Whole-genome comparative analysis of Campylobacter jejuni strains isolated from patients with diarrhea in northeastern Poland

Abstract

Background: Campylobacter jejuni is the leading cause of bacterial gastroenteritis (campylobacteriosis) in humans worldwide, and the most frequent pathogen associated with Guillain-Barré syndrome (GBS) and Miller-Fisher syndrome (MFS). The study was designed in order to assess similarities between genomes of Campylobacter jejuni strains, isolated from children suffering from acute diarrhea in northeastern Poland, in comparison to C. jejuni genomes stored in public databases. The analysis involved phylogeny, resistome and virulome. In addition, the Campylobacter PubMLST database was used to estimate the prevalence of the analyzed C. jejuni sequence type (STs) in other countries.

Results: Campylobacter jejuni ST50, ST257 and ST51 represented 5.3%, 4.5% and 2.2% of the PubMLST records, respectively. Overall, strains representing the STs showed common resistance to tetracyclines (51.3%) and fluoroquinolones (31.8%), mediated through the tetO gene (98.2%) and point mutation (T86I) in the gyrA gene (100%). However, the latter was present in all our isolates. The major differences in virulence patterns concerned serotypes, lipooligosaccharide (LOS) classes and certain clinically relevant genes.

Conclusions: Campylobacter jejuni ST50, ST51 and ST257 are among the top ten of STs isolated in Europe. WGS revealed diversity of serotypes and LOS classes in ST50 strains, that deserves further clinical and epidemiological investigations as it might be related to a risk of post-infectious neurological sequels such as Guillain-Barré syndrome. Additionally, the results implicate lower pathogenic potential and distinct transmission chains or reservoirs for C. jejuni ST51 isolates responsible for campylobacteriosis in northeastern Poland.

Keywords: Antibiotic resistance; Campylobacteriosis; MLST; Virulence; WGS.

Fig. 1

Phylogenetic tree of C. jejuni ST50, ST51 and ST257 constructed based on core genes comparison using Roary and RAxML software. Black, blue and green colors of the tree branches indicate ST50, ST51 and ST257 strains, respectively. The isolates from northeastern Poland are in red

Fig. 2

Dendrogram representing similarity of virulence patterns of C. jejuni ST50, ST51 and ST257 strains. The dendrogram was constructed based on presence/absence of virulence genes (n = 143) using UPGMA method and Dice coefficient in NTSYS-pc software. Black, blue and green colors of the tree branches indicate ST50, ST51 and ST257 strains, respectively. The isolates from northeastern Poland are shown in red