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 10² 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.