TITLE: Streptococcus Pyogenes, Flesh Eating Bacteria
AUTHOR: Sara Chou
DATE: May 19, 2011


ABSTRACT: The purpose of this research project is to give people information on the bacteria called Streptococcus pyogenes. The question that will be explored in this project is how does S. pyogenes cause the destruction and deterioration of flesh and whether or not there is a cure for the disease? S. pyogenes is a Gram positive bacteria and its morphology usually appears as a chain of cocci. S. pyogenes is anaerobic, not mobile and does not produce endospores. S. pyogenes is a group A streptococcus bacteria (GAS) because it is associated with the more serious streptococcal infections. S. pyogenes is a bacterial infection that in more serious cases can cause the destruction skin and muscle tissues. However, this bacteria can produce minor symptoms that could progress to serious levels if the infection is not treated right. The most common and most known S. pyogenes infection is streptococcal pharyngitis, better known as strep throat. Though strep throat is a minor illness, if it is not treated correctly, it can lead to rheumatic fever and damage to organs. The two most severe streptococcal infections are necrotizing fascititis, the flesh eating bacterial infection and toxic shock syndrome. This research project will look at the difference between the varying degrees of streptococcal infections. This project will discuss the effects of a S. pyogenes infection, both minor and severe. The project will also go over how to prevent infection. I will talk about a research project in which scientists tried to discover the effects of a streptococcal infection on subjects with varying ages and medical cases.
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Streptococcus pyogenes (correlatingcancer.com)


INTRODUCTION: In microbiology our class has been learning about many different bacteria. We have learned the names of many types and some of their primary features. I was interested in S. pyogenes because as a child I constantly had streptococcal pharyngitis and I wanted to further my knowledge on the topic. I also wanted to see why so many people fear this strain of bacteria since it is often called the “flesh eating bacteria.” I wanted to discover whether or not this bacteria actually causes death and what the rate of survival was if one was infected.

DISCUSSION: Streptococcal infections occur when bacteria contaminate cuts or open sores and penetrate the body's defenses (Haggerty). S. pyogenes is considered a group A streptococcal bacteria (GAS) and is commonly found in the mouth or skin. Group A streptococcus bacteria are distinct and are b
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Blood Agar plate with Streptococcus pyogenes (amrita.ac.in)
eta-hemolytic which means that the bacteria creates a toxin that causes the lysis of red blood cells and forms a clear zone of hemolysis on blood agar (Falk). GAS is transmitted by direct contact with saliva, nasal discharge or open wounds of an infected person (Haggerty). Streptococcal infections invade the body and basically overwhelm one's immune system. The bacteria can attack healthy tissue and in more serious cases, the bacteria targets tissues weakened from illness and injury. Group A streptococcal infections are very common, but it is not known why certain strains are more serious while others are not (Haggerty). Mild infections pertain to the invasion of healthy tissue while severe cases pertain to the invasion of weakened tissues. Infection can lead to mild symptoms or severe symptoms such as organ system fail. The mild cases of S. pyogenes include strep throat and skin infections while serious infections include necrotizing fasciitis and streptococcal toxic shock syndrome (Haggerty). Strep throat or as its scientifically named, Streptococcal pharyngitis, is the most common type of strep infection. This type of primary infection is usually not fatal and is most frequently seen in school aged children (Haggerty). Children are more susceptible to Streptococcal pharyngitis at a rate of infection of 15% to 40% greater than adults (National).


Streptococcal toxic shock syndrome
Streptococcal toxic shock syndrome is a rapidly progressive effect that damages and can sometimes shut down internal organs (Haggerty). Streptococcal toxic shock syndrome is a component of necrotizing fasciitis in which many times patients suddenly develop and can die. This syndrome usually causes a dramatic drop in one's blood pressure and can lead to tachycardia as well as kidney and respiratory failure within a matter of hours. It has been stated that 60% of patients that express streptococcal toxic shock syndrome die (Shaffer). If streptococcal toxic shock syndrome has taken place, systems begin to fail and tissues are not supplied with blood and cannot survive, leading to necrotizing fasciitis.

Necrotizing fasciitis
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Diagram of Necrotizing fasciitis (primehealthchannel.com)

Necrotizing fasciitis occurs when S. pyogenes attacks muscle tissue, skin and fat. This infection takes place in the fascia layer of connective tissues and blood vessels (Hegemony). The bacteria invades the body through a cut, scrape or open sore and while the bacteria grows, it releases toxins. Infection site appears to be a red, painful spot and changes to a purple color. It has been hypothesized that the pain from the infection comes from the fact that bacterial protease are digesting tissue. From there, the site becomes black and pieces of tissue begin to die. Tissues become gangrenous and decomposition of
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Necrotizing fasciitis (bioweb.com)
tissues becomes more rapid. At this point, the skin usually breaks open and oozes fluids (National). There are many symptoms of an infection of this magnitude, these including streptococcal toxic shock syndrome, fevers, nausea, sore throat, headaches, dehydration and rashes. Necrotizing fasciitis is a rare infection but nonetheless a deadly one. It has been stated that only 500 cases of necrotizing fasciitis have been reported since 1883, however the death rate is around 75% (Haggerty). Both streptococcal toxic shock syndrome and necrotizing fasciitis have high death rates, killing about 15% to 20% of its victims (Shaffer).




