Streptococcus Group A
Introduction
Group A Streptococcus (GAS), also known as Streptococcus pyogenes, is a bacterium that is generally found in the inner throat and on various parts of the skin. The letter "A" corresponds to a classification of bacteria in the genus Streptococcus according to the structure of the organism's cell wall. This Gram Positive bacterium can cause infections that range from mild to life threatening. It tends to cause relatively mild illnesses, such as streptococcal sore throat (strep throat) and streptococcal skin infections (impetigo). Group A strep can also cause more severe illnesses such as scarlet fever, rheumatic fever, postpartum fever, wound infections, and pneumonia. Signs and symptoms depend on the type of illness caused by the bacterium. These symptoms can usually be seen from one to three days upon infection. Most infections can be treated with antibiotics. This bacterium can be spread by direct person-to-person contact that can be found worldwide. Scarlet fever (known as scarlatina in older literature references) is one serious infection resulting from Group A Streptococcus and is considered an exotoxin-mediated disease. In essence, Scarlet Fever is a more severe case of Strep Throat with the additional symptom of a rash. The toxins (poison) released from Group A Streptococcus can cause the scarlet-colored rash from which this illness gets its name.
Description of Scarlet Fever
Description of the microbe
Include a link if there is an existing microbewiki page. Ex. Salmonella typhi
Group A Streptococcus, a Gram-positive bacteria, is nonmotile and does not form spores. (1) It's cells typically range from 0.6 to 1.0 micrometers in diameter, which is a fairly small size for a bacteria. These cells are usually found in groups and are seldom seen alone. Rather than using aerobic or anaerobic respiration, Group A Streptococcus uses a metabolic pathway of lesser efficiency, fermentation. This makes the cells grow much slower with a lower chance of survival than those bacteria that use aerobic or anaerobic respiration since fermentation is a pathway which does not use the highly effective Electron Transport Chain (ETC). Nutrient-enriched blood is usually required for Group A Streptococcus to grow and they "typically have a capsule composed of hyaluronic acid and exhibit beta (clear) hemolysis on blood agar." (1)
Proven to be an efficient method of classifying this bacteria is the hemolytic reaction that occurs on the blood agar. There is an alpha-hemolysis, a beta-hemolysis and a gamma-hemolysis. Alpha-hemolysis is a partial ("green") hemolysis associated with the reduction of red cell hemoglobin, while beta-hemolysis is associated with the complete lysing of those red cells that surround the colony and gamma-hemolysis is the term used for non-hemolytic colonies. (1) Knowing this information, one can classify Streptococcus Group A bacteria since it is almost always beta-hemolytic. Although this method is not perfectly accurate, it is still very widely used.
Transmission of disease
"Scarlet fever transmission typically occurs through direct contact with throat mucus, nasal discharge, and saliva of an infected person." (1) The microbe can quickly be spread by droplets being released from a sneeze, cough, or by nasal and oral fluids. It can also be transferred by direct skin to skin contact. (3) The microbe displays great tenacity for life since it seems to cling to any object it encounters. (2) The microbe is very driven since it can live outside of an individual for some time making it very difficult to avoid without the right precautions. It can cling to dishes, cups, toys, and any other accessible surfaces. "If you touch your mouth, nose, or eyes after touching something that has these fluids on them, you may become ill." (4) "Numerous epidemics spread by milk have been reported." (2) One of the biggest problems with the transmission of the microbe is that some individuals are the so called walking or unrecognized case which show minimal evidence such as merely a sore throat. (2) These individuals are carriers for the disease without knowing it and without many of the symptoms of an infected individual making the spread of the microbe very easy among the rest of the healthy unsuspecting population. Avoiding contact with an infected person and with the areas they could have contaminated is the best way to avoid contact with the Streptococcus Group A bacterium.
How is it transmitted? Is there a vector (animal/insect)?
Prevention
Why is this disease a problem in [name of country]
Do lifestyle/environment/economics/political issues play a role?
What is being done to address this problem
Include anything being done by the local government or groups as well as efforts by non-local groups.
What else could be done to address this problem
Are there solutions that could be successful but haven't been implemented due to political or economic reasons? Are there successful efforts in other countries? Are there reasons why these efforts may or may not be successful in the country you've focused on? etc. etc.
To analyze the the symptoms and diagnose the disease of an individual, the doctor uses a cotton swab to rub the back of the throat and uses the swab for rapid antigen test or throat culture to check for Streptococcus Group A infection. (1) If test shows positive results for Group A Streptococcus, the doctor will initially prescribe an antibiotic as the main treatment for Scarlet fever. The most common antibiotics used include penicillin, cephalexin, and amoxicillin. These antibiotics should be taken as recommended by the doctor and consumption should not cease until indicated by the prescription.
The main symptoms of Scarlet fever are body aches, fever, and moderate to severe sore throat. The doctor will recommend over-the-counter drugs such as acetominophen (which is commonly referred to as Tylenol and Datril) or Ibuprofen (which is marketed as Advil, Motrin, and Nuprin). Patients under the age of 20 should not take aspirin unless indicated by the doctor. (2) Sponge baths are also used along with the drugs to help combat high fevers. If skin is itching and burning, best remedies available are vaseline and oil or prescription of cream or lotion. (3) To treat a sore throat doctors recommend cold drinks, frozen desserts, or warm liquids such as soups. "Gargling with saltwater (about half a teaspoon salt to 8 ounces of warm water) and sucking on throat lozenges" (2) can be used to treat this symptom. Parents are also advised to purchase a cool mist humidifier to prevent the air and the throat from becoming too dry and causing more severe soreness. It is also highly recommended that a patient obtains plenty of rest and abstain from strenuous activities.
Current research on Group A Streptococcus focuses on the production of its unique proteins. There are over 120 different strains that cause a specific group of diseases. "With the support of the National Institute of Allergy and Infectious Disease (NIAID), scientists have determined the genetic sequence, or DNA code, for five different strains of the Group A Streptococcus organism." (4) Through studying a certain organism's genes, scientists were able to understand the function of specific proteins which are responsible for virulence of the disease. This information is very valuable and is the basis of the development of the Group A Streptococcus vaccines. These vaccines target specific proteins at different stages of the diseases' development. Doctors and researchers claim that effective vaccines will not only prevent specific symptoms but will also help fight the most serious post-infectious complication. (4) Currently research includes studies of determining the spread of the disease across different countries in an effort to characterize the disease.
References
Edited by [insert your names here!], students of Rachel Larsen
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