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.

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