# Antibiotic resistance characteristics, molecular typing, and potential transmission reservoirs of methicillin-resistant Staphylococcus aureus in patients with postoperative infection

## TL;DR

This study analyzed MRSA in postoperative patients and found potential transmission sources in a hospital surgery department.

## Contribution

The study identifies MRSA reservoirs and resistance patterns in a specific hospital department.

## Key findings

- MRSA strains were found in nasal swabs, environmental samples, and postoperative infections.
- Common MRSA genotypes included t437, t034, and t078, with ST398, ST25, and ST59 as dominant sequence types.
- MRSA showed high resistance to some antibiotics but remained sensitive to vancomycin, ceftaroline, and tigecycline.

## Abstract

The study aimed to assess the antibiotic resistance characteristics and molecular typing of methicillin-resistant Staphylococcus aureus (MRSA) in patients with postoperative infection, as well as potential MRSA reservoirs within the Hand and Foot Surgery department.

Infectious specimens were collected from patients with postoperative infection in the Department of Hand and Foot Surgery at a hospital in Shenyang, China between June 2021 and June 2022. Nasal swab samples were obtained from healthcare workers, patients’ family members, and cleaning staff, and environmental samples were collected from hospital wards. Bacterial identification was performed using a mass spectrometer, and antibiotic susceptibility testing was conducted using the VITEK2-Compact automated bacterial analyzer. Molecular typing was performed via staphylococcal protein A (spa) typing and multilocus sequence typing (MLST).

Among 1,161 nasal swab samples, 25 MRSA strains were detected, giving a detection rate of 2.24%. One MRSA isolate was found in 77 environmental samples. Twenty-nine MRSA strains were identified in 406 postoperative infectious specimens, primarily from wound secretions and pus. Nasal swab-derived MRSA exhibited 100% resistance to benzylpenicillin and oxacillin; greater than 80% resistance to erythromycin and clindamycin; and 100% sensitivity to vancomycin, ceftaroline, and tigecycline. MRSA from infectious specimens exhibited a resistance rate of 86.21% to erythromycin and clindamycin. spa typing detected t437, t034, and t078 as the dominant genotypes, as they accounted for 16.36, 12.73, and 14.55% of isolates, respectively. MLST typing identified ST398, ST25, and ST59 as the predominant sequence types, each representing 19.23, 19.23, and 17.31% of isolates, respectively.

This study identified the molecular typing, antibiotic resistance characteristics, and clonal overlaps suggesting potential transmission reservoirs of MRSA in the Department of Hand and Foot Surgery, providing important guidance for clinical treatment and hospital infection control.