OHW 90 - Methicillin-resistant Staphylococcus Aureus Screening of Neonatal Intensive Care Unit Staff in an Outbreak Setting

Background: In December of 2020, our infection prevention (IP) department noted an increase in Methicillin-resistant Staphylococcus aureus (MRSA) isolates over baseline in the Neonatal Intensive Care Unit (NICU). Our hospital sees a steady influx of parents colonized with MRSA and our weekly screening process regularly discovers neonates that subsequently become colonized with MRSA. We attempt to screen the neonates’ mothers at the time of admission.
A doubling of the number of cases per month led to deeper investigation. Epidemiologic data was collected on the neonates and matched to their mother’s screening cultures (when obtained). Sensitivity patterns were matched, and staff noted that a single sensitivity pattern predominated.

Methods: Numerous interventions were attempted but did not impact the epidemic curve. Eventually, leadership and infection prevention (IP) staff concluded that the next step would be to start testing the NICU staff. Screened staff were those epidemiologically linked to the cases. MRSA isolates from patients and staff were characterized by whole genome sequences (WGS) and used to identify those in the cluster in question. 175 coworkers in 6 rings were sequentially tested using polymerase chain reaction with culture if positive and submitted for whole genome sequencing.

Results: A total of six rings of coworkers were identified and sequentially tested. Testing consisted of a MRSA/MSSA (Methicillin-sensitive Staphylococcus aureus) polymerase chain reaction (PCR) followed by a culture if MRSA positive. Of 175 employees tested five were found to be positive. Three of the staff were not part of the cluster by WGS. One employee’s isolate failed to grow. All of these employees were decolonized. Incidentally noted, 30 of the staff were noted to be colonized with MSSA but none associated with any clustering. The NICU has been free of the epidemic strain for the past six months.

Conclusions: In conclusion, only 2.9% of NICU staff were colonized with MRSA.