The genus streptococcus is comprised of many species of Gram positive cocci arranged in chains. These organisms are further divided into serologic subgroups called Lancefield groups designated by capital letters A, B, C etc. Streptococcus pneumoniae is also alpha-hemolytic but must not be confused with the viridans streptococci. The most important non-hemolytic streptococci are now not in the genus Streptococcus at all. This organism is one of the most important human pathogens and is responsible for a wide variety of clinical manifestations. Group specific carbohydrate is an integral part of the cell wall and is the moiety that is detected in Lancefield serotyping of beta-hemolytic Streptococci. Systemic Pyrogenic Exotoxins (SPEs) are produced by some strains and are responsible for the rash of scarlet fever. GAS is the only bacterium that causes significant pharyngitis in immunocompetent individuals. Scarlet fever is said to occur when GAS infection is accompanied by a, very characteristic, diffuse exanthem and enanthem. An infection of mainly the epidermis with significant lymphatic involvement, erysipelas is distinguished from cellulitis by its sharply demarcated, slightly raised borders. Impetigo is a benign but unsightly condition commonly affecting the face of children that manifests as honey-colored crusts of exudate on an erythematous base. Since about 1987 there has been an increase of severe GAS infections that are often rapidly progressive and have a high rate of mortality.
Though now very rare in industrialized countries, Rheumatic Fever is still a feared complication of GAS pharyngitis. Post Streptococcal Acute Glomerulonephritis (AGN) Characterized by edema, hypertension, hematuria and proteinuria approximately 2 weeks after a GAS infection, Post Streptococcal AGN is a fairly common complication of both pharyngitis and skin infections especially in children. Babies most at risk include those that are premature or are born to mothers with prolonged rupture of membranes. The genus Enterococcus includes organisms that are normal inhabitants of the human gut that were formerly included within the genus Streptococcus. Erythema Nodosum is a skin disorder in which red bumps are formed under the skin causing inflammation. The most prominent sign for identifying this disease is raised tender lesions or bumps on the layer of the skin, more particular in front part of the legs and below the knees. Since common insect bites also produces similar symptoms, it is essential to get it checked with your doctor to eliminate EN. Treatment should be oriented towards identifying the underlying cause of the disease and curing it.
Normally, Erythema Nodosum stays in the skin causing painful blisters for 3-6 weeks and gradually withers off. They are distinguished from the other major genus of Gram-positive cocci – Staphylococcus by their cellular arrangement and their inability to produce the enzyme catalase.

The two most important types of beta-hemolytic streptococci, by far, are Group A beta-hemolytic streptococcus (GAS) or Streptococcus pyogenes and Group B beta-hemolytic streptococcus (GBS) or Streptococcus agalactiae. They have been separated into the genus Enterococcus and have gained importance as pathogens in recent years.
The only reservoir is human beings and it may be found in a proportion of the oropharynges of healthy individuals referred to as carriers. It is a relatively infrequent cause accounting for approximately 10% of sore throats assessed in a physicians office, the majority of cases being viral in origin.
The rash is a generalized, fine raised red rash, prominent on the face and trunk and, late in its course, is said to feel like sandpaper. Commonly affecting the lower legs, especially in persons with chronically edematous extremities, it can occur on any part of the skin and is often associated with severe systemic toxicity.
Approximately two weeks after infection patients develop an acute inflammatory state with heart, joints, subcutaneous tissues and CNS bearing the brunt of the assault. Thought to immunologically mediated, it is usually self limited and fairly benign but may result in permanent renal damage requiring dialysis or transplantation. Though also involved in many kinds of infections in adults particularly in debilitated individuals, it is disease in newborns that is most important. This type of skin inflammation occurs only in specific fatty areas and not on other parts of the skin.
Very often it is found in association with certain infectins like Chlamydia, streptococcus, Hepatitis B infection, Cat scratch disease and Syphilis, Leptospirosis and mycobacterial infection.
The lesions may be painful and it may turn into purple color within few days of infection and finally turns brown before fading, leaving a small patch on the affected part. Punch biopsy is done in case the doctor finds it difficult to confirm the disease by examining the skin layer.
Infections similar to those caused by GAS are occasionally caused by Group C and G beta-hemolytic streptococci.
However, there are approximately 80 distinct M types and because immunity is type specific, repeat infections with different serotypes occur. Diagnostic microbiology laboratories restrict the processing of throat cultures to determining if GAS is present or not.
The distinction between the two may be difficult and is clinically moot as investigation and therapy are the same.
The effects of carditis with deformity of heart valves makes up the major long term morbidity associated with the condition. Strategies to identify pregnant women who are colonized with GBS and then treat them with intra-partum (during labor) antibiotics if risk factors are present has reduced the incidence of serious GBS disease and is an area of active research and controversy.
Until recent times they were viewed as relatively inconsequential, low virulence organisms that are involved mostly in mixed organism infections related to gut disruption.
This causes painful reddish lumps on the affected parts and is very often found in front portion of the legs and below the knees.
Sometimes, if the skin becomes sensitive to certain medications like penicillin, amoxicillin or sulfonamides, the skin may develop lumps causing inflammation.

Initially the lesions may be broad and raised but when it withers off from the skin it becomes flat to shrink down. In some cases, the doctor may ask you to do throat culture for eliminating streptococcus infection and an X-ray of the chest to rule out TB. This is generally a fairly mild self limiting illness, though local complications can occur e.g. Systemic pyrogenic exotoxins are responsible and disease is generally no more severe than GAS pharyngitis unaccompanied by Scarlet Fever rash. Diagnosis is made clinically using the revised (1992) Jones Criteria which state that Rheumatic Fever is highly likely if supported by evidence of a preceding GAS infection and the presence of two major OR one major and two minor manifestations. Existing disorders like leukemia, rheumatic fever, ulcer and Becheta€™s disease may cause Erythema Nodosum in some people. In case of chronic Erythema Nodosum, there may be other symptoms like fever, redness of the skin with irritation and general ill feeling. This is an excellent example of the need for extremely prudent antibiotic prescribing practices. Unlike other skin disorder, this type of nodular swelling exhibits a specific pattern thus easy to identify. However, it is the association of GAS pharyngitis with Rheumatic Fever that has made this illness far more important than it otherwise would be as discussed below. There were fears that a clone of GAS with increased virulence had re-emerged, was spreading and this was responsible for the change in epidemiology. The good thing about Erythema Nodosum (EN) is it will disappear on its own after few weeks, leaving only small scar on the infected area. However clinical microbiology laboratories generally do not have the ability (or the interest) to differentiate one species from the other. However, as with most infectious diseases, the circumstance seems considerably more complicated and organisms of many M types producing all three types of SPEs have now been implicated. Subacute Bacterial Endocarditis (SBE) is an infection of heart valves that is commonly caused by this group of organisms. This is the reason that people with abnormal heart valves are advised to receive prophylactic antibiotics prior to dental manipulation. Clinically, patients present with pain and systemic complaints disproportionate to their soft tissue infection.
They progress rapidly to shock and death without interventions in the form of aggressive surgical debridement and antibiotics.

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