Streptococcus pyogenes
S. pyogenes bacteria @ 900x magnification.
Scientific classification
Kingdom: Bacteria Phylum: Firmicutes Class: Bacilli Order: Lactobacillales Family: Streptococcaceae Genus: Streptococcus Species: S. pyogenes
Binomial name
Streptococcus pyogenes Rosenbach 1884

Streptococcus pyogenes is a spherical gram-positive bacteria that grows in long chains ^[1] and is the cause of Group A streptococcal infections. S. pyogenes displays group A antigen on its cell wall and beta-hemolysis when cultured on blood agar plate. S. pyogenes typically produces large zones of beta-hemolysis, the complete disruption of erythrocytes and the release of hemoglobin, and it is therefore called Group A (beta-hemolytic) Streptococcus (abbreviated GAS). Streptococci are catalase-negative. Image File history File links Download high resolution version (2470x2293, 2288 KB)Pappenheims stain of Streptococcus pyogenes bacteria @ 900x magnification. ... For other uses, see Scientific classification (disambiguation). ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Classes Bacilli Clostridia Mollicutes The Firmicutes are a division of bacteria, most of which have Gram-positive cell wall structure. ... Orders Bacillales Lactobacillales The term bacilli (singular bacillus) is used to refer to any rod-shaped bacteria. ... Families Aerococcaceae Carnobacteriaceae Enterococcaceae Lactobacillaceae Leuconostocaceae Streptococcaceae The Lactobacillales are an order of Gram-positive bacteria that comprise the lactic acid bacteria. ... Genera Lactococcus Lactovum Pilibacter Streptococcus The Streptococcaceae is a family of Gram-positive bacteria, placed within the order of Lactobacillales. ... Streptococcus is a genus of spherical shaped Gram-positive bacteria, belonging to the phylum Firmicutes[1] and the lactic acid bacteria group. ... This article does not cite any references or sources. ... Staphylococcus Cocci (singular - coccus, from the latin word kokkus meaning a berry) are any spherical or near spherical bacteria. ... Gram-positive bacteria are those that are stained dark blue or violet by gram staining, in contrast to gram-negative bacteria, which are not affected by the stain. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... The group A streptococcus bacterium (Streptococcus pyogenes, or GAS) is a form of Streptococcus bacteria responsible for most cases of streptococcal illness. ... Examples of alpha (top), beta (middle), and gamma (bottom) hemolysis on sheep blood agar plates Hemolysis is used in the empirical identification of microorganisms based on the ability of bacterial colonies grown on agar plates to break down red blood cells in the culture. ... Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ... Structure of hemoglobin. ... Streptococcus is a genus of spherical shaped Gram-positive bacteria, belonging to the phylum Firmicutes[1] and the lactic acid bacteria group. ...

Serotyping

In 1928, Rebecca Lancefield published a method for serotyping S. pyogenes based on its M protein, a virulence factor that is displayed on its surface.^[2] Later in 1946, Lancefield described the serologic classification of S. pyogenes isolates based on their surface T antigen.^[3] Four of the 20 T antigens have been revealed to be pili, which are used by bacteria to attach to host cells.^[4] Currently, over 100 M serotypes and approximately 20 T serotypes are known. Rebecca Craighill Lancefield (January 5, 1895 - March 3, 1981) was a prominent American microbiologist. ... Virulence refers to the degree of pathogenicity of a microbe, or in other words the relative ability of a microbe to cause disease. ... Image of bacteriological pili or fimbriae A pilus (Latin; plural : pili) is a hairlike structure on the surface of a cell, especially Gram-negative bacteria, a protein appendage required for bacterial conjugation. ...

Pathogenesis

Main article: Group A streptococcal infection

S. pyogenes is the cause of many important human diseases ranging from mild superficial skin infections to life-threatening systemic diseases. Infections typically begin in the throat or skin. Examples of mild S. pyogenes infections include pharyngitis ("strep throat") and localized skin infection ("impetigo"). Erysipelas and cellulitis are characterized by multiplication and lateral spread of S. pyogenes in deep layers of the skin. S. pyogenes invasion and multiplication in the fascia can lead to necrotizing fasciitis, a potentially life-threatening condition requiring surgical treatment. The group A streptococcus bacterium (Streptococcus pyogenes, or GAS) is a form of Streptococcus bacteria responsible for most cases of streptococcal illness. ... ÏŽ:For the noisegrind band, see Sore Throat. ... Fascia is specialized connective tissue layer which surrounds muscles, bones, and joints, providing support and protection and giving structure to the body. ... Necrotizing fasciitis or fasciitis necroticans, commonly known as flesh-eating bacteria, is a rare infection of the deeper layers of skin and subcutaneous tissues, easily spreading across the fascial plane within the subcutaneous tissue. ...

