Emergence of a Clinical Escherichia coli Sequence Type 131 Strain Carrying a Chromosomal bla KPC-2 Gene.

Dairong Wang,Ying Chen,Jingjing Quan,Xi Li,Guofeng Mao,Xinli Mu,Dongdong Zhao,Ying Fu,Yiwei Zhu,Xiaoting Hua,Yan Jiang,Yunsong Yu

doi:10.3389/fmicb.2020.586764

Abstract

Objectives: Bacteria carrying the Klebsiella pneumoniae carbapenemase genes have rapidly spread worldwide and have become a great threat to public health. The blaKPC–2 gene has been primarily located on plasmids cocirculating in various strains. However, chromosomal integration of the blaKPC–2 gene in Escherichia coli has not been reported. In the present study, we report the detection of the first clinical strain of E. coli ST131 with a blaKPC–2 gene, which integrated in the chromosome. E. coli strain EC3385 was identified and subjected to susceptibility testing and genotyping. The complete genome sequences of this strain and four Proteus mirabilis strains were obtained. Chromosomal integration of the blaKPC–2 gene was confirmed using a combination of short- and long-read sequencing. Comparative genetic analyses were performed and the origin of the chromosomal location of the blaKPC–2 gene was further analyzed. Whole-genome sequencing revealed that strain EC3385 belonged to the ST131 type and possessed various resistance and virulence genes. Sequence analysis showed that the blaKPC–2 gene was carried in a 24-kb insertion sequence on the chromosome. This insertion sequence possessed high sequence similarity to previously reported blaKPC–2-habouring plasmids of P. mirabilis in China. To the best of our knowledge, this is the first report of a clinical ST131 E. coli strain carrying blaKPC–2 on the chromosome. The blaKPC–2 gene was probably horizontally transferred from the P. mirabilis plasmid to the E. coli chromosome by the IS26 element, indicating that P. mirabilis might be an important reservoir of blaKPC–2 gene for E. coli. Furthermore, the E. coli ST131 strain carrying the chromosomal blaKPC–2 gene could be further spread due to its carbapenem resistance and high virulence. It is imperative to perform active surveillance to prevent further dissemination of KPC-2 type carbapenemase-producing isolates.

Highlights

Bacteria carrying the Klebsiella pneumoniae carbapenemase genes have rapidly spread worldwide and have become a great threat to public health because these bacteria are often associated with high morbidity and mortality (Wang et al, 2016; An et al, 2018)
The antimicrobial susceptibility test results showed that E. coli strain EC3385 was resistant to multiple antimicrobial agents, including cephalosporins, carbapenems and fluoroquinolones, but it was susceptible to aminoglycosides, ceftazidime-avibactam, colistin, and tigecycline (Table 1)
The ST131-type E. coli clonal group emerged in the mid-2000s and has since spread extensively throughout the world (Can et al, 2015)

Summary

Introduction

Bacteria carrying the Klebsiella pneumoniae carbapenemase genes (blaKPC) have rapidly spread worldwide and have become a great threat to public health because these bacteria are often associated with high morbidity and mortality (Wang et al, 2016; An et al, 2018). In China, clonal spreading is a main mode of transfer of KPC-2 type carbapenemaseproducing K. pneumonia. Unlike K. pneumoniae, clonal spread has not been found for the blaKPC−2 gene of E. coli (Chen et al, 2014). These strains have different clone types, such as ST131, ST410, ST2281, ST43, ST721, ST4385, and ST8 (Kim et al, 2012; Mavroidi et al, 2012; Tian et al, 2020). Among these clone types, E. coli ST131, an international multidrugresistant high-risk clone, has gained a further selective advantage as a result of acquiring carbapenem resistance (Rogers et al, 2011; Kim et al, 2012) and E. coli ST131 may become a successful lineage of KPC-2 type carbapenemase-producing E. coli

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Conclusion