusions: It was demonstrated that TSST-1 producing MRSA became epidemic in the NICU as a result of the spread of a single clone. (Korean J Clin Microbiol 2002;5(1):21-25)