Klebsiella pneumoniae Carbapenemase Producers in South Korea between 2013 and 2015

Abstract

Between 2014 and 2015, the <i>Klebsiella pneumoniae</i> carbapenemase (KPC) was becoming endemic in South Korea. To assess this period of transition, we analyzed KPC producers in terms of molecular epidemiology. A total of 362 KPC-producing <i>Enterobacteriaceae</i> strains, including one from 2013, 13 from 2014, and 348 from 2015, were actively collected from 60 hospitals throughout the peninsula. Subtypes of KPC were determined by PCR and direct sequencing, and isotypes of Tn<i>4401</i> (the transposon flanking the <i>bla</i>_KPC gene) were specified by PCR using isotype-specific primers and direct sequencing. Sporadic occurrence of KPC-producing <i>Enterobacteriaceae</i> was initially observed around Seoul, which is the most crowded district of the country, and these strains rapidly disseminated in 2014, to the other parts of the country in 2015. The bacterial clones responsible for the extreme epidemiological transition were <i>K. pneumoniae</i> ST307 (46.2%) and ST11 (21.3%). Less frequently, <i>E. coli</i> (4.7%), <i>Enterobacter</i> spp. (1.4%), and other <i>Enterobacteriaceae</i> members (1.7%) producing the enzyme were identified. The <i>bla</i>_KPC-2 gene bracketed by Tn<i>4401a</i> (72.1%) was the most prevalent mobile genetic element responsible for the dissemination, and the same gene carried either by Tn<i>4401b</i> (2.2%) or Tn<i>4401c</i> (6.6%) was identified at a lesser frequency. The genes <i>bla</i>_KPC-3 (1.6%) and <i>bla</i>_KPC-4 (6.4%), both flanked by Tn<i>4401b</i>, were occasionally identified. This study showed endemic dissemination of KPC producers in 2015 due to a clonal spread of two <i>K. pneumoniae</i> strains. Further systemic surveillance is needed to monitor dissemination of KPC-producers.