Ann Lab Med 2018; 38(1): 17-22
Extensively Drug-Resistant Escherichia coli Sequence Type 1642 Carrying an IncX3 Plasmid Containing the blaKPC-2 Gene Associated with Transposon Tn4401a
Seri Jeong, M.D.1, Jung Ok Kim, B.S.2, Eun-Jeong Yoon, Ph.D.2, Il Kwon Bae, Ph.D.3, Woonhyoung Lee, M.D.1, Hyukmin Lee, M.D.2, Yongjung Park, M.D.4, Kyungwon Lee, M.D.2, and Seok Hoon Jeong, M.D.2
Department of Laboratory Medicine1, Kosin University College of Medicine, Busan; Department of Laboratory Medicine and Research Institute of Bacterial Resistance2, Yonsei University College of Medicine, Seoul; Department of Dental Hygiene3, College of Medical and Life Science, Shilla University, Busan; Department of Laboratory Medicine4, National Health Insurance Service Ilsan Hospital, Ilsan, Korea
Corresponding author: Seok Hoon Jeong
Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Gangnam Severance Hospital, Yonsei University College of Medicine, 211 Eonju-ro, Gangnam-gu, Seoul 06273, Korea
Tel: +82-2-2019-3532
Fax: +82-2-2019-4822
Received: April 24, 2017; Revised: May 29, 2017; Accepted: September 7, 2017; Published online: January 1, 2018.
© Korean Society for Laboratory Medicine. All rights reserved.

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Background: Extensively drug-resistant (XDR) Enterobacteriaceae carrying the blaKPC gene have emerged as a major global therapeutic concern. The purpose of this study was to analyze the complete sequences of plasmids from KPC-2 carbapenemase-producing XDR Escherichia coli sequence type (ST) 1642 isolates.
Methods: We performed antimicrobial susceptibility testing, PCR, multilocus sequence typing (MLST), and whole-genome sequencing to characterize the plasmid-mediated KPC-2-producing E. coli clinical isolates.
Results: The isolates were resistant to most available antibiotics, including meropenem, ampicillin, ceftriaxone, gentamicin, and ciprofloxacin, but susceptible to tigecycline and colistin. The isolates were identified as the rare ST1642 by MLST. The isolates carried four plasmids: the first 69-kb conjugative IncX3 plasmid harbors blaKPC-2 within a truncated Tn4401a transposon and blaSHV-11 with duplicated conjugative elements. The second 142-kb plasmid with a multireplicon consisting of IncQ, IncFIA, and IncIB carries blaTEM-1b and two class 1 integrons. This plasmid also harbors a wide variety of additional antimicrobial resistance genes including aadA5, dfrA17, mph(A), sul1, tet(B), aac(3’)-IId, strA, strB, and sul2.
Conclusions: The complete sequence analysis of plasmids from an XDR E. coli strain related to persistent infection showed the coexistence of a blaKPC-2–carrying IncX3-type plasmid and a class 1 integron-harboring multireplicon, suggesting its potential to cause outbreaks. Of additional clinical significance, the rare ST1642, identified in a cat, could constitute the source of human infection.
Keywords: Escherichia coli, ST1642, blaKPC, Tn4401a, IncX3

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