Genome Analysis of the Multidrug-Resistant Campylobacter coli BCT3 of the Sequence Type (ST) 872 Isolated from a Pediatric Diarrhea Case

Abstract

Campylobacter jejuni and Campylobacter coli are the two main campylobacter species that cause foodborne campylobacteriosis. Recent studies have reported that Campylobacter spp. are prone to developing resistance to antibiotics commonly used for their treatment, with many C. coli strains identified as multidrug-resistant. This study presents the results of the whole-genome sequencing analysis of the multidrug-resistant C. coli strain BCT3 isolated in Greece from a stool specimen of a pediatric patient presenting with diarrhea. The strain was isolated using selective culture media and, based on antimicrobial susceptibility tests, was found to be resistant to ciprofloxacin, tetracycline, erythromycin, azithromycin, clarithromycin, and doxycycline. To further characterize it, we performed whole-genome sequencing, which identified strain BCT3 as C. coli. Moreover, multilocus sequence typing assigned the BCT3 to the sequence type (ST) 872, belonging to clonal complex ST-828. The presence of multiple virulence genes revealed its pathogenic potential. The detection of antimicrobial resistance genes and mutated alleles was indicative of its resistance to fluoroquinolones, macrolides, and tetracyclines, supporting the observed phenotype. To our knowledge, this is the first reported clinical case of such a multidrug-resistant C. coli strain in Greece.

Keywords: Campylobacter coli; antimicrobial resistance genes; diarrhea; fluoroquinolones; genome; macrolides; multidrug resistance; pediatric; virulence.

Figure 1

Phylogenetic and comparative genomic analyses of Campylobacter coli BCT3. Phylogenetic tree showing the relationship among the C. coli BCT3 and type strains in the TYGS database (A). Circular genome alignment between the C. coli BCT3 strain and the C. coli reference strain FDAARGOS_735 (B). Colored ribbons correspond to different levels of % identity according to BLASTn local alignment (red > 98%, green ≤ 98%, blue ≤ 95%, and orange ≤ 90%).

Figure 2

Genome characteristics of the Campylobacter coli BCT3 strain. Circular genome map of the C. coli BCT3 strain generated using DNAPlotter (A). Tracks from inside to outside represent the GC skew, GC content, and reverse (blue) and forward (red) coding sequences (CDSs). Functional categorization of the protein-encoding genes of the C. coli BCT3 genome assigned to subsystem categories (B).

Figure 3

Minimum spanning tree of clonal complex ST-828 constructed for C. coli BCT3 according to the C. jejuni/C. coli MLST scheme.