Epidemiology ofStaphylococcus aureusin Neonates on Admission to a Chinese Neonatal Intensive Care Unit

PurposeLittle is known about the molecular epidemiology ofStaphylococcus aureusin Chinese neonatal intensive care units (NICUs). We describe the molecular epidemiology ofS. aureusisolated from neonates on admission to Beijing Children’s Hospital.MethodsFrom May 2015-March 2016, nasal swabs were obtained on admission from 536 neonates. Cultures were also obtained from body sites with suspected infections.S. aureusisolates were characterized by staphylococcal chromosomal cassette (SCCmec) type, staphylococcal protein A (spa) type, multilocus sequence type (MLST),sasXgene, antimicrobial susceptibility and cytotoxicity. Logistic regression assessed risk factors for colonization.ResultsOverall, 92 (18%) infants were colonized withS. aureusand 23 (4%) were diagnosed with culture-positiveS. aureusinfection. Of the colonized infants, 72% harbored MSSA, while 74% of infected infants were culture-positive for MRSA. Risk factors for colonization included female sex, age 7-28 days, birthweight and vaginal delivery. The most common MRSA and MSSA clones were community-associated ST59-SCCmecIVa-t437 (60%) and ST188-t189 (15%), respectively. ThesasXgene was not detected. Some MSSA isolates (16%) were penicillin-susceptible and some MRSA isolates (18%) were oxacillin-susceptible. MRSA and MSSA had similar cytotoxicity, but colonizing strains were less cytotoxic than strains associated with infections.ConclusionsS. aureuscolonization was common in infants admitted to our NICU and two community-associated clones predominated. Several non-modifiable risk factors forS. aureuscolonization were identified. These results suggest that screening infants forS. aureusupon admission and targeting decolonization of high-risk infants and/or those colonized with high-risk clones could be useful to prevent transmission.