Toxic Shock Syndrome
Toxic Shock Syndrome
Toxic shock syndrome (TSS) is a serious, life-threatening disease caused by bacteria called Staphylococcus aureus and less typically, Streptococcus pyrogenes. Common causes of skin and mucous membrane infections, some strains of Staph. aureus and Strep. pyrogenes secrete toxins that initiate a cascade of immune reactions. These immune reactions lead to overproduction of immune proteins, and the abnormally high production of these proteins leads to TSS. As its name implies, the most prominent symptom of TSS is shock. During shock, the bloodpressure drops to dangerously low levels. If TSS is not quickly diagnosed and treated with antibiotics, it can be fatal.
A toxin is a chemical that acts as a poison within the body. TSS is caused by toxins released from certain strains of Staph. aureus and Strep. pyrogenes. Not all strains of these bacteria release these toxins. About 30% of Staph. aureus strains and less than 10% of Strep. pyrogenes strains are TSS-toxin-producing.
Toxins that cause TSS are called superantigens because of their effects on the immune system. An antigen is the protein on a bacterial cell or viral coat that certain immune cells, called helper T cells, identify as foreign. Helper T cells recognize antigens by binding to them. When this recognition occurs, the immune system swings into action against the invader and makes specific proteins, called antibodies, which tag the invader for destruction by other immune cells. The TSS toxins are superantigens because the immune reaction they incite is nonspecific and aggressive. Helper T cells binds to the toxins, but instead of activating one small part of the immune system—the antibody production mechanism—the helper T cells-toxin binding “turns on” all of the immune system.
This nonspecific activation of the immune system has devastating effects on the body. As a result of TSStoxins binding to helper T cells, several immune proteins are overproduced. Monokines and lymphokines, proteins that promote the further proliferation of helper T cells, are produced in large quantities. Histamine, a protein that functions in allergic reactions and the inflammatory response, is released from immune cells. These proteins, in turn, exert several physiological effects. Histamine causes blood vessels to dilate, increasing blood circulation. Monokines and lymphokines contribute to the body’s fever response, in which the internal temperature of the body increases in response to an immune signal. The combination of all these effects leads to TSS.
A syndrome is a group of different symptoms and conditions that are traced to one specific cause. acquired immune deficiency syndrome (AIDS), for example, is a cluster of different diseases that stem from infection of helper T cells with human immuno-deficiency virus (HIV). Similarly, TSS is a spectrum of symptoms caused by infection with toxin-producing strains of Staph. aureus and Strep. pyrogenes.
The early stage of TSS is characterized by flu-like symptoms such as sudden fever, fatigue, diarrhea, and dizziness. In a matter of a few hours or days, the blood pressure drops dangerously and a sunburn-like rash forms on the body. The drastic drop in blood pressure is potentially fatal. Circulatory problems develop as a result of low blood pressure, and some extremities— such as the fingers and toes—are deprived of blood as the body tries to shunt blood to vital organs. If the syndrome is severe enough, fingers and toes may become gangrenous due to lack of circulation. TSS can be treated with antibiotics, but these drugs kill only the bacteria that release the toxins: they do not neutralize the toxin that is already in the bloodstream. For treatment to be effective, antibiotics must be given early in the illness, before a large amount of toxin has built up in the bloodstream.
In 1980, several women in the United States were diagnosed with TSS; a few of these women died. When researchers investigated these cases, they found that all the women had been menstruating and using high-absorbency tampons. Since that time, toxic shock has been associated with the use of tampons in menstruating women, who comprise about 50% of the cases of TSS per year. Researchers speculate that tampons provide a suitable environment for bacteria such as S. aureus to grow. After some types of synthetic fiber added to tampons in order to increase absorbency were found to amplify toxins produced in TSS, manufacturers removed the. Today’s tampons are mostly composed of cotton and rayon, and carry a mandated warning about TSS on the outside packaging.
To reduce the risk of TSS, experts recommend that women who use tampons change them frequently (about every two to four hours) and use the lowest-absorbency tampon that is practical. To avoid all tampon-associated risk of TSS, avoid using tampons altogether. Since instituting these guidelines, the incidence of toxic shock has fallen significantly over the past ten years. Currently, the incidence of toxic shock syndrome in menstruating women is between one and 17 cases per 100,000. However, some cases of TSS in women have been associated with the use of contraceptive sponges and diaphragms. Like tampons, these devices should be worn for the shortest time recommended on the package directions, and for no longer than eight hours.
Cases of TSS are also found in people with preexisting skin infections, such as boils and wound infections. Prompt treatment of these conditions can usually prevent TSS. Researchers are also investigating the possibility of genetic predisposition to the disease. In 2002, scientists found a particular combination of
Antigen —A molecule, usually a protein, that the body identifies as foreign and toward which it directs an immune response.
Helper T cell —The “lynch pin” of specific immune responses; helper T cells bind to APCs (antigen-presenting cells), activating both the antibody and cell-mediated immune responses.
Syndrome —A set of diseases or symptoms that are traced to one specific cause; examples include acquired immune deficiency syndrome (AIDS) and toxic shock syndrome (TSS).
Toxin —A poisonous substance.
HLA genes in some people that results in greater susceptibility to serious streptococcal infections, while another combination of HLA genes in others offers protection against the severe consequences of infection.
Nair, M., Alabi, C., Hirsch, P.I. “Toxic Shock Syndrome: A Silent Killer.” Journal of Obstetrical Gynaecology. 8 (November 26, 2006): 825.
Centers for Disease Control and Prevention. “Toxic Shock.” <http://www.cdc.gov/ncidod/dbmd/diseaseinfo/toxicshock_t.htm> <http://www.cdc.gov/ncidod/dbmd/diseaseinfo/toxicshock_t.htm> (accessed on November 27, 2006). Toxic Shock Syndrome Information Service. <http://www.toxicshock.com/> <http://www.toxicshock.com/> (accessed on November 27, 2006).