2.1.4. Multilocus Sequence Typing (MLST)

Kitchen A, as a representative kitchen, was selected to investigate the transmission of C. jejuni during chicken carcass handling. In total, 57 C. jejuni isolates were identified from chicken and food contact surfaces in kitchen A. Multilocus sequence typing (MLST) was performed on all isolates from kitchen A to investigate the contamination route of Campylobacter. The MLST analysis was conducted according to a previous report [28]. Briefly, PCR amplification of seven housekeeping genes aspA, glnA, gltA, glyA, pgm, tkt, and uncA was conducted according to the guidelines provided on the Campylobacter MLST website (https://pubmlst.org/campylobacter/primers, accessed on 02 July 2020). PCR products were sequenced with an ABI 3730 automated DNA sequencer in both orientations. Sequence types (STs) and allele numbers were assigned using the Campylobacter MLST website (developed by Keith Jolley, University of Oxford; http://pubmlst.org/campylobacter, accessed on 11 August 2020).