Epidemiology of Staphylococcus aureus in neonates on admission to a Chinese neonatal intensive care unit

Abstract

Little is known about the molecular epidemiology of Staphylococcus aureus in Chinese neonatal intensive care units (NICUs). We describe the molecular epidemiology of S. aureus isolated from neonates on admission to Beijing Children's Hospital. Methods From May 2015-March 2016, nasal swabs were obtained on admission from 536 neonates. Cultures were also obtained from body sites with suspected infections. S. aureus isolates were characterized by staphylococcal chromosomal cassette (SCCmec) type, staphylococcal protein A (spa) type, multilocus sequence type (MLST), sasX gene, antimicrobial susceptibility and cytotoxicity. Logistic regression assessed risk factors for colonization. Results Overall, 92 (17%) infants were colonized with S. aureus and 20 (3.7%) were diagnosed with culture-positive S. aureus infection. Of the colonized infants, 70% (64/92) harbored methicillin-susceptible S. aureus (MSSA), 30% (28/92) harbored methicillin-resistant S. aureus (MRSA) while 70% (14/20) of infected infants were culture-positive for MRSA, 30% (6/20) were culture-positive for MSSA. Risk factors for colonization included female sex, age 7-28 days, higher birthweight (3270 IQR [2020-3655] grams) and vaginal delivery (p<0.05). The most common MRSA and MSSA clones were community-associated ST59-SCCmecIVa-t437 (60%) and ST188-t189 (15%), respectively. The sasX gene 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.

Surveillance for Colonization, Transmission, and Infection With Methicillin-Susceptible Staphylococcus aureus in a Neonatal Intensive Care Unit

“…Indeed, colonization with S aureus , regardless of methicillin resistance, has frequently been described as one of the major risk factors for the acquisition of S aureus infections, both in adult and pediatric populations. 1 , 33 , 34 Length of stay in the NICU has been reported as one of the contributing factors for S aureus infections, 6 , 35 which can be influenced by birth weight, gestational age, and other clinical parameters. 36 Because these parameters are only marginally modifiable, decolonization measures have been suggested as an option to prevent S aureus infections in this population.…”

Methicillin-Resistant Staphylococcus Aureus Transmission and Hospital-Acquired Bacteremia in a Neonatal Intensive Care Unit in Greece

“…In a study from USA among 3536 neonates from 2007 to 2011, 2% had a culture grow MRSA [3]. A rate of 5,2% MRSA colonization among 536 neonates was recently reported from China for the period 2015-2016 [11]. Similar ndings come from USA, where 3,9% of 3700 neonates from a single NICU were colonized [12].…”

Perinatal Gram-Positive Bacteria Exposure Elicits Distinct Cytokine Responses In Vitro

“…Our results show that S. agalactiae induced prominent inflammatory responses in UBMC, indicating that the neonatal immunity is readily responsive to these bacteria components. Still more potent was the response of UBMC to S. aureus lysates, a commensal bacterium that is among the most common causes of chorioamnionitis, preterm birth, and late-onset sepsis in very-low birth weight infants [ 19 ]. Rather than stimulating MCP-1, S. agalactiae and S. aureus elicited higher MIP-1α release than E. faecalis .…”

“…aureus colonization [ 17 ], which is a risk factor for subsequent S. aureus infection. Such infections are among the most common causes of late-onset sepsis, for example, in very-low birth weight neonates [ 18 , 19 ].…”