Case studies of Streptococcus pyogenes
One study showed that people who are older are more susceptible to a streptococcal infection. This study was done on mice in order to better understand immune dysfunction and potentially find a strategy to enhance immunity. One of the purposes of the test was to see the effects of S. pyogenes on the immune system of the elderly. Both young and old mice were inoculated with S. pyogenes at the start of the experiment. Scientists discovered that in older mice their immune response changed more dramatically then those of younger mice. Older mice experienced changes in T-cells and a decreased ability to produce antibody isotopes. A decreased number of T-cells implies that one's immune responses are having a difficult time fighting off an infections. This means that the patient is more susceptible to pathogens and that the disease is over powering the patients immune system. This discovery supports the fact that streptococcal infections are usually worse in people ages 50 years or older. The study also showed that the older mice first line of defense was impaired by their age while younger mice first line of defense could withstand infection longer. It was also shown that the organs, such as the liver of the older mice were not in as good condition as the younger mice. Older mice showed higher levels of systemic inflammation as well. This study has proved that age is key when it comes to human infections. Older mice were treated with M-CSF which showed some re-population of tissue macrophages and an increase in immunity during infection. Scientists agreed that M-CSF could be useful in the development of new approaches to enhance immunity (Goldmann). The study supported the idea that mild streptococcal infections are most likely to infect the young while more serious streptococcal infections effect the elderly.

Preventions and Treatments
In order to prevent from getting a Streptococcal infection, one can minimize the transmission of S. pyogenes by washing their hands wells and frequently. Tissues and eating utensils must be properly disposed and the infected person is encouraged to avoid close contact with uninfected people (Haggerty). The most useful and common treatment for S. pyogenes infections is Penicillin. It has been stated that there are no reports of group A streptococcus bacteria strains having resistance against Penicillin. Penicillin is taken for 10 days for infects like Streptococcal pharyngitis (Shaffer). However, if a patient is allergic to Penicillin and has a S. pyogenes infection, leg.jpgother medications can be administered. About 10% of the time, Penicillin is not effective and then any of the following may be given to the patient; these including Erythromycin, Loracarbf, Cefuroxime, Azithromycin (Haggerty). If a patient exhibits necrotizing fasciitis, then treatment includes antibiotics and sometimes surgery to drain the infected area. Surgery is also used to remove dead tissues and amputation is also a possible treatment (National). If a rash on the skin doubles in size in one or two days and is accompanied by tenderness, swelling or fever, that person should see a doctor as soon as possible. Another sign of a streptococcal infection is shaking or chills that are caused by a break in the skin. If a streptococcal infection is suspec
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Streptococcal pharyngitis- strep throat (drtummy.org)
ted or exhibited in a person, it is advised to seek medical attention as soon as possible.


Conclusion
The key to streptococcal infections in humans is age. Younger people and children are more susceptible to mild streptococcal infections while older people are more susceptible to more serious streptococcal infections. The level of streptococcal infection also depends on the immune system of its victims as well. Group A streptococcal bacteria is considered to be contagious and can cause streptococcal pharyngitis and in serious case can cause necrotizing fasciitis. It should be known that the strain causing the “flesh eating bacteria” is rare and if noticed early, can be treated with antibiotics.

LITERATURE CITED:
  1. Falk, Peter. “Flesh Eating Bacteria: Streptococcus Pyogenes.” bioweb.com. n.d. 16 April 2011.
  2. Goldman, O., Lehne, S., Medina, E. “Age-Related Susceptibility to Streptococcus pyogenes Infection in Mice: Underlying Immune Dysfunction and Strategy to Enhance Immunity.” Journal of Pathology. 220.5 (17 November 2009). Web. 10 April 2011.
  3. Haggerty, Maureen, Davidson, Tish. “Streptococcal Infections.” The Gale Encyclopedia of Medicine. Vol 5. (2008). Web. 16 April 2011.
  4. Shaffer, Marjorie. “Strep Strikes Back.” American Druggist. 210.5 (1994). Web. 16 April 2011.
  5. How 'Flesh Eating' Bacteria Really Works.” hegemony.wordpress.com. Hegemony in Health and Science. n.d. 16 April 2011.
  6. “Strep throat.” ncbi.nlm.nih.gov/PubMed Health. National Center for Biotechnology Information. n.d. 10 January 2011.