Molecular Typing of Campylobacter Species Isolated from Healthy Indigenous Chickens in Grenada

Aim: To identify the sequence types (STs) of Campylobacter from indigenous chickens in Grenada and compare the results to other animals in Grenada and other countries from previous published studies.

Study Design: Thermotolerant Campylobacter spp are the leading cause of human gastroenteritis worldwide. Little is known in Grenada about the dynamics of the epidemiology of Campylobacter in food animals including indigenous chickens.

Methodology: In a previous study, 158 Campylobacter isolates were obtained from cloacal swab samples of 315 randomly selected healthy indigenous chickens in Grenada between May and July 2014. After isolation, the 158 Campylobacter isolates were stored in 10% sterile skim milk solution at -80°C until ready for DNA extraction. DNA was extracted from only 24 viable Campylobacter isolates out of the 158 Campylobacter isolates stored. The extracted DNA samples were shipped on dry ice for multilocus sequence typing (MLST) analysis.

Results: A total of 24 viable Campylobacter isolates (13 C. jejuni and 11 C. coli) were identified by polymerase chain reaction (PCR). Different clonal complexes (CCs) and STs were identified from the 24 Campylobacter isolates with ST-353 identified as the predominant STs from C. jejuni isolates. Most of the previously reported STs in this study belong to ST-828 CC. All the previously reported STs generated from C. jejuni have been associated with human gastroenteritis in different geographical regions. Five novel clones which have not been reported in humans or animals worldwide were identified in this study.

Conclusion: This study showed the importance of indigenous chickens as reservoirs for Campylobacter species that have been associated with human gastroenteritis worldwide. This study also revealed that indigenous chickens in Grenada harbor novel Campylobacter STs that have not been reported in humans and animals worldwide. This is the first report that documents the molecular typing of Campylobacter species and the identification of novel Campylobacter STs from indigenous chickens of Grenada origin.