CLASS CODE: MP202
Total Word Count 1492
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Toxic shock syndrome (TSS) is an uncommon but serious systemic infection which can occur in males and females of all ages. Symptoms include fever, hypotension and desquamation of the skin. The two main micro-organisms that cause TSS are Staphylococcus aureus and Streptococcus pyogenes. TSS is associated with the use of highly absorbent tampons but can also arise from Staphylococcus aureus infection at non-genital areas (for example wounds). "From a UK population of around 60 million there were about 40 cases reported each year, half of which are associated with women using tampons." 
Staphylococcus aureus are anaerobic, gram positive bacterium. They lie harmlessly in the mucous membrane of the vagina. Though, the bacteria can grow rapidly if the tampon is left in the vagina for an overextended period of time. This is being due to the warm conditions and viscous fluid present at the time. Bacterial invasion depends on the way the tampon has been inserted into the vagina. Super absorbent tampons can make the vagina dry resulting in the wall being prone to microscopic tearing and small blood vessels bursting.  It is estimated that over 90% of S. aureus strains are the cause of menstrual-related TSS.  Bearing in mind that this is only one of the circumstances how the infection can emanate. Another type of TSS is Streptococcus TSS (STSS) which is caused by the bacteria Streptococcus pyogenes. STSS is rarely a result of tampon use and is more likely to develop in a surgical wound, skin infection or even in a cut. The symptoms are similar to that of TSS. 
S. aureus targets endothelial cells because they produce fibrinolysin enzymes (such as Staphylokinase) which help the bacteria invade the bloodstream.  S. aureus starts colonizing the vaginal wall's mucous and releases their exotoxin Toxic shock syndrome toxin-1 (TSST-1).  TSST-1 is produced by excessive production of cytokines through T cells. TSST-1 helps bind class II MHC receptors and T-cell receptors. As a result T-cell responses are stimulated without the presence of specific antigens.  TSST-1 possesses features of a superantigen where it can stimulate a response from 5% to 30% of the T-cell population, whereas specific antigens can only stimulate a response from 0.01% to 0.1% of the T-cell population.  The overall effect of excessive cytokine is circulatory collapse which is followed by a hypovolemic shock resulting in multiorgan failure. In a serologic study, it has been proven that over 90% of adults have antibodies against TSST-1. On the other hand half the patients who suffer TSS do not develop protective antibodies after recovery. 
Samples were analysed in a microbiology lab in order to identify the unknown micro-organism causing the disease and hence to verify the doctor’s diagnosis. The first step taken was observing the micro-organism reaction to Gram's stain under a light microscope. The result was gram positive as the colonies were blue/violet. When observing the micro-organism's cellular morphology, the colonies resembled clusters of grapes meaning it was of staphylococcus nature.
The results from the first observation were confirmed by viewing the characteristics of the micro-organism's colonies on selective and differential media macroscopically. The first medium contained blood agar, Neomycin and a 0.4μg disc of Bacitracin. Bacitracin is an antibacterial agent which mainly acts on the cell wall of gram positive micro-organisms. It was added to see the difference in degree of resistance of groups A and B of Streptococci micro-organisms were to...
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