First report of the optrA-carrying multidrug resistance genomic island in Campylobacter jejuni isolated from pigeon meat

Campylobacter spp., such as Campylobacter jejuni and Campylobacter coli, are important zoonotic Gram-negative pathogens that cause acute intestinal diseases in humans. The optrA gene, encoding an ATP-binding cassette F (ABC-F) protein that confers resistance to oxazolidinones and phenicols, has been found in C. coli in China. In this study, the optrA gene was first identified in C. jejuni collected from retail meat in China from 2013 to 2016. Nine strains, isolated from a pigeon meat sample, carry the optrA gene. The molecular characteristics of the optrA-positive strains were determined by whole genome sequencing. Pulsed-field gel electrophoresis, multilocus sequence typing, and single nucleotide polymorphism analyses demonstrated that the nine optrA-positive isolates were genetically homogeneous. Phylogenetic characteristics and sequence comparison revealed that optrA was located on a chromosome-borne multidrug resistance genomic island. The optrA gene along with the tet(O) gene formed two different translocatable units (TUs), thereby supporting the transmission of TU-associated resistance genes. The emergence and spread of such TUs and strains are of great concern in terms of food safety, and measures must be implemented to avoid their dissemination in other Gram-negative bacteria and food chains. •Nine linezolid and florfenicol resistance Campylobacter jejuni were isolated.•All strains were optrA positive and belonged to ST9560.•The chromosome-borne optrA gene were located within a 21,333 bp MDRGI.•Two transposition units were formed via the IS1216E and tet(O).