Corynebacterium diphtheria targets cells of the mucosa membranes of the upper respiratory tract and cutaneous tissues of the skin. Rarely, infection can occur at other mucosal sites such as the eyes, ears, or genitals (CDC, 2016). C. diphtheria bacteria produce an exotoxin, diphtheria toxin, and release it to their external environment at the site of infection. From there, the toxin can travel through the bloodstream and affect different cells throughout the body, and block their protein synthesis (Lo, 2017).
Humans are the single recognized reservoir of C. diphtheria bacteria (CDC, 2016). Diphtheria can be transmitted from person to person through direct contact with respiratory and nasopharyngeal secretions, as well as with discharges from skin lesions caused by the …show more content…
diphtheria to cause diphtheria depends on its ability to produce the diphtheria toxin. The bacteria can produce the toxin only if it is infected by a bacteriophage carrying the DNA sequence encoding the toxin, the tox gene. The bacteriophage infects the bacteria and enters the lysogenic stage, integrating the tox gene into the bacterial genome. The bacteria live and continue to reproduce normally, while the prophage is transmitted to subsequent daughter cells with each cell division (Holmes, 2000). However, the expression of this gene is controlled by a bacterial repressor protein, DtxR. The repressor is iron dependent and is inactivated when iron concentrations are low, resulting in the production of the toxin (Hadfield, 2000). The toxin is released from the bacterial cells in the form of two cleaved chains, the A (active) and B (binding) domains, held together by a disulfide bond. As the concentration of the toxin increases, local tissue is destroyed and allows for the toxin to spread throughout the body via the circulatory system. Although the diphtheria toxin does not target specific cells, the myocardium, kidneys, and the nervous system are most affected (Hadfield,
Humans are the single recognized reservoir of C. diphtheria bacteria (CDC, 2016). Diphtheria can be transmitted from person to person through direct contact with respiratory and nasopharyngeal secretions, as well as with discharges from skin lesions caused by the …show more content…
diphtheria to cause diphtheria depends on its ability to produce the diphtheria toxin. The bacteria can produce the toxin only if it is infected by a bacteriophage carrying the DNA sequence encoding the toxin, the tox gene. The bacteriophage infects the bacteria and enters the lysogenic stage, integrating the tox gene into the bacterial genome. The bacteria live and continue to reproduce normally, while the prophage is transmitted to subsequent daughter cells with each cell division (Holmes, 2000). However, the expression of this gene is controlled by a bacterial repressor protein, DtxR. The repressor is iron dependent and is inactivated when iron concentrations are low, resulting in the production of the toxin (Hadfield, 2000). The toxin is released from the bacterial cells in the form of two cleaved chains, the A (active) and B (binding) domains, held together by a disulfide bond. As the concentration of the toxin increases, local tissue is destroyed and allows for the toxin to spread throughout the body via the circulatory system. Although the diphtheria toxin does not target specific cells, the myocardium, kidneys, and the nervous system are most affected (Hadfield,