Screening patients at admission to Copenhagen hospitals for carriage of resistant bacteria after contact with health care systems abroad, 2016-2019

Objectives. Patients with previous contact to health care systems abroad are routinely screened for resistant bacteria at admission to Copenhagen hospitals. The aim of this study was to present carriage prevalence and geographic risk stratification as well as pheno- and genotypic characterisation of resistant isolates. Methods. We included screening samples analysed at one department of clinical microbiology in Copenhagen from 2016-2019. Patients with previous contact with health care systems abroad within six months were screened at admission for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and carbapenemase-producing organisms (CPO). Isolates were characterized phenotypically and by whole-genome sequencing. The relative frequency of positive findings stratified by geographic regions was correlated to relative frequency of Danish residents’ travel destinations. Results. Of 2849 screening sets included in the study, 103 (3.6%) were positive. One hundred-twenty resistant isolates were detected (36 MRSA, 31 VRE and 53 CPO). The carrier prevalence for MRSA was 1.3%, for VRE 1.1% and for CPO 1.5%. Southern and Western Asia were overrepresented travel destinations in positive screening sets (41%). For VRE, 40% were related to Southern Europe, which also represent 35% of travel destinations. Genotypic characterisation confirmed a heterogenous genomic background reflecting global distribution of resistant clones. Conclusions. Exposure targeted screening identified a substantial number of asymptomatic carriers of MRSA, VRE and CPO with heterogenous genetic background. Although some geographic regions were overrepresented, the complex epidemiology of the different pathogens does not allow a restriction of the screening strategy to certain geographic regions.