# 404. Genomic surveillance reveals reduced Staphylococcus aureus transmission in semi-private versus multi-bed hospital rooms

## TL;DR

Using genomic surveillance, this study found that Staphylococcus aureus transmission is significantly lower in single and semi-private hospital rooms compared to multi-bed rooms.

## Contribution

This study provides novel evidence on reduced S. aureus transmission in single and semi-private rooms using whole-genome sequencing and real-world hospital data.

## Key findings

- Single rooms had the lowest S. aureus transmission rate (0.5 per 1000 admissions).
- Four-bed rooms had nearly ninefold higher transmission rates compared to single rooms.
- Standard infection control practices may be insufficient in multi-bed settings.

## Abstract

Although single-patient rooms are recommended for hospital design to reduce healthcare-associated infections, construction is costly, and supporting evidence remains limited. Most studies rely on pre/post time series analyses that cannot account for concurrent infection control and antimicrobial stewardship initiatives. To address this gap, we used comprehensive, hospital-wide whole-genome sequencing (WGS) surveillance to compare Staphylococcus aureus transmission rates in single- versus multi-bed rooms during routine clinical operations.

Across two hospitals in an urban health system, ∼3,000 patients per month underwent active S. aureus surveillance using admission nasal swabs. Surveillance and clinical (blood, sputum, wound) isolates collected between October 2022 - December 2023 underwent WGS. Closely related isolates (< 20 single nucleotide polymorphisms) that were epidemiologically linked based on timestamped patient location data were classified as high-probability transmissions. We compared S. aureus transmission rates among single, two-bed, and four-bed rooms, all of which underwent identical cleaning and sporicidal disinfection protocols.

Over 14-months, >5,000 isolates from 4,000 patients underwent WGS, 85% of which were from surveillance cultures. Of admissions, 21% were to single rooms, 59% to two-bedded rooms, and 20% to four-bedded rooms. Transmission risk was lowest in single rooms (0.5 transmissions per 1000 admissions), increased in two-bed rooms (1.2 per 1000 admissions), and was nearly ninefold higher in four-bed rooms compared to single rooms (4.4 transmissions per 1000 admissions).

In this large WGS-based surveillance study, single and semi-private (two-bed) rooms were associated with substantially lower S. aureus transmission rates compared to four-bed rooms. These findings indicate that room occupancy is a modifiable factor in transmission risk and that standard infection control practices may be insufficient; therefore, innovative, continuous disinfection strategies are warranted. Ongoing work is adjusting for potential differences in patient populations across room types to refine estimates of the impact of room occupancy on transmission.

All Authors: No reported disclosures