Survival of Campylobacter jejuni under Conditions of Atmospheric Oxygen Tension with the Support of Pseudomonas spp

Campylobacter jejuni is a major food-borne pathogen. Despite causing enteritis in humans, it is a well-adapted intestinal microorganism in animals, hardly ever generating disease symptoms. Nevertheless, as a true microaerophilic microorganism it is still puzzling howCampylobacter cells can survive on chicken meat, the main source of human infection. In this study, we demonstrate thatC. jejuni is able to withstand conditions of atmospheric oxygen tension when cocultured withPseudomonas species, major food-spoiling bacteria that are frequently found on chicken meat in rather high numbers. Using anin vitro survival assay, interactions of 145C. jejuni wild-type strains and field isolates from chicken meat, broiler feces, and human clinical samples with type strains and food isolates ofPseudomonas spp.,Proteus mirabilis ,Citrobacter freundii ,Micrococcus luteus , andEnterococcus faecalis were studied. When inoculated alone or in coculture withProteus mirabilis ,Citrobacter freundii ,Micrococcus luteus , orEnterococcus faecalis type strains,Campylobacter cells were able to survive ambient oxygen levels for no more than 18 h. In contrast,Campylobacter bacteria inoculated with type strains or wild-type isolates ofPseudomonas showed a prolonged aerobic survival of up to >48 h. This microbial commensalism was diverse inC. jejuni isolates from different sources; isolates from chicken meat and humans in coculture withP seudomonas putida were able to use this survival support better than fecal isolates from broilers. Scanning electron microscopy revealed the development of fiberlike structures braidingP. putida andC. jejuni cells. Hence, it seems that microaerophilicC. jejuni is able to survive ambient atmospheric oxygen tension by metabolic commensalism withPseudomonas spp. This bacterium-bacterium interaction might set the basis for survival ofC. jejuni on chicken meat and thus be the prerequisite step in the pathway toward human infection.