Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections remain a significant source of morbidity for neonates in the intensive care unit. So when a MRSA outbreak is suspected, it is extremely important to act fast and make the right call. Recently epiXact® was used to investigate a putative MRSA outbreak in a NICU at a large hospital that turned out to have unexpected implications for the microbiology lab.
EpiXact was requested to determine whether a series of MRSA cases in the NICU was community or hospital acquired. EpiXact provided genomic evidence within a day that showed that the samples were non-clonal despite the unusual grouping of cases within a short period of time. The clear and definitive results enabled the infection control team to stand down from a set of planned interventions with confidence.
But the investigation also uncovered a surprising genomic finding. One of the isolates identified as MRSA via growth on selective culture media was missing the resistance genes typically associated with methicillin resistance (mecA, mecC). The microbiology lab was informed immediately. Their investigation uncovered that the cause of this discrepancy was a secondary brand of selective media, sourced from a new vendor due to supply constraints caused by the COVID-19 pandemic, which was permitting breakthrough growth of MSSA and leading to a false-positive MRSA result. Not only did epiXact provide the definitive genomic data to rule-out a MRSA transmission, but it uncovered a quality issue with a new vendor.
Decisions made in the face of an outbreak situation can have potentially significant consequences to the hospital, whether it is ruling in or ruling out possible transmission. The genomic data provided by epiXact helped this institution avoid unnecessary infection control interventions and maintain quality control within their microbiology lab.
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