Emergence of mobilized colistin resistance-1 in multidrug-resistant Klebsiella pneumoniae and Escherichia coli isolates from the Henan province in China: a multicentre study

Abstract

\n Background\n\nThe increased clinical use of polymyxin led to the emergence of polymyxin-resistant strains, especially those carrying plasmid-borne mobilized colistin resistance (mcr) gene variants. In this study, we aimed to evaluate the prevalence and characteristics of polymyxin-resistant Klebsiella pneumoniae and Escherichia coli isolates from the Henan province, China.\nMethods\n\nA total of 16 polymyxin-resistant isolates among 2301 E. coli and K. pneumoniae isolates collected in 6 local hospitals in the Henan province were studied. The isolates were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and the minimum inhibitory concentrations (MICs) were determined using the microbroth dilution technique. Polymyxin-resistant isolates were further analysed for mcr-1 and carbapenemase-mediated resistance using the modified carbapenem inactivation method, the ethylenediaminetetraacetic acid-modified carbapenem inactivation method, and polymerase chain reaction. Pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) were performed to disclose the phylogenetic relationships of the polymyxin-resistant isolates. The clinical characteristics of patients infected with the polymyxin-resistant isolates were also retrospectively analysed.\nResults\n\n5/1499 (0.3%) and 11/802 (1.4%) E. coli and K. pneumoniae isolates, respectively, were polymyxin-resistant. The MICs of polymyxin were in the range of 4–64 µg/mL and all of the 16 polymyxin-resistant isolates were susceptible to tigecycline. Additionally, four of the five E. coli polymyxin-resistant isolates were mcr-1 positive; one of them was also carbapenem-resistant, carrying blaNDM−5. Conversely, only 1/11 K. pneumoniae isolates was mcr-1 positive, while 9 polymyxin-resistant isolates were also carbapenem-resistant (PRCRKP), carrying blaKPC−2 but not mcr-1. MLST results showed that the five E. coli isolates belonged to four sequence types (STs), including ST2, ST132, ST632, and ST983, while all PRCRKP isolates belonged to ST11. However, all 16 isolates showed different PFGE types using a genetic similarity of ≥\u200995%. Furthermore, 33.3% (5/15) of the patients carrying polymyxin-resistant K. pneumoniae isolates showed a history of polymyxin use, and 10/15 (66.7%) patients displayed good clinical outcomes.\nConclusion\n\nThe polymyxin resistance rate of K. pneumoniae was slightly higher than that of E. coli in the Henan province; however, mcr-1 was only detected in one K. pneumoniae isolate. Thus, close monitoring is needed to prevent and control the spread of PRCRKP.