Ann Lab Med 2019; 39(2): 167-175
Identification and Characterization of NDM-1-producing Hypervirulent (Hypermucoviscous) Klebsiella pneumoniae in China
Zhou Liu, M.D.1,2, Yi Gu, M.D.1, Xin Li, M.D.2, Yanyan Liu, M.D.1,3, Ying Ye, M.D.1,3, Shihe Guan, M.D.2, and Jiabin Li, M.D.1,3,4
1Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China; 2Department of Laboratory Medicine, The Second Hospital of Anhui Medical University, Hefei, Anhui, China; 3Anhui Center for Surveillance of Bacterial Resistance, Hefei, Anhui, China; 4Department of Infectious Diseases, Chaohu Hospital of Anhui Medical University, Hefei, Anhui, China
Corresponding author: Jiabin Li, M.D.
Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Jixi Road No. 218, Hefei 230022, China
Tel: +86-551-2922713
Fax: +86-551-2922281
Shihe Guan, M.D.
Department of Laboratory Medicine, The Second Hospital of Anhui Medical University, Furong West, Road No. 678, Hefei 230601, China
Tel: +86-551-63869508
Fax: +86-551-63869400
Received: February 11, 2018; Revised: July 28, 2018; Accepted: October 25, 2018; Published online: March 1, 2019.
© Korean Society for Laboratory Medicine. All rights reserved.

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Background: Carbapenem-resistant hypervirulent (hypermucoviscous) Klebsiella pneumoniae (CR-HMKP) poses a significant public health challenge. We investigated its epidemiology and molecular characteristics in a tertiary care hospital in eastern China.
Methods: CR-HMKP were identified among 106 non-duplicated carbapenem-resistant K. pneumoniae isolates (from June 2013 to September 2017) using the string test. The pulsotype (PT) and sequence type (ST) of CR-HMKP isolates were determined using pulsed-field gel electrophoresis and multilocus sequence typing. Resistance determinants, capsular serotypes, and virulence genes were detected by PCR and sequencing. Representative isolates from each PT were selected, and their virulence phenotypes were established using the serum killing and Galleria mellonella lethality assays.
Results: Of the 106 isolates, 13 (12.3%) were CR-HMKP. Seven were positive for blaNDM-1 and shared the same genotype (PT5/ST1764); the others were positive for blaKPC-2, belonged to ST11, and were divided into four different PTs. The serotype of all blaNDM-1-positive isolates was K64, while that of blaKPC-2-positive isolates were K47 (N=4) and K64 (N=2). The NDM-1-producing HMKP isolates were positive for aerobactin, exhibited high serum resistance, and elicited significantly increased larval mortality compared with the other isolates. All patients had received invasive treatment prior to infection by NDM-1-producing HMKP. The infections occurred between July and August 2016 and were hospital-acquired.
Conclusions: NDM-1-producing HMKP ST1764 isolates were identified; this is the first report worldwide on an outbreak of nosocomial infection caused by these isolates. Effective surveillance and strict infection control strategies should be implemented to prevent CR-HMKP dissemination.
Keywords: Carbapenem-resistant, Hypervirulent, Hypermucoviscous, Klebsiella pneumoniae, NDM-1, Epidemiology, Molecular characteristics

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