Orthogonal typing methods identify genetic diversity among Belgian Campylobacter jejuni strains isolated over a decade from poultry and cases of sporadic human illness

Authors: ELHADIDY, MOHAMED - Mansoura University; ARGUELLO, HECTOR - Universidad De Cordoba; ÁLVAREZ-ORDÓÑEZ, AVELINO - University Of Leon; Miller, William - Bill; DUARTE, ALEXANDRA - Ghent University; MARTINY, DELPHINE - Saint Pierre University Hospital; HALLIN, MARIE - Saint Pierre University Hospital; VANDENBERG, OLIVIER - Saint Pierre University Hospital; DIERICK, KATELIJNE - Scientific Institute Of Public Health; BOTTELDOORN, NADINE - Scientific Institute Of Public Health

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2018
Publication Date: 4/4/2018
Citation: Elhadidy, M., Arguello, H., Álvarez-Ordóñez, A., Miller, W.G., Duarte, A., Martiny, D., Hallin, M., Vandenberg, O., Dierick, K., Botteldoorn, N. 2018. Orthogonal typing methods identify genetic diversity among Belgian Campylobacter jejuni strains isolated over a decade from poultry and cases of sporadic human illness. International Journal of Food Microbiology. 275:66-75. https://doi.org/10.1016/j.ijfoodmicro.2018.04.004.
DOI: https://doi.org/10.1016/j.ijfoodmicro.2018.04.004

Interpretive Summary: The food-borne pathogen Campylobacter is a natural contaminant of most birds and livestock, with poultry meat the major vehicle for Campylobacter-associated illness in humans. This study typed Campylobacter jejuni strains from two different sources (chicken broilers and sporadic cases of human diarrhea), collected over ten years (2006-2015) by three different methods: two DNA sequence-based typing methods (MLST and P-BIT) and analysis of the genes responsible for placing sugars on the outer surface of each cell. The DNA sequence types were both numerous and diverse, with some types not seen previously. Many types were found in both the chicken samples and human clinical samples, consistent with poultry transmission of C. jejuni. Some C. jejuni outer surface sugars can elicit an autoimmune response in humans, leading to disorders like Guillain-Barre syndrome, which causes muscle weakness and paralysis. The majority of isolates in this study contained outer surface sugars that could potentially lead to such secondary disorders. The types determined by one sequence-based method did not correspond to those determined by the other. Nevertheless, either method was highly discriminatory. The data generated from this study will help to address food security and public health challenges resulting from C. jejuni infection.

Technical Abstract: Campylobacter jejuni is a zoonotic pathogen commonly associated with human gastroenteritis. Retail poultry meat is a major food-related transmission source of C. jejuni to humans. The present study investigated the genetic diversity, clonal relationship, and strain risk-ranking of 403 representative C. jejuni isolates from chicken broilers (n=204) and sporadic cases of human diarrhea (n=199) over a decade (2006-2015) in Belgium using multilocus sequence typing (MLST), PCR binary typing (P-BIT), and identification of lipooligosaccharide biosynthesis (LOS) locus classes. A total of 123 distinct sequence types (STs), clustered in 28 clonal complexes (CCs), were assigned, including 10 novel sequence types that were not previously documented in the international database. The ST-48, ST-21, ST-50, ST-45, ST-464, ST-2274, ST-572, ST-19, ST-257, and ST-42 were prevailing. Clonal complex 21 was the main clonal complex in isolates from humans (n= 63) and chickens (n= 50). Among observed STs, a total of 35 STs that represent 72.5% (292/403) of the isolates overlapped in both chicken and human isolates confirming considerable epidemiologic relatedness. These overlapped STs clustered together in the leading CCs. The majority of isolates harbored sialylated LOS with potential neuropathic outcomes in humans. Although the concordance between MLST and binary typing, determined by the adjusted Rand and Wallace coefficients, showed low congruence between both typing methods, the discriminatory power of P-BIT and MLST was similar, with Simpson's diversity indexes of 0.978 and 0.975, respectively. Furthermore, binary typing could provide additional epidemiological information related to individual risk to human health from each strain. In addition, certain clones could be linked to specific clinical symptoms. Indeed, LOS class E was associated with a less severe infections. Moreover, ST-572 and CC-UA were significantly associated with clinical infections occurring after travelling abroad. Ultimately, the data generated from this study will help to address food security and public health challenges resulting from C. jejuni infection.