Effect of Stress-Adaptation on Antibiotic Sensitivity Profiles of Campylobacter jejuni

Campylobacter jejuni is one of the leading causes of human gastroenteritis. Campylobacter jejuni requires special conditions and media in the laboratory for its growth. In nature, however, this organism is able to survive in very diverse and hostile environments and produce disease in humans and animals. The different mechanisms by which C. jejuni survives stressful conditions in the environment still remain unclear. Stress-adaptation may be one of the factors helping this organism to survive stresses. Some C. jejuni strains have been found to have increased antibiotic resistance in last several years. To determine the effect of acid adaptation on the antibiotic sensitivity profile of C. jejuni, 4 different isolates of C. jejuni (a human isolate and 3 poultry isolates) were exposed to an acid pH of 5.5 and then re-challenged with different stresses. The antibiotic sensitivity profiles of C. jejuni after stress-adaptation were compared with antibiotic sensitivity profiles of non-stressed C. jejuni using the Kirby Bauer agar disc diffusion assay. The antibiotic sensitivity profiles of the C. jejuni isolates used in this study were found to change when the acid-adapted bacteria were subjected to further stresses such as an acidic pH of 4.5, aerobic atmosphere and starvation. In the majority of the cases, antibiotic-resistant C. jejuni isolates were found to be more sensitive to antibiotics after stress-adaptation, but in a few cases C. jejuni showed increased resistance. These results indicate that increasing various stresses in a sequential pattern may, in some cases, reduce antibiotic resistance of C. jejuni isolates.