Clinical Campylobacter jejuni isolates: genomes and genetic tools

Campylobacter jejuni is a major cause of food-borne gastroenteritis and is responsible for substantial mortality and economic losses in meat and dairy production. Detecting C. jejuni in contaminated food samples remains difficult because current assays are culture-based, slow, and can yield false positives. As a result, contamination may not be identified for several days, limiting detection at the point of production. Developing improved assays has also been challenging because Campylobacter genetics and the biology of clinical isolates remain poorly understood. Here, we expand the C. jejuni genetic toolbox by sequencing two strains, HC1 and RM1164, derived from patient and food samples. We identified two cryptic plasmids in HC1, one potentially capable of conjugation and another conferring tetracycline resistance. We also engineered a mobilizable plasmid carrying an OriT sequence that can be transferred from Escherichia coli donor strains to C. jejuni RM1164 by conjugation. Together, these clinical isolates and the plasmid system expand the genetic tools available for C. jejuni.