engleski

Influence of selected environmental stresses on Campylobacter jejuni virulence

Campylobacters, gram negative spiral shaped, microaerophylic and termophilic bacteria, counter several survival strategies which contribute to their persistence and spreading in the environment. These bacteria cause food-borne illnesses worldwide due to contaminated food and cross-contamination. This is at least partly the consequence of bacterial adaptation to environmental stresses they face in the environment and during food processing. The results are increased survival and virulence properties of these bacteria. Stress has also an impact on increased/reduced sensitivity of the host (intestinal) cells to infection. The aim of our study was to evaluate the effect of environmental stress factors: temperature, starvation and atmospheric oxygen exposure on the ability of C. jejuni to cause systemic infection in experimental animals. BALB/c mice were intravenously injected with stressed campylobacters and at different time points after infection, the number of bacterial CFU in their livers and spleens were determined. At the same time paraffin sections were prepaired for histopathological evaluation. The experiments showed that nutrient insufficiency was the most powerful stress factor. Starvation significantly decreased infectious potential of C. jejuni, seen as the lowest bacterial load in examined organs. Heat shock exposure of C. jejuni also caused modulation of its virulence in vivo, but in a lesser extent than starvation. To the opposite, oxidative stress enhanced C. jejuni virulence according to the highest bacterial load in the livers and spleens of infected mice.

Campylobacter jejuni; stress; virulence; BALB/c mice

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