Molecular epidemiology of carbapenemase-producing Enterobacterales in Finland, 2012-2018

Carbapenemase-producing Enterobacterales (CPE) pose an increasing threat to patient safety and healthcare systems globally. We present molecular epidemiology of CPE in Finland during 2012-2018 with detailed characteristics of CPE strains causing clusters during the same time period. All Finnish clinical microbiology laboratories send Enterobacterales isolates with reduced susceptibility to carbapenems or isolates producing carbapenemase to the reference laboratory for further characterization by whole genome sequencing (WGS). In total, 231 CPE strains from 202 patients were identified during 2012-2018. Of the strains, 59% were found by screening and 32% from clinical specimens, the latter were most commonly urine. Travel and/or hospitalization history abroad was reported for 108/171 strains (63%). The most common species were Klebsiella pneumoniae (45%), Escherichia coli (40%), and Citrobacter freundii (6%), and the most common carbapenemase genes bla_NDM-like (35%), bla_OXA-48-like (33%), and bla_KPC-like (31%). During 2012-2018, the annual number of CPE strains increased from 9 to 70 and different sequence types from 7 to 33, and bla_OXA-48-like genes became the most prevalent. Of the clusters, 3/8 were linked to traveling or hospitalization abroad and 5/8 were caused by K. pneumoniae clone clonal complex 258. Most of the clusters were caused by K. pneumoniae producing KPC. High variety among different sequence types indicates that majority of CPE cases detected in Finland are likely imported from foreign countries. Nearly one-third of the cases are not found by screening suggesting that there is hidden transmission occurring in the healthcare settings.