Staphylococcal Purpura Fulminans

Staphylococcus aureus is a bacterium that is about 1 micrometer in diameter (25,000 of them laid end-to-end will equal one inch). This bacterium is the cause of boils, some types of pimples, infections of in-grown toenails, sinus infections, and more severe diseases such as toxic shock syndrome. Nearly 50% of all humans have this bacterium in their noses, living as a normal part of them.

How does Staphylococcus aureus cause purpura fulminans?

There are many varieties of Staphylococcus aureus—we call them strains. Some strains make toxins (poisons) that they secrete into their surroundings. These toxins have the ability to cause very high fever, significant drop in blood pressure and other bad effects on humans. One of these toxins identified in the Schlievert laboratory in 1980 is toxic shock syndrome toxin. This toxin is made by about 5% of all Staphylococcus aureus. This toxin causes all of the tampon (menstruation-associated) cases of toxic shock syndrome. Toxic shock syndrome is characterized by high fever (>102OF) and significant drop in blood pressure (this means the person may faint or have dizziness upon standing). There are two other toxins that are related to toxic shock syndrome toxin that can cause toxic shock syndrome. They are called enterotoxin B and enterotoxin C. All three toxins have the same effects on humans—to cause fever and drop in blood pressure.

Purpura fulminans means that the disease has a bloody rash associated with it (purpura) and is very rapidly progressing (fulminans—from fulminant). The rest of the illness is toxic shock syndrome (fever and drop in blood pressure). At this time, we do not know the mechanism behind why the bloody rash occurs, except it occurs because for some reason the blood stream is clotting up. When that happens, the blood vessels and organs begin to die. When the blood vessels die, blood leaks into the surrounding area and gives the bloody rash.

The disease Staphylococcal Purpura Fulminans begins after the person has some kind of respiratory virus infection (cold, flu, croup, laryngitis). The virus damages the respiratory tract (airway) and allows Staphylococcus aureus to cause infections of the damaged areas. Remember that many people have Staphylococcus aureus in the nose, and many of these make toxins. The Staphylococcus aureus bacteria that make one or more of those three toxins (toxic shock syndrome toxin, enterotoxin B, enterotoxin C) will then make their way into the lungs and cause pneumonia. The function of the lungs is to transfer oxygen into the bloodstream very quickly. This transfer function also allows the toxins to be transferred into the bloodstream. The toxins then cause fever and drop in blood pressure. For some unknown reason the toxins are also activating clotting within the blood vessels. This is also now happening very rapidly because Staphylococcus aureus can make large amounts of toxins.

How is the disease treated?

Staphylococcus aureus strains can be resistant to many antibiotics. Thus, patients will likely be treated with more than one antibiotic, including an antibiotic referred to as vancomycin. These will kill the Staphylococcus aureus. However, they do not kill the toxins that have been produced since the toxins are not alive. The patients will be treated with fluids intravenously to keep their blood pressure up to near normal. Many patients will also be treated with intravenous antibodies in attempt to bind to and neutralize the toxins (so they cannot cause tissue damage). Finally, the patients will be given a drug that slows clotting to prevent the clotting that closes up the bloodstream. This drug consists of activated protein C, whose normal job in humans is to slow clotting.

Can this disease be spread?

Staphylococcus aureus is one of the most common bacteria that live in humans. It can also live outside of humans for days on doorknobs, bus door handles, pencils, or any other object that humans might touch. The bacterium is spread from one human to another human by many routes, including coughing, touching, touching objects that have been contaminated by humans etc. Many people already have the bacterium in them, and it is the viral infection that begins the process. There is very little that can be done to prevent the disease. What can be done is to know that if high fever and dizziness upon standing (or loss of consciousness) occur following respiratory viral infection, medical help should be sought.