title: Emergence of a hypervirulent carbapenem-resistant Klebsiella pneumoniae isolate from clinical infections in China.
abstract: OBJECTIVE
  Hypervirulent Klebsiella pneumoniae (hvKP) infections occur worldwide, but carbapenem-resistant hvKP strain has rarely been observed.
  
  
  METHODS
  A retrospective study was conducted in 28 cases of carbapenem-resistant K. pneumoniae (CRKP) infections from 9 cities in China. Clinical data were collected from medical records. All the isolates were characterized by antimicrobial susceptibility testing, string test, multilocus sequence typing, and capsular genotyping. All the hypermucoviscous CRKP strains were analyzed by virulence gene profiles, serum killing assay, and mouse lethality assay.
  
  
  RESULTS
  Of 28 CRKP isolates, five were positive for string test. Importantly, one of the hypermucoviscous strains isolated from blood sample was identified as hvKP. The hypervirulent CRKP strain showed highly resistant to carbapenems (MIC > 32 μg/mL), decreased expression of ompK35/36, and ESBLs production. Significantly increased resistance to serum killing and mice mortality were found in the hypervirulent CRKP strain compared to the other CRKPs. Capsular polysaccharide synthesis genotyping revealed that the hypervirulent strain belongs to K2 serotype, while others belong to K-nontypable serotype. The K2 hypervirulent CRKP strain carried rmpA, aerobactin, entB, and mrkD genes.
  
  
  CONCLUSIONS
  The newly emerged hypervirulent carbapenem-resistant K. pneumoniae might cause a serious threat to public health, suggesting an urgent need to enhance clinical awareness and epidemiologic surveillance.
authors: Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China.
authors: Yawei
authors: Y
authors: Zhang
authors: Department of Clinical Laboratory, Union Hospital of Huazhong University of Science and Technology, Wuhan, China.
authors: Ji
authors: J
authors: Zeng
authors: Department of Clinical Laboratory, Xiangya Hospital of Central South University, Changsha, China.
authors: Wenen
authors: W
authors: Liu
authors: Department of Clinical Laboratory, Sir Run Run Shaw Hospital of Zhejiang University, Hangzhou, China.
authors: Feng
authors: F
authors: Zhao
authors: Department of Clinical Laboratory, General Hospital of Tianjin Medical University, Tianjin, China.
authors: Zhidong
authors: Z
authors: Hu
authors: Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China.
authors: Chunjiang
authors: C
authors: Zhao
authors: Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China.
authors: Qi
authors: Q
authors: Wang
authors: Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China.
authors: Xiaojuan
authors: X
authors: Wang
authors: Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China.
authors: Hongbin
authors: H
authors: Chen
authors: Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China.
authors: Henan
authors: H
authors: Li
authors: Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China.
authors: Feifei
authors: F
authors: Zhang
authors: Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China.
authors: Shuguang
authors: S
authors: Li
authors: Department of Infectious Diseases and Clinical Microbiology, Beijing Chao-Yang Hospital of Capital Medical University, Beijing, China.
authors: Bin
authors: B
authors: Cao
authors: Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China. Electronic address: wanghui@pkuph.edu.cn.
authors: Hui
authors: H
authors: Wang
mesh_terms: D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology*; D002681:China / Q000453:epidemiology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D007710:Klebsiella Infections / Q000453:epidemiology / Q000382:microbiology* / Q000401:mortality; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity*; D007928:Lethal Dose 50; D008297:Male; D008499:Medical Records; D051379:Mice; D058885:Multilocus Sequence Typing; D012189:Retrospective Studies; D065288:Serogroup; D014774:Virulence / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems
keywords: Carbapenem-resistance; Clinical features; Hypervirulent K. pneumoniae; Molecular characteristics; Virulence