Salmonella Uses Human Intestines to Foster Growth

The bacteria Salmonella enterica, which is a common cause of food poisoning, takes advantage of the body's immune response to enhance its production of energy. Bacteria have to produce energy in order to survive, either by respiration or fermentation. However, oxygen is sparse in human intestines, so bacteria use fermentation in order to survive. Respiration is much more energy efficient than fermentation is, producing a higher number of ATP.

When Salmonella is injested, it invades the intestine's surface, causing the immune system to produce oxygen radicals that kill of the bacteria. Some bacteria are killed by this process, but many others benefit from a sulfur compound that the oxygen radicals create. This sulfur compound is called tetrathionate, which Salmonella can use instead of oxygen to carry out respiration. As we learned in class, oxygen is needed to act as the final electron recpetor in the elctron transport chain. Tetrathionate acts as the final electron acceptor for Salmonella, which is what allows it to produce energy through respiration rather than the less energetically productive process of fermentation. Tetrathionate had previously been by researchers to promote Salmonella growth in samples, but it was throught that this sulfur compound was not found in living human beings. Stimulating the immune response gives Salmonella an advantage, as it allows them to carry out respiration and thus produce more energy than the other bacteria in the intestine. When this response is stimulated, it also allows Salmonella to spread to other hosts, as the body induces diarrhea and vomiting in an attempt to rid itself of this bacteria.

The symptoms of Salmonella infection include vomiting, fever, abdominal cramps, and diarrhea. While most people recover quickly, it can be fatal in people with suppressed immune systems. Antibiotic treatment is ineffective, as it also ihibits the growth of beneficial bacteria in the body. Researchers are hopeful that targeting sulfur compounds will help stop the bacteria from establishing itself in the intestine.

You can click here for the article that I got my information from or you can click here for a shorter article that basically talks about the same thing.