Genetic diversity of Campylobacter sp. isolates from retail chicken products and humans with gastroenteritis in Central Michigan

Multilocus sequencing was used to compare Campylobacter sp. strains isolated from retail chicken products and humans with gastroenteritis in central Michigan. Sequence comparisons demonstrated overlapping diversity between chicken and human isolates. Campylobacter jejuni isolates from clinical sources had a greater diversity of flagellin alleles and a higher rate of quinolone resistance than isolates from retail chicken products.

Variation of the natural transformation frequency of Campylobacter jejuni in liquid shake culture

Natural transformation, a mechanism that generates genetic diversity in Campylobacter jejuni, was studied in a novel liquid shake culturing system that allowed an approximately 10 000-fold increase in cell density. C. jejuni transformation frequency was analysed in this system under 10 %, 5·0 % and 0·7 % CO2 atmospheres. At 5·0 % and 10 % CO2 concentrations, when purified isogenic chromosomal DNA was used to assess competence, transformation frequency ranged from 10−3 to 10−4 at low cell concentrations and declined as cell density increased. Transformation frequency under a 0·7 % CO2 atmosphere was more stable, maintaining 10−3 levels at high cell densities, and was 10- to 100-fold higher than that under a 10 % CO2 atmosphere. Three of four C. jejuni strains tested under a 5·0 % CO2 atmosphere were naturally competent for isogenic DNA; competent strains demonstrated a lack of barriers to intraspecies genetic exchange by taking up and incorporating chromosomal DNA from multiple C. jejuni donors. C. jejuni showed a preference for its own DNA at the species level, and co-cultivation demonstrated that DNA transfer via natural transformation occurred between isogenic populations during short periods of exposure in liquid medium when cell density and presumably DNA concentrations were low. Transformation frequency during co-cultivation of isogenic populations was also influenced by CO2 concentration. Under a 0·7 % CO2 atmosphere, co-cultivation transformation frequency increased approximately 500-fold in a linear fashion with regard to cell density, and was 1000- to 10 000-fold higher during late-exponential-phase growth when compared to cultures grown under a 10 % CO2 atmosphere.

Enhancement of disease and pathology by synergy of Trichuris suis and Campylobacter jejuni in the colon of immunologically naive swine

Campylobacterjejuni, a leading cause of bacterial gastroenteritis, has different age distribution and disease expression in developing and developed countries, which may be due to the endemnicity of infection and the age of acquisition of immunity. Differences in disease expression are not solely dependent on the C. jejuni strain or virulence attributes. Another modulating factor in developing countries may be endemic nematode infections such as Trichuris, which drive type 2 cytokine responses and down-regulate type 1 immune responses. In this study, three-day-old germ-free pigs given dual infections with Trichuris suis and C. jejuni had more frequent, more severe diarrhea and severe pathology than pigs given no pathogens, only T. suis, or only C. jejuni. These pigs had significant hemorrhage and inflammatory cell infiltrates in the proximal colon where adult worms were found, and abscessed lymphoglandular complexes in the distal colon with intracellular C. jejuni. Pigs given only C. jejuni had mild clinical signs and pathology, and bacteria in feces or extracellular sites. Pigs given T. suis or no pathogens had no disease and minimal pathology. Thus, these agents synergized to produce significant disease and pathology, which was site specific.

Enhancement of disease and pathology by synergy of Trichuris suis and Campylobacter jejuni in the colon of immunologically naive swine

Campylobacter jejuni, a leading cause of bacterial gastroenteritis, has different age distribution and disease expression in developing and developed countries, which may be due to the endemnicity of infection and the age of acquisition of immunity. Differences in disease expression are not solely dependent on the C jejuni strain or virulence attributes. Another modulating factor in developing countries may be endemic nematode infections such as Trichuris, which drive type 2 cytokine responses and down-regulate type 1 immune responses. In this study, three-day-old germ-free pigs given dual infections with Trichuris suis and C jejuni had more frequent, more severe diarrhea and severe pathology than pigs given no pathogens, only T. suis, or only C jejuni. These pigs had significant hemorrhage and inflammatory cell infiltrates in the proximal colon where adult worms were found, and abscessed lymphoglandular complexes in the distal colon with intracellular C jejuni. Pigs given only C jejuni had mild clinical signs and pathology, and bacteria in feces or extracellular sites. Pigs given T. suis or no pathogens had no disease and minimal pathology. Thus, these agents synergized to produce significant disease and pathology, which was site specific.