The Gram negative bacterium Salmonella sp. is the most common cause of gastroenteritis in the United States and abroad. Its life cycle... Show moreThe Gram negative bacterium Salmonella sp. is the most common cause of gastroenteritis in the United States and abroad. Its life cycle persists when the bacteria is picked up from the environment and ingested by a host animal. The bacteria adhere to the host’s small intestine and penetrate into the sub-epithelial tissue where it causes diarrhea and vomiting. The bacteria redeposit into the environment via the aforementioned route; thus, repeating the cycle. Salmonella can infect a variety of hosts and different serotypes vary in severity. In addition to the disease causing infections of some host animals such as birds and reptiles provide a reservoir for Salmonella. Reservoir hosts can carry and transmit the bacterium without showing any signs or symptoms of infection. The avian host can pick up the bacteria, by ingestion of contaminated food and water, and deposit it onto the surface or inside the egg. Salmonellosis is then transmitted to human by consumption of contaminated eggs. Salmonella enterica serotype Enteritidis is the most common serotype associated with contaminated chicken eggs. Salmonella Enteritidis inoculated onto the surface of whole chicken eggs was able to survive for at least two hours post inoculation. The rate of cell death on the shell surface increased steadily for the first 40 minutes of drying and tapered through the two hour end point. The death rate increase may have correlated with drying time on the shell surface. Further, the bacteria were able to attach to the shell within 10 minutes of incubation. Morphological examination of cells surviving on egg shells showed collapsing of the surface when dried for 30 minutes. When allowed to dry on the egg shell surface for two hours, Salmonella was able to survive sanitization with either 200 ppm hypochlorite or quaternary ammonium based sanitizer. Interestingly, a more vigorous recovery method was required to remove bacterial cells surviving on the shell surface post sanitization indicating that the sanitizers caused increased attachment. M.S. in Biology, May 2011 Show less
