Resistance Phenotype and Molecular Epidemiology of Carbapenem-Resistant <i>Klebsiella pneumoniae</i> Isolates in Shanghai

Abstract

<b><i>Background:</i></b> The emergence and wide global spread of carbapenem-resistant <i>Klebsiella pneumoniae</i> (CRKP) isolates are of great concern, and the aim of this study was to investigate drug resistance, molecular epidemiology, and genetic relationship of CRKP isolates from patients in Shanghai, China. <b><i>Methods:</i></b> A retrospective study was conducted from April 2018 to July 2019, and a total of 133 CRKP isolates were collected. Antimicrobial susceptibility was determined by VITEK-2 automated microbiology analyzer platform (bioMérieux, France) and the broth microdilution method. Polymerase chain reaction assays were used to investigate the presence of drug resistance genes. A modified carbapenem inactivation method was performed to detect carbapenemases. Multilocus sequence typing and pulsed-field gel electrophoresis (PFGE) were conducted for genetic relatedness of 50 CRKP isolates selected. <b><i>Results:</i></b> Among 670 isolates of <i>K. pneumoniae</i>, 133 (19.9%) strains were identified as CRKP, of which, 76.7% (102/133) strains were isolated from intensive care units (ICUs). All the 133 CRKP isolates were found to be carbapenemase-producers and harbor bla<i>KPC-2</i> gene. No other carbapenemase genes of <i>blaNDM</i>, <i>blaOXA-48</i>, <i>blaVIM</i>, and <i>blaIMP</i> were detected. Furthermore, β-lactamase genes of <i>blaSHV</i>, <i>blaCTX</i>, and <i>blaTEM</i> were the most common resistance-associated genes among these <i>KPC-2</i> producing isolates. All the 133 CRKP strains displayed >95% of resistance to cephalosporins and carbapenems, except for gentamicin, trimethoprim-sulfamethoxazole, amikacin, tigecycline and colistin, and ceftazidime-avibactam. The most common sequence type was ST11, accounting for 90.0% of the 50 CRKP selected, followed by ST15 (10.0%). PFGE analysis clustered the 50 <i>KPC-2-</i>producing isolates into seven (A-G) distinct clonal clusters at 85% cutoff. Of which, A and G were the two major clusters, accounting for the majority of the strains collected in emergency ICU and neurosurgical ICU. And all the strains of clusters D and E were collected in cardiothoracic surgery ICU, except for one strain collected in one outpatient. <b><i>Conclusion:</i></b> The <i>KPC-2</i>-producing <i>K. pneumoniae</i> belonged to ST11 was widely disseminated in ICUs, and active and effective surveillance of infection control strategies was initiated to limit the spread of CRKP strains.