Fate and Survival of Campylobacter coli in Swine Manure at Various Temperatures

Campylobacter coli is the most common Campylobacter species found in pig (95%), but the ability of this bacterium to survive in swine manure as well as the potential for causing human illness are poorly understood. We present here laboratory-scale experiments to investigate the effect of temperature on the survival of C. coli in spiked swine manure samples at temperatures from 4 to 52°C. The survival of C. coli during storage for 30 days was studied by three different methods: bacterial culture (plate counting), DNA qPCR, and mRNA RT-qPCR. The results indicate that C. coli could survive in swine manure up to 24 days at 4°C. At higher temperatures, this bacterium survived only 7 days (15°C) or 6 days (22°C) of storage. The survival of C. coli was extremely short (few hours) in samples incubated at 42 and 52°C. The results from the RT-qPCR method were consistent with the data from the bacterial culture method, indicating that it detected only viable C. coli cells, thus eliminating false-positive resulting from DNA from dead C. coli cells

Effect of environmental stress factors on the uptake and survival of Campylobacter jejuni in Acanthamoeba castellanii

<p>Abstract</p> <p>Background</p> <p><it>Campylobacter jejuni</it> is a major cause of bacterial food-borne illness in Europe and North America. The mechanisms allowing survival in the environment and transmission to new hosts are not well understood. Environmental free-living protozoa may facilitate both processes. Pre-exposure to heat, starvation, oxidative or osmotic stresses encountered in the environment may affect the subsequent interaction of <it>C. jejuni</it> with free-living protozoa. To test this hypothesis, we examined the impact of environmental stress on expression of virulence-associated genes (<it>ciaB, dnaJ,</it> and <it>htrA</it>) of <it>C. jejuni</it> and on its uptake by and intracellular survival within <it>Acanthamoeba castellanii</it>.</p> <p>Results</p> <p>Heat, starvation and osmotic stress reduced the survival of <it>C. jejuni</it> significantly, whereas oxidative stress had no effect. Quantitative RT-PCR experiments showed that the transcription of virulence genes was slightly up-regulated under heat and oxidative stresses but down-regulated under starvation and osmotic stresses, the <it>htrA</it> gene showing the largest down-regulation in response to osmotic stress. Pre-exposure of bacteria to low nutrient or osmotic stress reduced bacterial uptake by amoeba, but no effect of heat or oxidative stress was observed. Finally, <it>C. jejuni</it> rapidly lost viability within amoeba cells and pre-exposure to oxidative stress had no significant effect on intracellular survival. However, the numbers of intracellular bacteria recovered 5 h post-gentamicin treatment were lower with starved, heat treated or osmotically stressed bacteria than with control bacteria. Also, while ~1.5 × 10³ colony forming unit/ml internalized bacteria could typically be recovered 24 h post-gentamicin treatment with control bacteria, no starved, heat treated or osmotically stressed bacteria could be recovered at this time point. Overall, pre-exposure of <it>C. jejuni</it> to environmental stresses did not promote intracellular survival in <it>A. castellanii</it>.</p> <p>Conclusions</p> <p>Together, these findings suggest that the stress response in <it>C. jejuni</it> and its interaction with <it>A. castellanii</it> are complex and multifactorial, but that pre-exposure to various stresses does not prime <it>C. jejuni</it> for survival within <it>A. castellanii</it>.</p