Genetic Characteristics and Antimicrobial Susceptibility of Arcobacter butzleri Isolates from Raw Chicken Meat and Patients with Diarrhea in China

Arcobacter is an emerging foodborne pathogen worldwide.In this study,the prevalence,antimicrobial susceptibility and genetic characteristics of Arcobacter from different sources were investigated.Eighteen A.butzleri isolates were obtained from 60 raw chicken meat samples(16/60,27%)and 150 patients with diarrhea(2/150,1.3%).The resistance ratios to nalidixic acid,ciprofloxacin,clindamycin,chloramphenicol,and florfenicol were 83.33%(15/18),38.89%(7/18),38.89%(7/18),33.33%(6/18)and 33.33%(6/18),respectively.We performed whole genome sequencing of the 18 isolates,and we predicted antibiotic resistance genes and virulence factors by using assembled genomes through blastx analysis.Two resistance genes,blaOXA-464 and tet(H),and the C254T mutation in gyrA,were identified in the genomes of some resistant isolates.Furthermore,virulence genes,such as flgG,flhA,flhB,fliI,fliP,motA,cadF,cjl349,ciaB,mviN,pldA and tlyA,were found in all strains,whereas hecA,hecB and iroE were found in only some strains.Phylogenetic tree analysis of A.butzleri isolates on the basis of the core-genome single nucleotide polymorphisms showed that two isolates from patients with diarrhea clustered together,separately from the isolates from raw chicken and the chicken strains.This study is the first comprehensive analysis of Arcobacter isolated in Beijing.