Abstract
This research aimed to investigate the presence and transferability of the extended-spectrum β-lactamase resistance genes to identify the genetic context of multi-drug resistant (MDR) loci in two Escherichia coli plasmids from livestock and poultry breeding environment. MICs were determined by broth microdilution. A total of 137 E. coli resistant to extended-spectrum β-lactam antibiotics were screened for the presence of the ESBL genes by PCR. Only two E. coli out of 206 strains produced carbapenemases, including strain 11011 that produced enzyme A, and strain 417957 that produced enzyme B. The genes were blaKPC and blaNDM, respectively. The plasmids containing blaCTX–M were conjugatable, and the plasmids containing carbapenem resistance gene were not conjugatable. Six extended-spectrum β-lactamase resistance genes were detected in this research, including blaTEM, blaCTX–M, blaSHV, blaOAX–1, blaKPC, and blaNDM, and the detection rates were 94.89% (130/137), 92.7% (127/137), 24.81% (34/137), 20.43% (28/137), 0.72% (1/137), and 0.72% (1/137), respectively. Two conjugative lncFII multi-resistance plasmids carrying blaCTX–M, p11011-fosA and p417957-CTXM, were sequenced and analyzed. Both conjugative plasmids were larger than 100 kb and contained three accessory modules, including MDR region. The MDR region of the two plasmids contained many antibiotic resistance genes, including blaCTX–M, mph (A), dfrA17, aadA5, sul1, etc. After transfer, both the transconjugants displayed elevated MICs of the respective antimicrobial agents. A large number of resistance genes clusters in specific regions may contribute to the MDR profile of the strains. The presence of mobile genetic elements at the boundaries can possibly facilitate transfer among Enterobacteriaceae through inter-replicon gene transfer. Our study provides beta-lactam resistance profile of bacteria, reveals the prevalence of β-lactamase resistance genes in livestock and poultry breeding environment in Zhejiang Province, and enriches the research on IncFII plasmids containing blaCTX–M.
Highlights
Escherichia coli is the most common conditional pathogen in the culture environment, which can cause varying degrees of infection in livestock and poultry
Class 1 integrons are the most frequently identified integron classes within clinical environments. This class was the first integron found, which mainly distributed on plasmids of Gram-negative bacteria (Goldstein et al, 2001). blaCTX−M gene was used as a query for BLAST search in the NCBI nucleotide sequence database, and it was found that it existed mainly in Enterobacterales
The results showed that six extended-spectrum β-Lactamase resistance genes were detected in all antibiotic resistant strains, including blaTEM, blaCTX−M, blaSHV, blaOAX−1, blaKPC, and blaNDM
Summary
Escherichia coli is the most common conditional pathogen in the culture environment, which can cause varying degrees of infection in livestock and poultry These Escherichia coli strains, which contain a large number of antibiotic resistant genes, accumulate in humans and farmed animals, and are released into the environment via feces. Class 1 integrons are the most frequently identified integron classes within clinical environments This class was the first integron found, which mainly distributed on plasmids of Gram-negative bacteria (Goldstein et al, 2001). BlaCTX−M gene was used as a query for BLAST search in the NCBI nucleotide sequence database, and it was found that it existed mainly in Enterobacterales It is still unknown how frequently the gene occurs in the E. coli in Zhejiang Province, and the number of related IncFII plasmids containing blaCTX−M is not very high in the NCBI database. The genetic background of blaCTX−M needs to be further studied
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