Control of a hospital outbreak with methicillin-resistant Staphylococcus argenteus in The Netherlands, June–September 2023

BACKGROUND: Staphylococcus argenteus belongs to the Staphylococcus aureus complex and causes similar disease. Methicillin-resistant S. argenteus (MRSArg) is rare in the Netherlands. We describe the first hospital outbreak and its management. METHODS: After a healthcare worker linked to a patient with MRSArg bacteremia tested positive, cohort screening of healthcare workers, patients, and family members was performed. Carriers received eradication therapy. Whole-genome multilocus sequence typing (wgMLST) and antimicrobial susceptibility testing were used to characterize isolates and mupirocin resistance. RESULTS: Fifteen (2.6%) MRSArg carriers were detected: 9/317 (2.8%) healthcare workers, 4/238 (1.7%) patients, 2/16 (12.5%) family members; age range 22-88 years, median 55 years. Nine (60%) were complicated and six (40%) uncomplicated carriers. After transfer of one initially negative patient to a nursing home, subsequent positivity led to two carriers among nursing home staff. wgMLST confirmed a single outbreak cluster of 15 isolates, all MLST ST2250. The isolates carried mecA, dfrG, and blaZ, but not PVL. Eradication therapy was started in 13/15 (86.7%) persons, with 84.6% (11/13) successful eradication. Six isolates carried a V588F-mutated ileS gene and had mupirocin MICs of 2-32 mg/L; nine were sensitive. CONCLUSIONS: We report the first successfully controlled MRSArg hospital outbreak in the Netherlands. The outbreak strain was clonally related and showed low-level mupirocin resistance linked to a mutated ileS gene. This work supports the importance of infection prevention and control measures that are applied for MRSA are also effective for MRSArg.