Abstract
Yokenella regensburgei, a member of the family Enterobacteriaceae, is usually isolated from environmental samples and generally resistant to early generations of cephalosporins. To characterize the resistance mechanism of Y. regensburgei strain W13 isolated from the sewage of an animal farm, whole genome sequencing, comparative genomics analysis and molecular cloning were performed. The results showed that a novel chromosomally encoded class C β-lactamase gene with the ability to confer resistance to β-lactam antibiotics, designated blaYOC–1, was identified in the genome of Y. regensburgei W13. Kinetic analysis revealed that the β-lactamase YOC-1 has a broad spectrum of substrates, including penicillins, cefazolin, cefoxitin and cefotaxime. The two functionally characterized β-lactamases with the highest amino acid identities to YOC-1 were CDA-1 (71.69%) and CMY-2 (70.65%). The genetic context of the blaYOC–1-ampR-encoding region was unique compared with the sequences in the NCBI nucleotide database. The plasmid pRYW13-125 of Y. regensburgei W13 harbored 11 resistance genes (blaOXA–10, blaLAP–2, dfrA14, tetA, tetR, cmlA5, floR, sul2, ant(3″)-IIa, arr-2 and qnrS1) within an ∼34 kb multidrug resistance region; these genes were all related to mobile genetic elements. The multidrug resistance region of pYRW13-125 shared the highest identities with those of two plasmids from clinical Klebsiella pneumoniae isolates, indicating the possibility of horizontal transfer of these resistance genes between bacteria of various origins.
Highlights
Yokenella regensburgei is a species of Enterobacteriaceae originally identified by Kosako et al (1984) through DNA hybridization and biochemical tests in 1984
It has been hypothesized that infections caused by Y. regensburgei were underestimated due to misidentification of the bacterium (Bhowmick and Weinstein, 2013)
The average nucleotide identity (ANI) analysis results revealed that W13 shared high identity (99.05%) with Yokenella regensburgei ATCC 43003 (NZ_AGCL00000000), and this isolate was designated Y. regensburgei W13
Summary
Yokenella regensburgei is a species of Enterobacteriaceae originally identified by Kosako et al (1984) through DNA hybridization and biochemical tests in 1984. In 1985, HickmanBrenner et al (1985) proposed the name Koserella trabulsii for a new group of Enterobacteriaceae they had discovered that was previously called Enteric Group 45. It was subsequently hown by DNA hybridization that Y. regensburgei and K. trabulsii were the same species (Kosako et al, 1987). Y. regensburgei has been found in a variety of environmental samples (Jain et al, 2013; Chi et al, 2017) This organism has been sporadically isolated from clinical samples, demonstrating its ability to act as an opportunistic pathogen (Abbott and Janda, 1994; Bhowmick and Weinstein, 2013; Jain et al, 2013; Chi et al, 2017; Palmisano et al, 2019; Wright et al, 2019). It has been hypothesized that infections caused by Y. regensburgei were underestimated due to misidentification of the bacterium (Bhowmick and Weinstein, 2013)
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