Molecular Characterization and Antibiotic Resistant Profiles of Campylobacter Species Isolated From Poultry and Diarrheal Patients in Southeastern China 2017-2019

Abstract

Campylobacter is a zoonotic pathogen that causes foodborne diarrheal illness globally. To better understand health risks in Southeastern China, Campylobacter spp. were surveyed in humans and representative poultry products over 3 years. One hundred and ninety-five representative isolates (n = 148, Campylobacter jejuni; n = 45, Campylobacter coli; n = 2 Campylobacter hyointestinalis) were examined for genetic relatedness and antimicrobial susceptibility. Nearly all Campylobacter isolates (99.0%, 193/195) were resistant to at least one class of antimicrobials, and 45.6% (89/195) of the isolates exhibited multidrug resistance. Genotypic analysis revealed high diversity among tested strains. Multilocus sequence typing (MLST) displayed 120 sequence types (STs) including 42 novel STs being added to the PubMLST international database. Sixty-two STs belonged to 16 previously characterized clonal complexes (CCs), of which CC-21, CC-45, CC-464, CC-574, CC-353, and CC-828 were most frequently identified. In addition, pulsed-field gel electrophoresis (PFGE) fingerprinting resulted in 66 PFGE SmaI patterns among the 125 isolates, with eight patterns shared between human and poultry sources. Subtyping data did not correlate with antimicrobial resistance phenotypes. Taken together, this large-scale surveillance study highlights high antimicrobial resistance and molecular features of Campylobacter isolates in Southeastern China.

Keywords: Campylobacter; MLST; PFGE; human feces; multidrug resistance; poultry.

FIGURE 1

Clonal distribution analysis of Campylobacter spp. (A) Minimum spanning tree based on MLST data from 193 Campylobacter strains. Sources are distinguished by color differences (chicken, red; duck, blue; diarrheal patient, yellow). Different circles correspond to different STs. Size of circle indicates number of isolates within the same ST, and thickness of the branches represents the degree of similarity among Campylobacter tested. A bold solid line indicates that one allele is different according to the length. Two to three allele differences are represented by a thin solid line, and four is indicated by a wide-interval dotted line. A narrow-interval dotted line shows that there is a five-allele difference between STs. Nodes with fewer than three different alleles have been placed in the same cluster. Most STs in the circle of C. coli are assigned to CC-828, except ST-9625, ST-9440, ST-7263, and ST-1450. Asterisk indicates newly designated ST in this study. (B) Proportion of MLST clonal complexes in each source. UA, unassigned ST.

FIGURE 2

Dendrogram of 80 C. jejuni strains based on SmaI-mediated PFGE profiles. PFGE pattern, strain source, isolation year, sequence type, and clonal complex are depicted. Asterisk indicates newly designated ST in this study. Black squares of the antibiogram indicate resistance to antibiotics.

FIGURE 3

Dendrogram of 45 C. coli strains based on SmaI-mediated PFGE profiles. PFGE pattern, strain source, isolation year, sequence type, and clonal complex are depicted. Asterisk indicates newly designated ST in this study. Black squares in the antibiogram indicate resistance to antibiotics.