Improved characterisation of MRSA transmission using within-host bacterial sequence diversity

Area of Science:

• Microbial genomics
• Epidemiology
• Infectious disease transmission

Background:

• Hospital-acquired infections, particularly Methicillin-resistant Staphylococcus aureus (MRSA), are a significant concern.
• Previous genomic studies of MRSA transmission have not fully leveraged data from multiple samples per patient.
• Understanding within-host and between-host transmission dynamics is crucial for effective infection control.

Purpose of the Study:

• To reconstruct MRSA colonization and transmission pathways in a high-transmission hospital setting in Thailand.
• To investigate MRSA transmission dynamics between anatomical sites within individual patients.
• To analyze the between-subject transmission bottleneck and compare a novel approach with single nucleotide polymorphism (SNP) counting.

Main Methods:

• Utilized a large dataset of MRSA genome sequences from multiply-sampled patients.
• Reconstructed individual-level colonization and transmission trees.
• Analyzed transmission between anatomical sites and compared different methods for identifying transmission pairs based on SNP counts.

Main Results:

• Successfully reconstructed MRSA transmission trees, providing detailed insights into colonization patterns.
• Identified repeated transmission or wide bottlenecks for MRSA between anatomical sites within individuals.
• Observed significant variation in transmitted diversity between subjects and determined an optimal SNP threshold of 39 for identifying transmission pairs.

Conclusions:

• Genomic analysis of multiply-sampled patients offers enhanced power for reconstructing MRSA transmission.
• The study provides a refined understanding of within-host and between-host MRSA transmission dynamics in a hospital environment.
• The proposed SNP threshold offers an optimized method for identifying MRSA transmission pairs in clinical settings.