Overview of Topics Definition Diagnosis Description Treatment Background Complications and Risk Factors Microbial physiology Transmission Group A Streptococci Prevention Biochemistry Prognosis Mode of Infection Living with the Disease Symptoms Research
Definition Flesh-eating disease is more properly called Necrotizing fasciitis, a rare condition in which bacteria destroy tissues underlying the skin. This tissue death, called necrosis or gangrene, spreads rapidly. This disease can be fatal. The disease may also be called synergistic gangrene, among other terms.Definition from medical encyclopedia
DescriptionAlthough the term is technically incorrect,flesh-eating disease is an appropriatedescriptor: the infection appears to devourbody tissue. The arms and legs are mostoften affected, but the infection may appearanywhere. For example, Fourniersgangrene is a flesh-eating disease in whichthe infection encompasses the externalgenitalia.
BackgroundThe disease was first discovered in 1783, inFrance. Doctors noted that it occurredsporadically throughout the 19th and 20thcenturies. The disease was usually restrictedto military hospitals, especially in war times.However, there have been some outbreaks incivilian populations. The disease appeared tomarkedly decrease in frequency after WWII,and reemerged worldwide in the 1980s.
Microbial PhysiologyFlesh-eating disease is divided into two types.Type I is caused by anaerobic species incombination with facultative anaerobicorganisms such as streptococci (non-group A),enterococci, and Gram-negative rods. Type II,is called hemolytic streptococcal gangrene,and is caused by group A streptococci; otherbacteria may or may not be present.
Microbial PhysiologyAlthough Type I is far more common thanType II, It isn’t nearly as dangerous. Mostdeaths and serious infections that areirreversible are caused by Type II infection.
Microbial PhysiologyNecrotizing fasciitis can also be caused bymarine vibros(gram negative bacteria.) Thisis usually an option only when a person hasbeen bit by a fish or shellfish. Necrotizingfasciitis infections can also be caused byfungus. These are rare and usually occur inpatients with weakened immune systems.An example of a fungal infectant isMucormycosis.
Group A Streptococci ( Streptococcus pyogenes) viewed directly by Electron micrograph of transmission electron microscopy (TEM). Chains of Streptococcus pyogens (96,000X) streptococci are clearly evident. To remove cell surface proteins, cells were treated with trypsin prior to preparation and mounting. Strain: D471; M-type 6. (6,500X)Pictures Courtesy of “The Center of Disease Control”
Group A Streptococci Group A streptococcus is a bacterium often found in the throat and on the skin, people may carry Group A streptococci(GAS) in their throat or on their skin and have no symptoms of illness at all. Most GAS infections are relatively mild illnesses such as "strep throat," or impetigo. On rare occasions, these bacteria can cause other severe and even life-threatening diseases.Description of Group A Streptococci is from medical encyclopedia
Group A Streptococci A picture of Streptococcus pyogenes, part of the Group A Streptococci family. A micrograph with computer aided coloring of Streptococcus pyogenes (25,000X)Pictures Courtesy of “The Center of Disease Control”
Group A StreptococciSevere, sometimes even life-threatening, GASdisease occurs when bacteria get into parts ofthe body where they usually are not found,such as the muscle, lungs or the blood.Invasive GAS infections occur when thedefenses of the person fail to keep the bacteriaout of the body.
Group A Streptococci cont…This may occur when a person has sores, cutsor other breaks in the skin that allow thebacteria to get into the tissue, or when theperson’s ability to fight off the infection isdecreased because of chronic illness or anillness that affects the immune system. This isnot the only factor, some virulent strains ofGAS are more likely to cause severe diseasethan others.
The Biochemistry of the DiseaseUsually the bacteria that cause Necrotizingfasciitis releases enzymes and toxins thatspread rapidly through the body. Almostevery type of bacteria produce differentenzymes for example, Streptococci andstaphylococci produce hyaluronidase, whichdestroys hyaluronic acid which is an essentialpart of connective tissue.
The Biochemistry of the Disease Multi-organ failure is also caused by Necrotizing fasciitis by the secretion of a super antigen by a certain strain of streptococci causing clones of T4 lymphocytes which activate cytokines, resulting in the production of oxygen free radicals and nitrous oxides.Pictures courtesy of adam.com
Mode of Infection In nearly every case, a skin injury precedes the disease. As bacteria grow beneath the skins surface, they produce toxins that degrade the tissue. Almost any puncture of the skin has the potential of becoming an infection.Pictures courtesy of adam.com
SymptomsThe following symptoms are associated with the disease.
Symptoms • Swelling of the infected area • Black patches that are filled with pusPictures courtesy of MD Challenger
Symptoms • Discoloration in the area of the infection • It may appear reddened, bronzed, bruised, or purple (purpuric) • It progresses to dusky, dark colorPictures courtesy of adam.com
Symptoms • There is visible dead tissue • The skin breaks and open wounds form • Fever • The combination of the symptoms results in organ failurePictures courtesy of adam.com
Symptoms Normal skin is held tightly by proteins that make up the connective tissue that keep the dermis, epidermis and the muscle tightly connected.Pictures courtesy of adam.com
Symptoms But when bacteria invades the skin through open wounds and punctures of the skin, they cause devastating results by “eating” the protein and the connective tissue.Pictures courtesy of adam.com
Symptoms If left untreated the Bacteria will continue eating and destroying the skin and tissue beneath it until the muscle is infected, when this happens there is no hope of saving the person unless the infected area is surgically removed to keep the bacteria from spreading.Pictures courtesy of adam.com
Symptoms Comparing the uninfected skin to the early and advanced forms of the disease: Normal skin Early stage Advanced stagePictures courtesy of adam.com
DiagnosisThe appearance of the skin, paired with pain andfever raises the possibility of flesh-eating disease.An x ray, magnetic resonance imaging (MRI), orcomputed tomography scans (CT scans) are veryhelpful in diagnosing flesh eating bacteria.Necrosis is evident during exploratory surgery,during which samples are collected for bacterialidentification. CT scan (computed tomography scan): Cross-sectional x- rays of the body are compiled to create a three-dimensional image of the bodys internal structures.
