# P-1089. Community-based transmission networks of Staphylococcus aureus identified through hospital-based active surveillance and whole genome sequencing

## TL;DR

This study uses whole genome sequencing to identify community-based transmission clusters of Staphylococcus aureus among hospitalized patients, revealing patterns linked to specific risk factors.

## Contribution

The study introduces a hospital-based approach using WGS to uncover previously unrecognized community transmission networks of S. aureus.

## Key findings

- Five large MRSA clusters were identified with distinct demographic and clinical characteristics.
- Community transmission was linked to factors like substance use, HIV, and specific geographic or cultural communities.
- Skin and soft tissue infections were common in younger clusters, while bacteremia was more prevalent in older nursing home-associated clusters.

## Abstract

Staphylococcus aureus colonization precedes invasive infection. Hospitalized patients with S. aureus colonization can transmit to other patients, but community-based S. aureus transmissions are not well characterized. We used comprehensive, hospital-wide whole genome sequencing (WGS) of S. aureus isolates coupled with demographic data to characterize community-based S. aureus transmission clusters.

8,567 S. aureus isolates from clinical and surveillance cultures collected between Oct 2022-Dec 2023 underwent WGS, with epidemiological and demographic data pulled from the electronic health record (EHR). Closely related isolates (< 20 single nucleotide polymorphisms) without in-hospital epidemiologic links underwent chart review, looking for community-based transmission clusters. Data was analyzed with Microsoft Excel.

The five largest clusters of closely related isolates lacking in-hospital epidemiologic links were all methicillin-resistant (MRSA). Cluster 1 included 23 patients with clonal complex 8/USA300, 83% were male with mean age 41 years, with high rates of substance use (71%), HIV (52%), and self-reported men who have sex with men (MSM, 35%). Cluster 5 (8 patients, clonal complex 30) had similar demographics as cluster 1 but with higher rates of substance use (87%), with half of patients found down prior to admission. All clinical cultures in clusters 1 and 5 were from skin and soft tissue infections (SSTI). Patients in clusters 2 and 3 (n=27 combined, both clonal complex 5) all resided in Brooklyn, NY, with mean age 67-75 years, 75% had recent nursing home or group home exposure and were more likely to have bacteremia and no SSTI. Patients in cluster 4 (n=9, clonal complex 8) were children with a mean age of 2.5 years, 2/3 of whom had MRSA colonization detected while in the neonatal intensive care unit;1/3 had SSTI and were from Orthodox Jewish communities in Brooklyn.

WGS of S. aureus isolates obtained in the hospital identified large community transmission clusters, highlighting a need to integrate community risk factors with hospital-based infection prevention strategies. Future interventions targeting risk profiles can enhance efforts to prevent hospital-acquired S. aureus infections.

All Authors: No reported disclosures