Nasal methicillin-resistant Staphylococcus aureus carriage among hospitalized patients before and after COVID-19 pandemic in a regional hospital in taiwan.

Background: Strict mask wearing and handwashing were implemented in hospital settings during COVID-19 pandemic in Taiwan. To explore if nasal methicillin-resistant Staphylococcus aureus (MRSA) carriage rate among inpatients in the hospital changed before and after COVID-19, we conducted this study.

Methods: Patients who were admitted to a regional hospital in central Taiwan during one week in 2012 and 2023, respectively, were enrolled. A nasal swab from each subject was obtained for MRSA detection after a written informed consent was obtained. Risk factors of MRSA carriage, and microbiologic characteristics of MRSA were analyzed.

Results: Overall, nasal MRSA carriage rate was 6.2 % (31/502) in 2012 and 8.0 % (40/499) in 2023. In addition to pediatric patients, risk factors significantly associated with MRSA carriage included allergic rhinitis, chest tube insertion, chronic obstructive pulmonary disease in 2012 and recent positive MRSA culture, antimicrobial usage within previous year in 2023. In 2012, the two most common strains were ST 59/pulsotype C/staphylococcal chromosomal cassette (SCCmec) IV/Panton-Valentine leucocidin (PVL)-negative (35.5 %) and ST 59/pulsotype D/SCCmec V/PVL positive (19.4 %) while the two most common strains shifted to ST 45 (and its single locus variant)/pulsotype AK/SCCmec IV/PVL-negative (30.0 %) and ST 8/pulsotype AI/SCCmec IV/PVL positive (22.5 %) in 2023.

Conclusions: Nasal MRSA carriage rate among inpatients in the hospital setting was not affected by the COVID-19 pandemic in Taiwan. Molecular characteristics of colonizing MRSA isolates shifted from two local endemic community strains of ST 59 to two emerging imported strains of ST 45 and ST 8.