Infections due to certain strains of S. pyogenes can be associated with the release of bacterial toxins. Throat infections associated with release of certain toxins lead to scarlet fever. Other toxigenic S. pyogenes infections may lead to streptococcal toxic shock syndrome, which can be life-threatening. For other uses, see Toxin (disambiguation). ... Toxic shock syndrome (TSS) is a rare but potentially fatal disease caused by a bacterial toxin. ...

S. pyogenes can also cause disease in the form of post-infectious "non-pyogenic" (not associated with local bacterial multiplication and pus formation) syndromes. These autoimmune mediated complications follow a small percentage of infections and include rheumatic fever and acute poststreptococcal glomerulonephritis. Both conditions appear several weeks following the initial streptococcal infection. Rheumatic fever is characterised by inflammation of the joints and/or heart following an episode of Streptococcal pharyngitis. Acute glomerulonephritis, inflammation of the renal glomerulus, can follow Streptococcal pharyngitis or skin infection. Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. ... Rheumatic fever is an inflammatory disease which may develop after a Group A streptococcal infection (such as strep throat or scarlet fever) and can involve the heart, joints, skin, and brain. ... Glomerulonephritis, also known as glomerular nephritis and abbreviated GN, is a primary or secondary immune-mediated renal disease characterized by inflammation of the glomeruli, or small blood vessels in the kidneys. ... Rheumatic fever is an inflammatory disease which may develop after a Group A streptococcal infection (such as strep throat or scarlet fever) and can involve the heart, joints, skin, and brain. ... ÏŽ:For the noisegrind band, see Sore Throat. ... Glomerulonephritis, also known as glomerular nephritis and abbreviated GN, is a primary or secondary immune-mediated renal disease characterized by inflammation of the glomeruli, or small blood vessels in the kidneys. ... The kidneys are the organs that filter wastes (such as urea) from the blood and excrete them, along with water, as urine. ... Glomerulus refers to two unrelated structures in the body, both named for their globular form. ... ÏŽ:For the noisegrind band, see Sore Throat. ...

This bacterium remains acutely sensitive to penicillin. Failure of treatment with penicillin is generally attributed to other local commensal organisms producing β-lactamase or failure to achieve adequate tissue levels in the pharynx. Certain strains have developed resistance to macrolides, tetracyclines and clindamycin. For the Japanese rock band, see Penicillin (band). ... For the Japanese rock band, see Penicillin (band). ... The macrolides are a group of drugs (typically antibiotics) whose activity stems from the presence of a macrolide ring, a large lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, are attached. ... This article deals with the specific Tetracycline antibiotic. ... Clindamycin (rINN) (IPA: ) is a lincosamide antibiotic used in the treatment of infections caused by susceptible microorganisms. ...

Virulence factors

S. pyogenes has several virulence factors that enable it to attach to host tissues, evade the immune response, and spread by penetrating host tissue layers.^[5] A carbohydrate capsule composed of hyaluronic acid surrounds the bacterium, protecting it from phagocytosis by neutrophils. In addition, the capsule and several factors embedded in the cell wall, including M protein, lipoteichoic acid, and protein F (SfbI) facilitate attachment to various host cells.^[6] M protein also inhibits opsonization by the alternative complement pathway by binding to host complement regulators. M protein found on some serotypes are also able to prevent opsonization by binding to fibrinogen. However, the M protein is also the weakest point in this pathogen's defense as antibodies produced by the immune system against M protein target the bacteria for engulfment by phagocytes. M proteins are unique to each strain, and identification can be used clinically to confirm the strain causing an infection. Virulence refers to the degree of pathogenicity of a microbe, or in other words the relative ability of a microbe to cause disease. ... Lactose is a disaccharide found in milk. ... Hyaluronan (also called hyaluronic acid or hyaluronate) is a glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues. ... Steps of a macrophage ingesting a pathogen: a. ... Neutrophil granulocytes (commonly referred to as neutrophils) are a class of white blood cells and are part of the immune system. ... Lipoteichoic acid (LTA) is a surface-associated adhesion amphiphile from Gram-positive bacteria and regulator of autolytic wall enzymes (muramidases). ... An opsonin is any molecule that acts as a binding enhancer for the process of phagocytosis. ... A complement protein attacking an invader. ... Fibrin is a protein involved in the clotting of blood. ... Each antibody binds to a specific antigen; an interaction similar to a lock and key. ... A scanning electron microscope image of a single neutrophil (yellow), engulfing anthrax bacteria (orange). ... A phagocyte is a cell that ingests (and destroys) foreign matter, such as microorganisms or debris via a process known as phagocytosis, in which these cells ingest and kill offending cells by cellular digestion. ...

