Carvacrol attenuates Campylobacter jejuni colonization factors and proteome critical for persistence in the chicken gut.

ABSTRACT Campylobacter jejuni is a major foodborne pathogen that causes gastroenteritis in humans. Chickens act as the reservoir host for C. jejuni, wherein the pathogen asymptomatically colonizes the ceca leading to contamination of carcasses during slaughter. The major colonization factors in C. jejuni include motility, intestinal epithelial attachment, acid/bile tolerance, and quorum sensing. Reducing the expression of the aforementioned factors could potentially reduce C. jejuni colonization in chickens. This study investigated the efficacy of sub-inhibitory concentration (SIC; compound concentration not inhibiting bacterial growth) of carvacrol in reducing the expression of C. jejuni colonization factors in vitro. Moreover, the effect of carvacrol on the expression of C. jejuni proteome was investigated using liquid chromatography tandem mass spectrometry (LC-MS/MS). The motility assay was conducted at 42°C, and the motility zone was measured after 24 h of incubation. For the adhesion assay, monolayers of primary chicken enterocytes (∼105 cells/well) were inoculated with C. jejuni (6 Log CFU/well) either in the presence or absence of carvacrol and the adhered C. jejuni were enumerated after 90 min of incubation at 42°C. The effect of carvacrol on C. jejuni quorum sensing and susceptibility to acid/bile stress was investigated using a bioluminescence and an acid-bile survival assay, respectively. The SIC (0.002%) of carvacrol reduced the motility of C. jejuni strains S-8 and NCTC 81-176 by ∼50% and 35%, respectively (P