Salmonella Bacterium and Antibiotics

Subject: Other Medical Specialties
Pages: 3
Words: 744
Reading time:
3 min

Salmonella is a bacterium commonly associated with a foodborne illness caused by the salmonellosis infection. The disease is responsible for 1.2 million infections and 450 deaths in the United States annually. There are more than 2,500 various serotypes identified. This paper will discuss a relatively common Salmonella enterica. It is gram-negative with rod-shaped bacteria. Salmonella is anaerobic as it does not require oxygen for growth; however it has the ability to survive within an oxygenated environment, making it a facultative bacterium. Salmonella enterica does no ferment or lactose, which places it in the Pseudomonas genus. The bacterium can survive in a wide range of conditions, including temperatures ranging from 5.2-46.2°C and a PH of 3.8-9.5, which are relatively broad margins. Growth can be inhibited in food through a variety of preservatives such as benzoic, sorbic, or propionic acids. Salmonella enterica is has a spindle (rod) shape. Its colonies are typically large with translucent and slightly irregular margins as well as slightly umbonate elevation.

Salmonella enterica does not reside in the human microbiome and is considered a pathogen. The bacterium is carried by wild and domestic birds or animals as well as any foods (such as vegetables) that have been exposed. Transmission is common through physical contact with the fecal or oral matter of infected foods, animals, or humans. Once inside the human body, usually through ingestion of food, Salmonella enterica has to endure low stomach PH and host defense mechanisms before infection begins. The bacterium has both structural and physiological characters which support its virulent nature and leads to acute infection. For example, the O side chains of lipopolysaccharide molecules may vary in length and structure, which helps Salmonella resist an organism’s immune response. The bacterium also has fimbriae which allows it to attach to host cells and gene expressions necessary for invasion. These virulence factors are encoded into Salmonella pathogenicity islands. Once the infection occurs, Salmonella releases a heat-labile enterotoxin which leads to the decrease of intestinal fluids. Furthermore, a heat-labile cytotoxin is discharged, which causes inflammation due to deterioration of the intestinal mucosal surface. Typically, infection of a non-typhoidal Salmonella strand is confined to the intestine.

Antibiotics are used to treat Salmonella in more complicated cases, when the bacterium has spread outside the intestine and into the bloodstream or if a patient is immunosuppressed. One of the most common antibiotics used is Ceftriaxone. It is a broad-spectrum cephalosporin beta-lactam antibiotic. It is used against susceptible bacterial infections. It has in vitro mechanisms against both gram-positive and negative, aerobic and anaerobic bacteria. It works by disrupting mucopeptide synthesis in the cell wall of the targeted bacteria. The beta-lactam moiety can bind with carboxypeptidase and other enzymes in the membrane, which is responsible for cell division and cell wall synthesis. The binding impedes the formation of cell walls, thus disputing the process of division and cell function, which eventually results in its death. Antibiotics are able to kill bacteria cells without harming the human host by specific targeting of bacteria-specific characteristics or metabolic pathways. For example, cell walls with the macromolecule peptidoglycan, which is common in bacteria but is not produced in human cells. Metabolism is targeted through mechanisms such as inhibiting the enzyme dihydropteroate synthase, which is responsible for the production of folic acid. While folic acid can diffuse into human cells through the membrane, bacteria with cell walls are forced to produce their own. Sulfonamide compounds in drugs disrupt the protein synthesis, and the cell cannot grow.

Salmonella is a common foodborne bacterium that is highly infectious and adaptable to survival and treatment. It is a pathogen that has a high virulence factor due to its ability to resist immune defense and invade healthy cells. As a result, severe loss of fluids and infection occurs in the intestine. Although antibiotics are not recommended to treat Salmonella, they can be effective at disrupting metabolic protein synthesis, which is responsible for cell growth and cell wall formation. Future drug development is focused on slowing the growth of Salmonella by essentially “starving” it and disrupting metabolic processes. The bacterium’s considerable weakness is its dependence on a nutrient without which its life becomes unsustainable. Fructose-asparagine has been found to be the critical food source for Salmonella, and decreased access to it shows considerably less inflammation in the intestine. New drugs are attempting to target nutrient transports as the potentially revolutionary treatment of Salmonella.