Molecular characterization and phenotypic analysis of multidrug-resistant Escherichia coli and Klebsiella pneumoniae isolates from a tertiary-care hospital in Yunnan Province, China

Due to the increasing number of multidrug-resistant (MDR) isolates of Escherichia coli and Klebsiella pneumoniae reported from the Third People’s Hospital of Yunnan Province, an investigation was conducted to better understand the phenotype and molecular characterization of the local isolates. Twenty three non-duplicate E. coli isolates and nine K. pneumoniae isolates were recovered from hospitalized patients and identified and tested for antimicrobial susceptibility using the VITEKw2 system. Drug-resistant genes were amplified and sequenced, and pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) analyses were performed on the tested isolates. All of the isolates, except for one extensively drug-resistant (XDR) K. pneumoniae isolate, were demonstrated to be MDR, and 100% of the E. coli and K. pneumoniae were resistant to ampicillin, cefuroxime, cefazolin and ceftriaxone. Of the isolates, 69.6% of the E. coli and 100% of the K. pneumoniae isolates were blaCTX-M positive, with CTX-M-55 and CTX-M-15 as the leading genotypes. All K. pneumoniae isolates shared blaSHV genes with the dominant SHV-11 genotype. A total of 87.5% E. coli and 77.8% of K. pneumoniae carried the ISEcp1, 91.3% of E. coli and 77.8% of K. pneumoniae shared the int1 gene, and 44.4% of K. pneumoniae presented the ISCR1 gene. A large genetic heterogeneity of K. pneumoniae and E. coli isolates was confirmed by MLST and PFGE analyses. The high frequency of MDR E. coli and K. pneumoniae in local areas may be a substantial challenge for infection control.