Epidemiological characteristics of carbapenem-resistant Enterobacteriaceae collected from 17 hospitals in Nanjing district of China
Hui Zhou, Kui Zhang, Wei Chen, Junhao Chen, Jie Zheng, Chang Liu, Cheng Li, Wanqing Zhou, Han Shen, Xiaoli Cao
Abstract
Abstract Objective In total, 97 carbapenem-resistant Enterobacteriaceae (CRE) were collected from 17 hospitals located in Nanjing, Southeast China, and analyzed for epidemiological characteristics. Methods Antimicrobial susceptibility was determined; followed by determination of the prevalence of resistance determinants, including extended-spectrum β-lactamase (ESBLs), plasmid-mediated AmpC enzyme (pAmpCs), plasmid-mediated quinolone resistance genes (PMQRs), fosfomycin resistance gene and exogenously acquired 16S rRNA methyltransferase (16S-RMTase) using PCR and DNA sequencing. The sequence types (STs) of CRE were determined by multi-locus sequence typing (MLST). The plasmid profiles were detected by PCR-based replicon typing (PBRT). Results All the CRE strains displayed high MIC 50 and MIC 90 for nearly all clinical available antibiotics, except for aztreonam/avibactam, minocycline, ceftazidime/avibactam, tigecycline, and colistin. KPC-2 (79.4%) and NDM (19.6%) were the main carbapenemases, CTX-M (76.3%) and SHV (60.8%) were the predominant ESBLs. In addition, oqxAB (70.1%) and qnr (63.9%) were the major PMQRs; rmtB (47.4%) was the main 16S-RMTase; fosA (76.3%) and fosA3 (37.1%) were the fosfomycin resistance gene. PBRT analysis showed presence of IncR (66.0%) and IncFII (64.9%) replicon types in the majority of the isolates, followed by IncFIB (46.4%) and IncX3 (16.5%). The IncFII and IncR replicon-types were found mainly in K. pneumoniae (68.8%), whereas the IncX3 replicons dominated in E. coli isolates (100.0%). The three dominating MLST-types ST11, ST15 and ST268 comprised 68.0% of the 77 K. pneumoniae . Seven distinct STs were identified among 8 E. coli. Conclusions The treatment for infections caused by CRE isolates is challenged by the presence of multiple resistance determinants and plasmid replicons. Our results highlighted the expansion of bla KPC-2 carrying K. pneumoniae ST11, the new emergency of single bla NDM-5 carrying K. oxytoca ST36 , as well as bla IMP-4 and bla NDM-1 co-carrying E. cloacae ST418, which alert us on the urgency for antimicrobial resistant surveillance, to prevent dissemination of these highly transmissible and dangerous lineages.