Whole genome sequencing of a porcine multiresistant Campylobacter coli strain carrying both optrA and cfrC

Abstract:

[Background] Campylobacter is a common group of foodborne pathogens that can cause gastroenteritis in the world. It is increasingly resistant to clinically important antibiotics and poses a serious threat to food safety and public health. [Objective] To investigate the resistance phenotype and genes of a Campylobacter coli strain carrying both optrA and cfrC, the whole genome characteristics of the strain, the distribution of virulence genes, and the gene environments of optrA and cfrC. [Methods] Agar dilution method was employed to determine the minimal inhibitory concentrations (MIC). Whole genome sequencing (WGS) was carried out to sequence the DNA of the strain. [Results] The strain was highly resistant to tetracycline, clindamycin, azithromycin, florfenicol, and linezolid, and sensitive to ciprofloxacin and gentamicin. WGS identified a circular DNA with a size of 1 436 486 bp (GC content of 31.63%), which carried 12 resistance genes involving four major categories of antibiotics. All of the 12 genes were detected on the chromosome, most of which were aminoglycoside resistance genes. A total of 83 virulence genes involved in adherence, invasion and motility were identified, and most of them were associated with motility. The gene islands GIs002 and GIs003 contained resistance genes. CfrC was located on the GIs002, linked with aph(3')-Ⅲa and flanked by two transposons. OptrA was located on chromosome and connected to the insertion sequence Integrase/IS607 family at upstream and downstream sides. Transposon and insertion sequence could mediate the horizontal transfer of resistance genes. [Conclusion] The genome information, resistance genes, and virulence genes of a multiresistant C. coli strain were analyzed by WGS. The mobile genetic elements (transposase and insertion sequence) played an important role in the transmission of antibiotic resistance of C. coli. The findings provide basic information for risk assessment of antibiotic resistance of Campylobacter.