Spatial analysis of methicillin-resistantStaphylococcus aureuscarriage (MRSA) at hospital admission in a livestock dense region

Summary Title Spatial analysis of methicillin-resistant Staphylococcus aureus carriage (MRSA) screening yield at hospital admission in a livestock-dense region Purpose In the Netherlands, patients with a risk factor for methicillin-resistant Staphylococcus aureus (MRSA) carriage, such as foreign hospital stay and contact with livestock (pigs, veal calves and/or broilers) are actively screened upon hospital admission. This study aimed to give insight in the geographical clustering patterns of MRSA carriage among these patients in a livestock-dense region. Methods A retrospective study was performed using medical records and laboratory results of MRSA screened patients admitted to seven hospitals in the provinces of Gelderland and Noord-Brabant, covering the period from 01/2011 to 02/2017. SaTScan spatial scanning identified cluster areas with an increased MRSA carriage risk in postal codes compared to the surrounding areas. Results 15 546 patients were included, among which 10.0% (n=1499) were MRSA carriers. Four significant, typically highly pig-dense MRSA carriage hotspots were identified, where the relative risk of carriage ranged from 2.1 to 3.4 compared to the surrounding area. Conclusion MRSA carriage risk clustered in certain areas, suggesting an association between livestock density (mainly pigs) and the MRSA carriage risk for the screened population at hospital admission. It needs to be explored when proximity (not contact) to livestock should be considered a risk factor. Considering analytical difficulties we encountered it is recommended to harmonize culture methods and data acquisition across hospitals to facilitate analysis for improving MRSA screening policy. Impacts The fraction MRSA carriers among patients with livestock contact notified in the hospital system in this study was 22.7%, showing the effectiveness of the Search and Destroy policy. MRSA carriage in the Dutch Province Gelderland is clustered in certain hotspots, located in pig-dense areas. Culture methods and data acquisition should be harmonized across hospitals to facilitate analysis for improving MRSA screening policy.