Dynamic Networks of Methicillin-Resistant Staphylococcus aureus in Communities Drive Hospital Transmission

Area of Science:

• Infectious Diseases
• Genomics
• Epidemiology

Background:

• The distinction between hospital and community transmission of methicillin-resistant Staphylococcus aureus (MRSA) is blurring.
• Understanding MRSA movement across these interfaces is crucial for effective control.

Purpose of the Study:

• To characterize the transmission dynamics of MRSA between hospital and community settings.
• To analyze the genetic relatedness and introduction pathways of MRSA isolates.

Main Methods:

• Whole-genome sequencing and phylogenetic analysis of MRSA isolates from a tertiary care hospital and community settings.
• Epidemiologic analysis including patient residence and livestock exposure.
• Serial cross-sectional sampling over a 10-year period (2010-2019).

Main Results:

• Phylogenetic analysis identified two major MRSA clades (CC8/t008 and CC5/t002).
• Multiple independent introductions of MRSA lineages from the community into the hospital were observed.
• Community-onset MRSA showed geographic clustering outside urban centers, with rural residence and livestock exposure as risk factors.

Conclusions:

• Hospital MRSA transmission is significantly influenced by community-acquired strains.
• Community MRSA transmission appears sustained, with potential limited feedback from hospital strains.
• Prevention strategies must address community-specific factors alongside hospital-based measures.