Investigation of possible clonal transmission of carbapenemase-producing Klebsiella pneumoniae complex member isolates in Denmark using core genome MLST and National Patient Registry Data

Abstract Objectives : The aim of this study was to identify clonally related carbapenemase-producing Klebsiella pneumoniae complex members, which could be involved in outbreaks among hospitalized patients in Denmark, and to identify possible epidemiological links. Methods : From January 2014 through June 2018, 103 isolates belonging to the K. pneumoniae complex were collected from 102 patients. From the WGS data, presence of genes encoding carbapenemase and MLSTs were extracted. Core genome MLST (cgMLST) cluster analysis were performed. Using data from the Danish National Patient Registry (DNPR) and reported travel history, presumptive outbreaks were investigated for possible epidemiological links. Results : The most common detected carbapenemase gene was blaOXA-48, followed by blaNDM-1. The 103 K. pneumoniae complex isolates belonged to 47 ST and cgMLST subdivided the isolates into 80 different complex types. cgMLST identified 13 clusters with 2-4 isolates per cluster. For five of the 13 clusters, a direct link (the patients stayed at the same ward on the same day) could be detected between at least some of the patients. In two clusters, the patients resided simultaneously at the same hospital, but not ward. A possible link (same ward within 1-13 days) was detected for the patients in one cluster. For five clusters detected by cgMLST, no epidemiological link could be detected using data from DNPR. Conclusion : In this study, cgMLST combined with patient hospital admission data and travel information was found to be a reliable and detailed approach to detect possible clonal transmission of carbapenemase-producing Klebsiella pneumoniae complex members.