Neonatal Exposure to Staphylococcus aureus in the Neonatal Intensive Care Unit: Identifying Reservoirs Among Colonized Healthcare Workers and Parents

Abstract

Background:Staphylococcus aureus (S. aureus) is the second most common cause of healthcare-acquired infections in neonates. S. aureus colonization is a known risk factor for invasive disease. Aside from healthcare workers (HCWs), recent data suggest that parents are important reservoirs of S. aureus in the neonatal intensive care unit (NICU). S. aureus typically colonizes the nares, but it can also colonize other anatomic locations such as the throat. Objective: Our objectives were to identify and compare S. aureus colonization among HCWs and parents and to identify and compare different sites of S. aureus colonization. Methods: Between April 2015 and July 2016, we performed 4 point-prevalence surveys and collected nares and throat swabs from HCWs (nurses, respiratory therapists, nurse practitioners, and physicians) at a quaternary-care NICU. During an overlapping period, we screened parents of neonates in the NICU for S. aureus colonization using nares, throat, groin, and perianal cultures as a part of an ongoing randomized control trial. Cultures from both studies were collected using standardized methods. ESwabs were used to collect samples, which were inoculated into broth for enrichment and subsequently cultured onto chromogenic agar to differentiate between MSSA and MRSA. Results: The prevalence of methicillin susceptible S. aureus (MSSA) colonization was 46% (105/226) in HCWs and 28% (239/842) in parents. The prevalence of methicillin resistant S. aureus (MRSA) colonization was 2.2% (5/226) in HCWs and 2.2% (19/842) in parents. Of those who were colonized with S. aureus, 35% (79/226) of HCWs and 46.5% (160/344) of parents had nares and throat colonization while 11.5% (26/226) of HCWs and 12.2% (42/344) of parents had only throat colonization but not nares colonization. Of those who were MRSA colonized, 1.3% (3/226) of HCWs and 1.8% (15/842) of parents had a positive nares and throat culture as compared to 0.9% (2/226) of HCWs and 0.2% (2/842) of parents had only positive throat cultures. Additionally, 68% (175/257) were colonized with S. aureus at any swabbed site including nares, throat, groin, or perinanal areas. However, only 30% (77/257) of parents had only nares colonization as compared to 58.8% (151/257) had throat and nares colonization, 38.1% (98/257) had nares and groin colonization, and 37.4% (96/257) had nares and perianal colonization. Conclusions: HCWs had greater prevalence of S. aureus colonization compared to parents. As expected, the nares was the most common site of MSSA and MRSA, but a large proportion of S. aureus colonized HCWs and parents had only throat colonization. Given the prevalence of S. aureus in non-nares sites of HCWs and parents in the NICU, further studies should examine the role of non-nares carriers in the transmission of S. aureus in this population.

Funding: None

Disclosures: Aaron Milstone reports consultancy with Becton Dickinson.