Changes in Rate of Methicillin-Resistant Staphylococcus Infection in a Community Neonatal Intensive Care Unit Before and During the COVID-19 Pandemic

BACKGROUND: Methicillin-Resistant Staphylococcus aureus (MRSA) infections represent a significant healthcare challenge, particularly in neonatal intensive care units (NICUs) where patients experience increased morbidity and mortality. MRSA transmission has not been well studied in the setting of enhanced infection precautions (EIP) taken during the COVID-19 pandemic - such as universal masking and enhanced hand hygiene. OBJECTIVE: This retrospective cohort study compared rates of MRSA infection in a community NICU during two distinct time periods: January 2016 to March 2020 (Pre-EIP: before EIP was instituted) and April 2020 to December 2022 (With-EIP: after EIP was instituted). METHODS: During the study period, 74 neonates admitted to the NICU tested positive for MRSA (56 Pre-EIP and 18 With-EIP). MRSA cases were collected using laboratory and electronic medical record review. Cases were reported as infections per 1,000 patient days (IP-1000). Statistical analysis with two-sample t-tests assuming unequal variance and chi squared tests for independence were performed. RESULTS: There was a significant decrease in MRSA IP-1000 from 1.90 Pre-EIP to 0.93 With-EIP (p=0.0006). The prevalence of MRSA clusters, defined as three infections within a 30-day period, decreased from 0.27 Pre-EIP compared to 0.03 With-EIP (p=0.0004). However, The Pre-EIP cohort had a younger average gestational age (30.2 vs 33.8 weeks, p=0.001), higher rates of very low birth weight (59% vs 28%, p=0.021), and fewer inborn neonates (88% vs 100%, p=0.115) - factors known to increase risk of MRSA infection. CONCLUSION: These findings suggest that EIP may have contributed to the reduction in MRSA clusters observed in this community NICU. Findings are limited by differences in cohort risk factors, small study population, variabilities in infection precautions throughout the pandemic, and the inherent bias of retrospective cohort analysis. This underscores the importance of prevention strategies and highlights the potential benefits of continued enhanced infection precautions in reducing the transmission of MRSA in vulnerable inpatient populations.