First nationwide case - case study on factors associated with emerging methicillin-resistant Staphylococcus aureus spa type t4549 in Denmark, 2022-2023.

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) spa type t4549 is increasingly prevalent in Denmark, yet its epidemiological sources remain unclear. This study aimed to generate hypotheses about possible risk factors that may be associated with MRSA t4549 infections. We conducted a nationwide case - case questionnaire study comparing MRSA t4549 cases to other MRSA types (t002, t008, t127, t304, and t223) reported between January 2022 and November 2023. The analysis, which included descriptive statistics and logistic regression, found that 75% of MRSA t4549 cases were male. Infections were significantly more frequent in the foot (28%) and toe (54%) compared to other MRSA types. Key risk factors identified were contact with pheasants (OR = 8.70; 95%CI 1.25-174.29), participation in indoor team sports (OR = 7.54, 95%CI: 1.58-54.82) and swimming (OR = 4.15, 95%CI: 1.97-9.03). Although the limited number of cases warrants cautious interpretation, it is crucial to emphasize the need for preventive measures at both the individual and sports facility levels. Further environmental studies are needed to clarify the role of the environment and wildlife in MRSA t4549 transmission. The increasing prevalence of this spa type in Denmark underlines the importance of implementing effective public health strategies to reduce the risk of MRSA transmission.