Diagnosis A picture of a slide that was taken from an infected site of a patient, the streptococci cells are clearly seen. The bacteria have been stained with a Gram Streptococcus pyogens viewed under a light microscope (1000X) Stain.Pictures courtesy of the CDC
Diagnosis• The best diagnosis is visual (i.e. symptoms)• X-ray• Magnetic resonance imaging• Computed tomography (CT scans)• Exploratory surgery• Swab streaking of the infected area and viewing microbes under microscope is helpful in bacterial identification.
DiagnosisX-ray, magnetic resonance imaging (MRI)and computed tomography scans revealwhat is underlying the skin and are used toshow the feathery patterns in the tissue thatare caused by the accumulation of gas indying skin.
Diagnosis Computed tomography demonstrates soft tissue gas collection from an invasive Group A Streptococci Bacteria. Gas Gas vesicles vesiclesPictures courtesy of CDC
Treatment Although a neutrophil can kill this bead-like string of Streptococcus pyogenes, this particular strain of bacteria expresses streptolysin-s on its surface which causes the white cell to self-destruct. The white cells lytic granules, which are supposed to fire their antibacterial contents onto the bacteria, are emptied into the white cells cytoplasm instead, leading eventually to cell membrane lysis. Treatment of the disease begins when the first bacterium enter your body through a wound, but when dangerous and rare strains of the disease enter your body, the body’s defenses(macrophages) cannot fight off the infection and antibiotics are needed.Picture and description courtesy of www.cellsalive.com
TreatmentRapid, aggressive medical treatment, specifically,antibiotic therapy and surgical debridement, isimperative. Antibiotics may be applied andinclude penicillin, an aminoglycoside or third-generation cephalosporin. Analgesics areemployed for pain control during surgicaldebridement, in which dead tissue is strippedaway. After surgery, patients are rigorouslymonitored for continued infection, shock, or othercomplications. If available, hyperbaric oxygentherapy can also be used.
Risk factors and Complications Few people who ever come in contact with GAS will develop invasive GAS disease. Most people will have a throat or skin infection, and some may have no symptoms at all. Although healthy people can get invasive GAS disease, people with chronic illnesses like cancer, diabetes, and kidney dialysis, and those who use medications such as steroids are at a higher risk.
TransmissionWhile group A streptococcus is passed fromperson to person in the air or through casualcontact as in strep throat, Necrotizingfasciitis doesn’t transmit as easily. In orderto contract the disease from another person,there has to be a cut or opening in the skinand the opening coming in contact with theopen wound of the infected person.
PreventionThe spread of all types of GAS infectioncan be reduced by good hand washing,especially after coughing and sneezing andbefore preparing foods or eating. Personswith sore throats should be seen by a doctorwho can perform tests to find out whetherthe illness is strep throat.
PreventionAll wounds should be kept clean andwatched for possible signs of infection suchas redness, swelling, drainage, and pain atthe wound site. A person with signs of aninfected wound, especially if fever occurs,should seek medical care.
PreventionIt is not necessary for all persons exposed tosomeone with an invasive Group A Strepinfection (i.e. Necrotizing fasciitis or streptoxic shock syndrome) to receive antibiotictherapy to prevent infection. However, incertain circumstances, antibiotic therapymay be appropriate. That decision should bemade after consulting with your doctor.
PrognosisFlesh-eating disease has a fatality rate of about30%. Diabetes, arteriosclerosis,immunosuppressant, kidney disease, malnutrition,and obesity are connected with a poor prognosis.Older individuals and intravenous drug users mayalso be at higher risk. The infection site also has arole at how serious the infection is. Survivors mayrequire plastic surgery and may have to contendwith permanent physical disability andpsychological adjustment.
Living with the DiseaseMost people who survived the horribleordeal with the flesh eating bacteria havemissing limbs and body parts. Often peoplechoose to cut extra skin from such places astheir thighs to cover the missing patches ofskin cut off to limit the infection site. Somepeople had plastic surgery to repair theirskin in instances where the infectionoccurred on their faces.
Living with the Disease A patient out of the surgery room after a flesh eating bacteria disease infected his leg. An arm infection.Pictures courtesy of e-medicine
ResearchResearchers do not know why the normally mildGroup A Streptococcus bacteria sometimesbecomes a more serious threat. They are unsureexactly why Group A Streptococcus may causeminor infections, such as strep throat, in somepeople, and very serious infections, such as toxicshock syndrome or necrotizing fasciitis, in others.Bacteria have many different characteristics thatcan change over generations, keeping in mind thata generation for bacteria can be as short as 20minutes.
ResearchMany scientists believe the bacteria makesproteins that cause the bodys immune system todestroy both the bacteria and body, in addition toproteins that destroy tissue directly. There is novaccine available to prevent group A streptococcalinfections. Since there are many types of group Astreptococci, one of the biggest problems facingresearchers has been how to make one vaccineagainst all the different types of bacteria.
Thank you for listening to our presentation. For more information about Group A Streptococci and the diseases it causes visit:www.emedicine.com or call the the Center for Disease and Control at 1-800-311-3435.Pictures and statistical information were used from: www.adam.com www.CDC.gov www.nnff.org www.emedicine.com www.emergency.com/strep-a.html-6k