S. pyogenes releases a number of proteins, including several virulence factors, into its host:

Streptolysin O and S

These are toxins which are the basis of the organism's beta-hemolytic property. Streptolysin O is a potent cell poison affecting many types of cell including neutrophils, platelets, and sub-cellular organelles. It causes an immune response and detection of antibodies to it; antistreptolysin O (ASO) can be clinically used to confirm a recent infection.

Streptococcal pyrogenic exotoxins (Spe) A and C

SpeA and SpeC are superantigens secreted by many strains of S. pyogenes. These pyrogenic exotoxins are responsible for the rash of scarlet fever and many of the symptoms of streptococcal toxic shock syndrome.

Streptokinase

Enzymatically activates plasminogen, a proteolytic enzyme, into plasmin which in turn digests fibrin and other proteins.

Hyaluronidase

It is widely assumed that hyaluronidase facillitates the spread of the bacteria through tissues by breaking down hyaluronic acid, an important component of connective tissue. However, very few isolates of S. pyogenes are capable of secreting active hyaluronidase due to mutations in the gene that encode the enzyme. Moreover, the few isolates that are capable of secreting hyaluronidase do not appear to need it to spread through tissues or to cause skin lesions.^[7] Thus, the true role of hyaluronidase in pathogenesis, if any, remains unknown.

Streptodornase

Most strains of S. pyogenes secrete up to four different DNases, which are sometimes called streptodornase. The DNases protect the bacteria from being trapped in neutrophil extracellular traps (NETs) by digesting the NET's web of DNA, to which are bound neutrophil serine proteases that can kill the bacteria.^[8]

C5a peptidase

C5a peptidase cleaves a potent neutrophil chemotaxin called C5a, which is produced by the complement system.^[9] C5a peptidase is necessary to minimize the influx of neutrophils early in infection as the bacteria are attempting to colonize the host's tissue.^[10].

Streptococcal chemokine protease

The affected tissue of patients with severe cases of necrotizing fasciitis are devoid of neutrophils.^[11]. The serine protease ScpC, which is released by S. pyogenes, is responsible for preventing the migration of neutrophils to the spreading infection.^[12] ScpC degrades the chemokine IL-8, which would otherwise attract neutrophils to the site of infection. C5a peptidase, although required to degrade the neutrophil chemotaxin C5a in the early stages of infection, is not required for S. pyogenes to prevent the influx of neutrophils as the bacteria spread through the fascia.^[10][12]

