Molecular characterization of carbapenem-resistant Enterobacteriaceae and emergence of tigecycline non-susceptible strains in the Henan province in China: a multicentrer study

INTRODUCTION: Carbapenem-resistant Enterobacteriaceae (CRE) have been responsible for nosocomial outbreaks worldwide and have become endemic in several countries. HYPOTHESIS/GAP STATEMENT: To better understand the epidemiological trends and characteristics of CRE in the Henan province. AIM: We assessed the molecular epidemiological characteristics of 305 CRE strains isolated from patients in 19 secondary or tertiary hospitals in ten areas of the Henan province in China. METHODOLOGY: A total of 305 CRE isolates were subjected to multiple tests, including in vitro antimicrobial susceptibility testing, PCR for carbapenemase genes bla (KPC), bla (NDM), bla (IMP), bla (VIM), bla (OXA)-(48-like). Tigecycline-resistant genes ramR, oqxR, acrR, tetA, rpsJ, tetX, tetM, tetL were analysed in five tigecycline non-susceptible carbapenem-resistant Klebsiella pneumoniae isolates (TNSCRKP). Additionally, multilocus sequence typing (MLST) was performed for carbapenem-resistant K. pneumoniae (CRKP). RESULTS: The most common CRE species were K. pneumoniae (234, 77 %), Escherichia coli (36, 12 %) and Enterobacter cloacae (13, 4 %). All strains exhibited multi-drug resistance. Overall, 97 % (295/305) and 97 % (297/305) of the isolates were susceptible to polymyxin B and tigecycline, respectively. A total of 89 % (271/305) of the CRE isolates were carbapenemase gene-positive, including 70 % bla (KPC), 13 % bla (NDM), 6 % bla (IMP), and 1 % combined bla (KPC)/bla (NDM) genes. K. pneumoniae carbapenemase (KPC) was the predominant carbapenemase in K. pneumoniae (87 %), whereas NDM and IMP were frequent in E. coli (53 %) and E. cloacae (69 %), respectively. Mutations in the ramR, tetA, and rpsJ genes were detected in five TNSCRKP. Moreover, 15 unique sequence types were detected, with ST11 (74 %), ST15 (9 %) and ST2237 (5 %) being dominant among K. pneumoniae strains. CONCLUSION: A high proportion of CRE strains were carbapenemase-positive, and five carbapenem-resistant K. pneumonia isolates were tigecycline non-susceptible, indicating a need for the ongoing surveillance of CRE and effective measures for the prevention of CRE infections.