Staphylococcal scalded skin syndrome in an extremely low-birth-weight neonate: molecular characterization and rapid detection by multiplex and real-time PCR of methicillin-resistant Staphylococcus aureus.

BACKGROUND

Staphylococcal scalded skin syndrome (SSSS), caused by methicillin-resistant Staphylococcus aureus (MRSA) producing exfoliative toxin (ET), is a life-threatening infection for neonates in neonatal intensive care units (NICUs). SSSS in extremely low-birth-weight (ELBW) neonates is rare. A new class of MRSA (community-acquired MRSA, CA-MRSA) has been emerging in the community. The aim of this study was to characterize MRSA from an ELBW neonate with SSSS, and to develop rapid detection methods for SSSS-associated and emerging pediatric MRSA.

METHODS

An ELBW infant in the NICU developed SSSS on day 16 after birth. Isolated MRSA was genetically characterized and compared with CA-MRSA from bullous impetigo (biCA-MRSA), which is positive for the ET and collagen-adhesin (CNA) genes in many cases, and the Panton-Valentine leucocidin (PVL) gene rarely. Specific primers and probes for five virulence genes (for ETA, ETB, ETD, PVL, CNA) were designed for multiplex polymerase chain reaction (PCR) and real-time PCR.

RESULTS

MRSA strain H5 from SSSS exhibited the genotype (ST91, spa416[t375], agr3, SCCmecIVa, CoaI), and possessed the ETB and CNA genes, similar to ST91 biCA-MRSA (albeit with a divergence). Multiplex PCR detected the ETB and CNA genes of strain H5, and real-time PCR detected strain H5 at as low as 10(2)  CFU/mL. The assays were 100% specific and 100% sensitive, for the five virulence genes.

CONCLUSION

ETB-positive ST91 MRSA, which was very similar to ST91 biCA-MRSA, was isolated from an ELBW infant with SSSS. The multiplex and real-time PCR assays specifically or quantitatively detected SSSS-associated and emerging pediatric MRSA.