424 - Containment and Management of an MRSA Outbreak in a Level 3 Community NICU

Publication Number: 2412.424

Michael Brandler, New York-Presbyterian Queens Medical Center, Pelham, NY, United States; Karen Acker, Weill Cornell Medicine, New York, NY, United States; Nishant Prasad, NewYork-Presbyterian Queens, Flushing, NY, United States; Lisa Hartin, NYPQ, Flushing, NY, United States; Jennie G.. Ono, Weill Cornell Medicine, NEW YORK, NY, United States

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infections and outbreaks have long been a scourge of NICUs. Rates of colonization vary, with estimates ranging from 1.5% to 32%. The effect of colonization alone is hard to assess, but as a risk factor for subsequent MRSA infection it may pose a bigger risk than often thought. Additionally, MRSA infection significantly increases length of stay and morbidity, increasing the already high economic and health burden of a NICU stay.

Objective: To describe our investigation of an outbreak of clinical MRSA infections and review the control measures that led to containment.

Design/Methods: We instituted MRSA control measures and testing in consultation with our local Infection Prevention &Control team. All MRSA isolates were genotyped to determine origin, using whole genome sequencing (WGS) at the New York State Department of Health laboratory. Our NICU is a single bay with 3 divided areas. Actions included: a 3-minute surgical scrub at the start of each shift; implementation of "Bare below the elbow"; terminal cleaning of surfaces and equipment; weekly surveillance cultures regardless of prior results, and decolonization. Measures were reinforced with ongoing education and signage. All infants testing positive were on contact isolation for the remainder of their stay. Decolonization included 2% mupirocin to the nares 3 times daily and 2% CHG wipes daily for 7 days, depending on gestational age. Staff screening was not performed.

Results: The outbreak started with 4 clinical infections (Table). MRSA colonization rate went from 82% to under 30% in 2 weeks; it then further declined and was sustained (Figure). There were no new clinical MRSA infections after weekly surveillance began. Overall rate of colonization during the outbreak was 12%. WGS showed the initial isolates were all type 8 with less than 15 single-nucleotide polymorphisms strongly suggesting clonal relatedness. The last baby with clinical infection left on week 20. The last baby born prior to week 20 was discharged on week 35. By week 49, there was no baby present that was born within 6 months of the last clinical infection. The outbreak was declared over at week 53, with no new positive surveillance tests in the previous 7 weeks.

Conclusion(s): We demonstrate that the spread of MRSA can be contained and clinical infection eliminated by strict control measures and decolonization efforts, without need for staff screening. Vigorous and collaborative efforts are critical to maintain adherence to prevention and control measures.

Characteristics of MRSA infections during the outbreak period


MRSA surveillance culture results
Legend: New positive culture results (blue) and weekly overall colonization rate (orange). Routine surveillance cultures began week 11.