Group A Streptococcus - Streptococcus pyogenes
Streptococcus pyogenes is a gram-positive cocci bacteria which hemolyzes red blood cells in sheep blood agar. Members of the species typically exhibit this characteristic. Group A streptococcus is presumptively identified in the microbiology laboratory by this appearance on sheep blood agar. The organism is catalase-negative (it lacks the catalase enzyme which all staphylococci bacteria possess) and a positive PYR reaction (it possess the enzyme pyrrolidonylarylamidase - PYR - which is absent in staphylococci). Definitive biochemical tests are performed to confirm the isolation of group A streptococcus since it is know to cause serious complications described below. Group A streptococcus is the leading cause of acute bacterial pharyngitis/tonsillitis, or "strep throat" occurring worldwide. Strep throat is seen most commonly in children, but all ages may be infected by this bacteria. Acute bacterial pharyngitis occurs most commonly in the winter or spring and has an abrupt onset of symptoms which are sore throat, headache, high fever, and swollen cervical lymph nodes. If untreated or inadequately treated, pharyngitis caused by group A streptococcus can lead to rheumatic fever which affects the heart, and post acute streptococcal glomerulonephritis, a serious condition in which the kidneys loss their ability to function properly. Both conditions can be life-threatning, but are not seen at the same time in a patient. When the rash appears with the throat infection, the condition is referred to as scarlet fever.
Scarlet fever resembles strep pharyngitis, but the condition is accompanied by a skin rash that appears first on the upper chest and spreads to the trunk, neck, arms, and legs. The skin appears to be pealing as that seen in a severe sunburn. This, too, is a serious condition, and can progress to a necrotizing fasciitis if the infection spreads to the fascia, the protective covering which is underneath the skin. For more illustrations go to the streptococcal pharyngitis resource web page from the Medical Reference Library - Healthway Interactive. Click on the desired photograph for a larger view.
Streptococcus pyogenes is a gram-positive cocci bacteria which hemolyzes red blood cells in sheep blood agar. Members of the species typically exhibit this characteristic. Group A streptococcus is presumptively identified in the microbiology laboratory by this appearance on sheep blood agar. The organism is catalase-negative (it lacks the catalase enzyme which all staphylococci bacteria possess) and a positive PYR reaction (it possess the enzyme pyrrolidonylarylamidase - PYR - which is absent in staphylococci). Definitive biochemical tests are performed to confirm the isolation of group A streptococcus since it is know to cause serious complications described below. Group A streptococcus is the leading cause of acute bacterial pharyngitis/tonsillitis, or "strep throat" occurring worldwide. Strep throat is seen most commonly in children, but all ages may be infected by this bacteria. Acute bacterial pharyngitis occurs most commonly in the winter or spring and has an abrupt onset of symptoms which are sore throat, headache, high fever, and swollen cervical lymph nodes. If untreated or inadequately treated, pharyngitis caused by group A streptococcus can lead to rheumatic fever which affects the heart, and post acute streptococcal glomerulonephritis, a serious condition in which the kidneys loss their ability to function properly. Both conditions can be life-threatning, but are not seen at the same time in a patient. When the rash appears with the throat infection, the condition is referred to as scarlet fever.
Scarlet fever resembles strep pharyngitis, but the condition is accompanied by a skin rash that appears first on the upper chest and spreads to the trunk, neck, arms, and legs. The skin appears to be pealing as that seen in a severe sunburn. This, too, is a serious condition, and can progress to a necrotizing fasciitis if the infection spreads to the fascia, the protective covering which is underneath the skin. For more illustrations go to the streptococcal pharyngitis resource web page from the Medical Reference Library - Healthway Interactive. Click on the desired photograph for a larger view.
Sheep blood agar with colonies of beta-hemolytic group A streptococcusFlesh Eating Bacteria
Necrotizing fasciitis is a bacterial infection of the fibrous tissues that covers the body beneath the skin. It also covers the muscles of the body and serves as a protective covering. Fasciitis refers to an inflammation in the fascia which is a natural immune response due to bacterial infection or injury to the tissues. Necrotizing fasciitis is a serious condition and medical attention. should be sought immediately. Until recently this condition was rarely seen in Texas but sporadic has been seen in patients throughout the world including the US. This condition was once referred to as hospital gangene. Typically, two bacteria are implicated which are group A streptococcus and Staphylococcus aureus.
For more information on this "flesh eating bacteria" link to Communicable Disease Centers' National Center for Infectious Diseases or National Necrotizing Fasciitis Foundation (NNFF).
For more information on this "flesh eating bacteria" link to Communicable Disease Centers' National Center for Infectious Diseases or National Necrotizing Fasciitis Foundation (NNFF).
MMWR - link to the CDC's Morbidity and Mortality Weekly Report then use the searchable INDEX for case histories on fasciitis caused by group A strep.
Medical Tribune News Service Elderly at Risk for contracting "Flesh-eating Bacteria"
Group A Strep Page pictures..stories..links..survivor of this disease
Fact Sheet description of group A Streptococcal infections: NIH's National Institute of Allergy and Infectious Diseases
Streptococcus : Basic description of the streptococci from The Rockefeller University's Laboratory of Bacterial Pathogenesis and Immunology
Group A Strep descriptions of the various manifestations of streptococcal infections - Queens Hospital, London, England
Causes for sore throat other than group A streptococcus
Necrotizing Fasciitis links and a picture of this variant of group A strep causing acute necrotizing fasciitis on a leg **caution** don't got to this site if you have a weak stomach.
A View on The Flesh Eating Bacteria : group A streptococcus
Invasive Group A Streptococci : From Bug Bytes of John W, King, M.D. at the Infectious Disease Department, LSU Medical Center - Shreveport, LA.
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