Detection of cytolethal distending toxin (cdt) Genes in Campylobacter jejuni and Campylobacter coli isolated from the intestinal of commercial broiler chickens, turkey and quail of Iran

Abstract

Background: <em>Campylobacter jejuni</em> and <em>Campylobacter coli</em> are zoonotic bacteria which are frequently associated with human diarrhea. Sharing of the cytolethal distending toxin (<em>cdt</em>) genes in Campylobacter is common and is considered species specific. OBJECTIVES: In this study we focused on detecting the presence of <em>cdt</em> gene in <em>C. jejuni</em> and <em>C. coli</em> isolated from broilers, turkeys and quails of Iran. METHODS: Cecal samples were randomly collected from 240 broiler chickens, 100 meat type turkeys and 100 quails after slaughtering. We used PCR as a method for detecting <em>cdt</em> genes. RESULTS: In broilers, 93% of 58 <em>C. jejuni</em> positive samples possessed <em>cdt</em> gene and in all cases the three different subunits of <em>cdt</em> genes were present. However, only 56% of 14 <em>C. coli</em> isolates in broilers had contained <em>cdt</em> genes, while one fourth having all three subunits present. In turkeys, around 65% of 34 <em>C. jejuni</em> positive samples had <em>cdt</em> gene present with 38% possessing all three subunits of <em>cdt</em> genes. But all 5 <em>C. coli</em> isolates had all three subunits <em>cdt</em> gene. In quails, 67% of 30 <em>C. jejuni</em> positive samples were identified by <em>cdt</em> gene, 20% of those possessed all three gene subunits. On the other hand, all 28 <em>C. coli</em> isolates of quails had <em>cdt</em> gene present while 36% of those held all three gene subunits. CONCLUSIONS: Our data is indicating the isolation, culture and <em>cdt</em> PCR amplification approaches in this study seemed to be efficient. However, the presence of different variation of Campylobacter <em>cdt</em> gene types in our sample isolates signifies the necessity of further functional gene studies to elucidate which gene type combinations result in encoding effective toxins. <br />