Yawei Zhang1, Ji Zeng2, Wenen Liu3, Feng Zhao4, Zhidong Hu5, Chunjiang Zhao1, Qi Wang1, Xiaojuan Wang1, Hongbin Chen1, Henan Li1, Feifei Zhang1, Shuguang Li1, Bin Cao6, Hui Wang7. 1. Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China. 2. Department of Clinical Laboratory, Union Hospital of Huazhong University of Science and Technology, Wuhan, China. 3. Department of Clinical Laboratory, Xiangya Hospital of Central South University, Changsha, China. 4. Department of Clinical Laboratory, Sir Run Run Shaw Hospital of Zhejiang University, Hangzhou, China. 5. Department of Clinical Laboratory, General Hospital of Tianjin Medical University, Tianjin, China. 6. Department of Infectious Diseases and Clinical Microbiology, Beijing Chao-Yang Hospital of Capital Medical University, Beijing, China. 7. Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China. Electronic address: wanghui@pkuph.edu.cn.
Abstract
OBJECTIVES: 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.
OBJECTIVES: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.