|Miller, William - Bill|
Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2009
Publication Date: N/A
Interpretive Summary: Campylobacter spp. are major causes of human food-borne illness. Generally, the species most often associated with food-borne illnesses is Campylobacter jejuni, which is often transmitted through consumption of undercooked or improperly handled chicken meat. However, in this study the most prevalent species identified from chickens was C. coli, a species typically associated with swine. These strains were typed using both biochemical tests and three different molecular typing methods: multilocus sequence typing (MLST), pulsed field gel electrophoresis (PFGE) and flagellinA-restriction fragment length polymorphism analysis (flaA-RFLP). Biochemical tests misidentified several isolates and were unsatisfactory for strain identification, when compared to the molecular methods. The three molecular methods gave similar results, provided the parameters used in the analyses were set properly. MLST analyses further indicated that alleles described earlier in chicken C. coli strains were present also in the strains isolated in this study.
Technical Abstract: To speciate Campylobacter strains from the ceca of chickens in Grenada by PCR and to evaluate DNA-based typing methods for the characterization of these isolates. Isolates were speciated with two multiplex PCR assays and were typed with flaA-RFLP, PFGE and MLST. Results confirmed that C. coli strains were more predominant than C. jejuni strains. From 56 isolates, 18 were misidentified using biochemical tests. PFGE typing gave the highest discriminatory power among the methods used (Simpson’s index of diversity, D = 0.9061). However, the combination of flaA-RFLP, PFGE and MLST results gave the highest discrimination for subtyping of these isolates (D = 0.9857). A band position tolerance of 4% in BioNumerics was the most appropriate for the analysis of this database. MLST profiles were generally concordant with PFGE and/or flaA-RFLP types. Several isolates exhibited new MLST sequence types, and 43 of the 49 C. coli strains belonged to the ST-828 clonal complex. No alleles previously associated with cattle or swine were identified in this study. Biochemical tests may result in the misidentification of C. jejuni and C. coli isolates, and a combination of typing methods appears to be necessary for molecular epidemiology studies of C. coli. Further studies to understand the predominance of C. coli within Campylobacter spp. from chickens in Grenada may help elucidate the epidemiology of these pathogens in chickens.