This month, Loora Grünvald, Resident in infectious diseases at University of Tartu, Estonia, is reviewing:
Nurjadi D, Eichel VM, Tabatabai P, et al. Original Investigation: Infectious Diseases Surveillance for Colonization, Transmission, and Infection With Methicillin-Susceptible Staphylococcus aureus in a Neonatal Intensive Care Unit. JAMA Network Open. 2021;4(9):e2124938.
Why is this important?
Staphylococcus aureus, both methicillin-resistant (MRSA) and methicillin-susceptible (MSSA), infections are among the leading causes of healthcare-associated infections in neonatal intensive care units (NICUs). Regardless, the number of studies done on MSSA is limited compared to MRSA, although infections with MSSA might be even more important in terms of morbidity and mortality. As colonization with S. aureus is considered a significant risk factor for acquiring infections in NICUs, it is important to understand the colonization and transmission dynamics in newborns in order to reduce infections.
What was done in this study?
A retrospective cohort study was performed at the NICU of the Heidelberg University Hospital (tertiary hospital) during a 2-year period from January 1, 2018 to December 31, 2019. A total of 590 newborns were included, of whom 80.9% were preterm and 71.5% were delivered via cesarean section.
The primary end point was S. aureus infection during hospitalization with S. aureus colonization as exposure. Weekly screenings for S. aureus of newborns were conducted together with screening for cephalosporin- and carbapenem-resistant gram-negative bacteria from the nasal and rectal/perianal cavities. Appropriate infection prevention and control measures were implemented, while no routine decolonization measures were put in place for MSSA.
What was observed?
Overall, 135 newborns (22.9%) had S. aureus colonization during the course of their hospital stay and only 1 newborn had MRSA colonization. Of the infants with colonization, 23.7% acquired it within the first 7 days after delivery and 67.4% by the end of the first month of life. During the stay in the NICU, 10 of all the newborns in the cohort had S. aureus infection, the acquisition of which was strongly associated with previous colonization with S. aureus.
Colonization with S. aureus was associated with low birth weight, longer median length of stay and surgical delivery.
Key takeaway points
The proportion of newborns colonized with S. aureus in this study is consistent with the expected general colonization degree in the population, so these findings may not be pathological. The acquisition of S. aureus was a rare event, but colonization with the bacteria appeared one a major risk factors for acquiring infection. Parent-infant transmission is regarded as one of the most probable acquisition routes for S aureus colonization in newborns. Molecular typing, along with epidemiological patient data and transmission patterns, suggests the involvement of healthcare workers as a transmission vector and warrants further scrutiny.