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

Abstract

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.

Keywords: Carbapenem-resistant Enterobacteriaceae; multi-drug resistance; tigecycline-non-susceptible.

Fig. 1.

Areas included in the study are shaded. Areas with TNSCRKP isolates are denoted with stars.

Fig. 2.

Antimicrobial susceptibility testing results of 305 carbapenem-resistant Enterobacteriaceae isolates.

Fig. 3.

Antimicrobial susceptibility testing results and related characteristics of five TNSCRKP clinical isolates.

Fig. 4.

MLSTs of CRKP isolates at the TLV (triple-locus variants, TLVs) level using goeBURST. The yellow circle denotes the subgroup founder. Number size is proportional to the ST abundance.