Hongwei Zhou

The increasing incidence of carbapenem-resistant Enterobacteriaceae (CRE) -mediated hospital infections in China prompted a need to investigate the genetic basis of emergence of such strains. A nationwide survey was conducted in China covering a total of 1105 CRE strains collected from 25 geographical locales with results showing that acquisition of two carbapenemase genes, bla KPC-2 and bla NDM , was responsible for phenotypic resistance in 90% of the CRE strains tested (58% and 32% respectively), among which several major strain types, such as ST11 of K. pneumoniae and ST131/ST167 of E. coli, were identified, suggesting that dissemination of specific resistant clones is mainly responsible for emergence of new CRE strains. Prevalence of the fosA3 gene which mediates fosfomycin resistance, was high, while the colistin resistance determinant mcr-1 was rarely present in these isolates. Consistently, the majority of the bla NDM -bearing plasmids recoverable from the test strains belonged to IncX3, which contained a common core structure, bla NDM -blaMBL-trpF. Likewise, the core structure of ISKpn27bla KPC-2 -ISKpn2 was observed among plasmids harboring the bla KPC-2 gene, although they were genetically more divergent. In conclusion, the increasing prevalence of CRE strains in China is attributed to dissemination of conservative mobile elements carrying bla NDM or bla KPC-2 on conjugative and non-conjugative plasmids.

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is emerging as a worldwide public health concern; however, the long-term molecular epidemiological surveillance of clinical CRKP in China is limited. We conducted a retrospective observational study (2008–2018) to assess the prevalence, susceptibility, risk factors and molecular epidemiology of clinical CRKP isolates. We found the prevalence of CRKP increased from 2.5%, 2008 to 15.8%, 2018. CRKP were significantly more frequent among hospitalized patients from ICU, and it was significantly more likely to be isolated from the capital city (Hangzhou) and the patients aged ≥60 years. Additionally, seasons and specimen types were associated with CRKP infections. The main CRKP sequence type (ST) was ST11, and blaKPC-2 was the most prevalent gene variant. Together these data reveal an increasing incidence and resistance trends among CRKP, especially the ST11-blaKPC-2-CRKP, in Zhejiang, during 2008–2018. Our findings are important for hospitals to limit its dissemination and optimize antibiotic administration.