Research Note: Antimicrobial resistance of Campylobacter species isolated from chickens near Ulaanbaatar city, Mongolia

Abstract

There has been no report on the prevalence of Campylobacter spp. in farm animals in Mongolia. To uncover the prevalence of Campylobacter spp. in chickens in Mongolia and their antimicrobial resistance, in this study, we isolated and characterized Campylobacter spp. from chickens in Mongolia. We collected 71 cloacal swabs of chickens from 5 farms including 4 layer farms and one broiler farm near Ulaanbaatar city and isolated 25 Campylobacter jejuni and 6 Campylobacter coli isolates. All isolates were resistant to tetracycline, and 3 C. coli isolates were resistant to erythromycin. The C. coli isolates possessed either the erm(B) gene or nucleotide substitution at nt 2,075 of 23S rDNA, both of which are known to be associated with erythromycin resistance. Sixteen of the 31 C. jejuni/C. coli isolates (51.6%) were resistant to nalidixic acid and fluoroquinolones. All the fluoroquinolone-resistant isolates possessed amino acid substitution from threonine to isoleucine at codon 86 (nucleotide substitution: ACA to ATA). Multilocus sequence typing and phylogenetic analyses showed a variation in C. jejuni/C. coli in chickens in Mongolia. In addition, some of the C. jejuni isolates seemed to be phylogenetically close to isolates in Asian and Oceanian countries. This is the first report on the characterization of antimicrobial resistance of Campylobacter spp. in farm animals in Mongolia and is valuable for implementation of measures for a prudent use of antimicrobials in farm animals.

Keywords: Campylobacter; Mongolia; antimicrobial resistance; fluoroquinolone.

Figure 1

Phylogenetic analysis of C. jejuni and C. coli isolated from chickens in Mongolia. Nucleotide sequences of a total of 3,024 nt from aspA, glnA, gltA, glyA, tkt, uncA, and pgm were used for phylogenetic analysis. Nucleotide sequences of ST22 (CC22), ST487 (CC21), ST847 (CC21), ST2956 (CC21), ST2787 (CC21), ST3156 (CC21), ST4258 (CC: unassigned [UA]), ST6077 (CC: UA), ST7357 (CC574), and ST8017 (CC574) for C. jejuni and of ST872 (CC828), ST989 (CC828), and ST3753 (CC828) for C. coli were obtained from the Campylobacter Sequence Typing database. The percentages (>50%) of replicate trees in which the associated taxa clustered together in the bootstrap test (1,000 replicates) are shown italic numbers next to the branches.