Bacillus anthracis
by Robert Spicuzza
Background 
Bacillus anthracis is a gram-positive spore-forming rod. It was the first bacterium to be used to prove that bacteria caused diseases, when Robert Koch (1877) produced anthrax spores and injected them into animals. Bacillus anthracis is a commonly found in soil of grazing areas. Bacillus anthracis is not a major threat to humans and natural cases are rare even where spores are present.
(images provided by the Microbe library)
Encounter
Bacillus anthracis is commonly found in soil in low amounts. It effects livestock and can be transmitted to humans through improper handing of an infected animal or by eating undercooked meat from the animal. It is rare for human-to-human infection.
Types of Infections and Symptoms
There are 3 main ways that anthrax can infect you. Cutaneous infections are the most common and the least deadly. The normal infection produces a small painless ulcer. If left untreated the Bacillus anthracis may make its way into the bloodstream and death will occur in about 20% of cases. Intestinal infection which comes from eating undercooked meat, and is more deadly then a cutaneous infection but less deadly then a inhalation infection. The symptoms are severe stomach pains along with diarrhea. The death rate if left untreated is between 25% and 60%. Inhalation infection is the most deadly of the infections and happens when you inhale Bacillus anthracis spores. The disease initialy resembles the common cold. This is not the uncommon type of infection, however it is important because of the possible bio-terrorism that could be associated with it. It is fatal if left untreated.
How it avoids the immune system and damages the host
Bacillus anthracis is a unique because it’s the only one that has a capsule of poly-D-glutamate polypeptide. The capsule helps the bacteria avoid being phagocitzed. This lets the bacteria gain a foothold inside the host.
Bacillus anthracis toxin is an A-B toxin comprised of 3 protiens. The protective antigen the edema factor, and lethal factor. Individually all 3 proteins are harmless, but when together they are able to attack the lungs. The first protein is the protective antigen which helps neutralize antitoxin antibodies. The edema factor protein helps bolster the Virulence and is responable for seeking out the target cells. The last protein is the lethal factor, which is protein that is causes cell death. The toxin seeks out our cells, and is able to injects the toxin directly into them, the toxin is deadly inside the cell and quickly produces cell death. Once the bacteria make enough toxins, it is deadly since antibiotics cannot destroy the toxin since it has the protective antigen. (image provided by the Microbe library)
Why is this bacteria so important
Bacillus anthracis has been around since the domestication of animals, so why is it so talked about? Bacillus anthracis produces a spore that is extremely resilient. So by releasing the spores (lets say by using a missile in the atmosphere) the spores would be able to be inhaled and in almost all cases, are fatal if left untreated. When the terrorist began mailing anthrax they hoped that the spores would spread all over the mail equipment, and if they had happened would have been disastrous.
Vaccine
The vaccine was made from an attenuated strain of B. anthracis. The vaccine contains no cells in the culture and is made up of the coat of anthrax. This makes the side effects from the vaccine small. There is however an ongoing debate that the vaccine given to soldiers in Desert Strom, some of those that recieved the vaccine did come down with a sickness however there is no evidence to back this claim up. When tested the vaccine provided over 90% effective. With no major side effects.
Treatment
There are 3 main antibiotics, which are used to treat B. anthracis, doxycycline, ciprofloxacin, or amoxicillin. Doxycycline is more recommend because ciprofloxacin is a new family of antibiotics and they do not wish to use it fully because of the fears that bacteria will become resistant to it, and doxycycline is less used in treatment, so bacteria becoming resistant to it have less of an overall effect. However the treatment of anthrax has several side effects, along with having to take the antibiotics for 60 days to make sure that all the spores have germinated. The side effects of the drugs are nausea, mild diarrhea, stomach pain, headache and dizziness, life-threatening allergic reaction, liver damage, high blood pressure and blurred vision is also possible.
Links
http://www.microbelibrary.org/
http://www.bact.wisc.edu/Bact330/lectureanthrax
http://defenselink.mil/other_info/agent.html
http://hopkins-biodefense.org/pages/agents/agentanthrax2002.html