Assistant Professor Norton Children's Hospital/University of Louisville University of Louisville Louisville, Kentucky, United States
Background: Previously, we showed that prophylactic monthly mupirocin (MP) treatment of infants in the neonatal intensive care unit (NICU) decreased methicillin resistant Staphylococcusaureus (MRSA) transmission and Staphylococcus aureus (SA) invasive infection, with low (4%) MP resistance.
Objective: We implemented an additional MP treatment on admission and evaluated the effect on MP resistance, MRSA transmission, and invasive infections.
Design/Methods: In December 2013, a 101-bed level IV NICU adopted universal monthly MP administration to the nares. Administration of MP at admission was added in April 2017, then discontinued in November 2018. MRSA colonized infants were identified via weekly surveillance cultures and confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) and E-test. MRSA isolates were identified as MP susceptible (MIC ≤4 μg/mL), intermediate resistant (8-64 μg/mL) or high level resistant (MIC >512 μg/mL) via E-test. A logistic regression model was used to assess MP resistance during three time periods: 1) January 2014-March 2017 (monthly MP only), 2) April 2017-October 2018 (MP at admission and monthly), and 3) November 2018-March 2020 (monthly MP only). A generalized linear model calculated MRSA transmission and SA invasive infections (per 1,000 patient days), and central line associated bloodstream infection (CLABSI) rates (per 1,000 line days) during the 3 periods.
Results: 236 MRSA isolates were evaluated for MP resistance. Of those, 21 were resistant: 5 of 139 (4%) in the first time period, 14 of 53 (26%) in the second, and 2 of 44 (5%) in the third. All but three exhibited high level MP resistance. Increased MP resistance in the second time period was statistically significant (p=0.001), while resistance during the first and third periods was not (p=0.982). Increased MP resistance in the second period correlated with a doubling of MP days of therapy (DOT) per 1,000 patient days per month (from 149 to 305). The average time to MRSA acquisition lengthened during the second period and decreased in the third. However, there were no significant differences in rates of MRSA transmission, SA invasive infections, or CLABSI between the 3 time periods. Conclusion(s): Increased use of MP on admission in a NICU as a strategy to delay MRSA colonization doubled DOT per 1,000 patient days and significantly increased MP resistance. However, increased MP resistance did not correlate with increased rates of MRSA transmission, SA invasive infections, or CLABSI.
Authors/Institutions: Julianne V. Green, University of Louisville, Louisville, Kentucky, United States; Kristina Bryant, University of Louisville, Louisville, Kentucky, United States; Lynette F. Boland, Norton Children's Hospital, Louisville, Kentucky, United States; Gordon G. Stout, University of Louisville, Louisville, Kentucky, United States; Alan D. Junkins, Norton Healthcare, Louisville, Kentucky, United States; James A. Stahl, Norton Children's Hospital, Louisville, Kentucky, United States; Yana Feygin, University of Louisville, Louisville, Kentucky, United States; Sagnik Bhadury, University of Louisville, Louisville, Kentucky, United States; Claudia M. Espinosa, University of South Florida, Tampa , Florida, United States
