Chicken as a carrier of emerging virulent Helicobacter species: a potential zoonotic risk

The research scope regarding Helicobacter species in chickens, other than H. pullorum, is largely overlooked. This study aimed to investigate the prevalence of emerging Helicobacter species in chickens and the occurrence of the virulence gene cytolethal distending toxin B (cdtB) among the identified Helicobacter species, referring to their public health significance.

A total of 390 cloacal swabs were collected from 205 broilers and 185 layers. The swabs were pooled into 78 pools. DNA was extracted from these pools, followed by Helicobacter 16S rRNA gene PCR. Twenty pools positive for Helicobacter 16S rRNA were analyzed for H. pylori and H. pullorum, then Helicobacter 16S rRNA sequencing was performed on ten negative pools for H. pullorum and H. pylori to identify Helicobacter species. Subsequently, cdtB was investigated in the 20 pools positive for Helicobacter. Following that, partial DNA sequencing of one H. pullorum and one H. brantae cdtB gene from broiler and layer chickens, respectively, was carried out.

Overall, 25.6% of the examined pools were positive for Helicobacter spp., with 3 (7.3%) and 17 (45.9%) broiler and layer pools being positive, respectively. All three broiler pools were identified as H. pullorum; seven-layer pools were positive for H. pullorum, while H. pylori could not be detected. Helicobacter 16S rRNA sequencing of ten negative layer pools for H. pullorum and H. pylori revealed 6 H. brantae, 2 H. kayseriensis, 1 H. winghamensis, and 1 Helicobacter sp. Tul. The cdtB gene was found in 10 H. pullorum, 5 H. brantae, 1 H. winghamensis, and 1 Helicobacter sp. Tul. Phylogenetic analysis of Helicobacter 16S rRNA sequences and BLAST analysis of H. pullorum and H. brantae cdtB partial sequences underscore the public health importance of the obtained sequences.

This study highlights that the occurrence of emerging virulent Helicobacter species in chicken feces poses a potential zoonotic relevance and public health risk.