An exotoxin is a soluble chemical excreted by a microorganism, including bacteria, fungi, algae, and protozoa. ... An exotoxin is a soluble chemical excreted by a microorganism, including bacteria, fungi, algae, and protozoa. ... SEB, A typical bacterial superantigen (PDB:3SEB) The β-grasp domain is shown in red, and the β-barrel in green: The disulphide loop is shown in yellow SEC3 (yellow) complexed with an MHC-II molecule (green & cyan): The SAgs binds adjacent to the antigen (purple) presentation cleft in the MHC-II... A rash is a change in skin which affects its color, appearance, or texture. ... Toxic shock syndrome (TSS) is a rare but potentially fatal disease caused by a bacterial toxin. ... Streptokinase is an extracellular metallo-enzyme produced by beta-haemolytic streptococcus and is used as an effective and cheap clot-dissolving medication in some cases of myocardial infarction (heart attack) and pulmonary embolism. ... Plasmin is an important degrading enzyme (EC 3. ... Plasmin is an important degrading enzyme (EC 3. ... Fibrin is a protein involved in the clotting of blood. ... Hyaluronidase The hyaluronidases (EC 3. ... Hyaluronidase The hyaluronidases (EC 3. ... Hyaluronan (also called hyaluronic acid or hyaluronate) is a glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues. ... Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, muscle, and nervous tissue. ... A deoxyribonuclease (DNase, for short) is any enzyme that catalyzes the hydrolytic cleavage of phosphodiester linkages in the DNA backbone. ... A neutrophil extracellular trap is a set of extracellular fibres generated by a neutrophil that bind Gram positive and Gram negative bacteria. ... Neutrophil granulocytes (commonly referred to as neutrophils) are a class of white blood cells and are part of the immune system. ... Crystal structure of Trypsin, a typical serine protease. ... C5a is a protein fragment released from complement component C5. ... Peptidases (proteases [pronounced pro-tea-aces] and proteolytic enzymes are also commonly used) are enzymes which break peptide bonds of proteins. ... Neutrophil granulocytes (commonly referred to as neutrophils) are a class of white blood cells and are part of the immune system. ... C5a is a protein fragment released from complement component C5. ... Necrotizing fasciitis or fasciitis necroticans, commonly known as flesh-eating bacteria, is a rare infection of the deeper layers of skin and subcutaneous tissues, easily spreading across the fascial plane within the subcutaneous tissue. ... Neutrophil granulocytes (commonly referred to as neutrophils) are a class of white blood cells and are part of the immune system. ... Crystal structure of Trypsin, a typical serine protease. ... Chemokines are a family of pro-inflammatory activation-inducible cytokines, or small protein signals secreted by cells. ... Interleukin-8 (IL-8) is a chemokine produced by macrophages and other cell types such as epithelial cells. ... Neutrophil granulocytes (commonly referred to as neutrophils) are a class of white blood cells and are part of the immune system. ... Fascia is specialized connective tissue layer which surrounds muscles, bones, and joints, providing support and protection and giving structure to the body. ...

Diagnosis

Usually, a rectal swab is taken to the laboratory for testing. A Gram stain is performed to show Gram positive, cocci, in chains. Then, culture the organism on blood agar with added bacitracin antibiotic disk to show beta-haemolytic colonies and sensitivity (zone of inhibition around the disk) for the antibiotic. Then, perform catalase test, which should show a negative reaction for all Streptococci. S. pyogenes is cAMP and hippurate tests negative. Serological identification of the organism involves testing for the presence of group A specific polysaccharide in the bacterium's cell wall using the Phadebact test. As a precautionary measure tests are also carried out to check for illnesses including, but not limited to, Syphilis, and Avascular Necrosis. Gram staining is a method for staining samples of bacteria that differentiates between the two main types of bacterial cell wall. ... An agar plate is a sterile Petri dish that contains agar plus nutrients, and is used to culture bacteria or fungi. ... A tube of bacitracin ointment for eyes Bacitracin is a mixture of related cyclic polypeptides produced by organisms of the licheniformis group of Bacillus subtilis var Tracy. ... Examples of alpha (top), beta (middle), and gamma (bottom) hemolysis on sheep blood agar plates Hemolysis is used in the empirical identification of microorganisms based on the ability of bacterial colonies grown on agar plates to break down red blood cells in the culture. ... Catalase (human erythrocyte catalase: PDB 1DGF, EC 1. ... Hippuric acid (Gr. ... Syphilis is a curable sexually transmitted disease caused by the Treponema pallidum spirochete. ... Avascular necrosis is a disease resulting from the temporary or permanent loss of the blood supply to the bones. ...

Treatment

The treatment of choice is penicillin, however in the absence of readily available penicillin, small incisions made to the infected area will relieve swelling and discomfort until proper medical assistance can be sought. There is no reported instance of penicillin-resistance reported to date, although since 1985 there have been many reports of penicillin-tolerance.^[13] For the Japanese rock band, see Penicillin (band). ...

Macrolides, chloramphenicol, and tetracyclines may be used if the strain isolated has been shown to be sensitive, but resistance is much more common. The macrolides are a group of drugs (typically antibiotics) whose activity stems from the presence of a macrolide ring, a large lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, are attached. ... Chloramphenicol is a bacteriostatic antibiotic originally derived from the bacterium Streptomyces venezuelae, isolated by David Gottlieb, and introduced into clinical practice in 1949. ... Tetracycline (INN) (IPA: ) is a broad-spectrum antibiotic produced by the streptomyces bacterium, indicated for use against many bacterial infections. ...

References

Other reading

• Gladwin, Mark and Bill Trattler. Clinical Microbiology Made Ridiculously Simple, 3rd edition, 2004.
• Brooks, Geo F., Janet S. Butel, and Stephen A. Morse. Jawetz, Melnick, and Adelberg's Medical Microbiology, 22nd edition, 2001.