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Streptococcal Serology. Terry Kotrla. Introduction. Gram-positive Beta hemolytic Spherical, ovoid or lancet shaped Pairs or chains. Divided into Serotypes or groups. Two major outer proteins M and T Eighteen interior proteins knows as Lancefield grouping
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Streptococcal Serology Terry Kotrla
Introduction • Gram-positive • Beta hemolytic • Spherical, ovoid or lancet shaped • Pairs or chains
Divided into Serotypes or groups • Two major outer proteins M and T • Eighteen interior proteins knows as Lancefield grouping • Streptococcus pyogenes belong to Lancefield group A • M protein chief virulent factor
Numerous Exoantigens • Exoantigens are produced and excreted and include: • Streptolysin O • Dnase • Hyaluronidase • Nicotinamide Adenine Dinucleotidase • Streptokinase • Patients react to exoantigens by producing antibodies
Characteristics • Two major sites of infection • Upper respiratory tract • Skin • If infections left untreated can lead to post-streptococcal sequelae • Acute glomerulonephritis • Rheumatic fever
Upper Respiratory • Sore Throat • Tonsillar exudate • Fever • Chills • 20% school children carriers
Skin • Impetigo • Lesions on extremities • Commonly on face • Pustular and crusty
Suppurative Complications • Suppurate -To generate pus; as, a boil or abscess suppurates. • Erysipelas • Necrotizing fasciitis • Scarlet fever
Erysipelas • Infection involves the dermis and lymphatics and is a more superficial subcutaneous infection of the skin than cellulitis. • characterized by intense erythema, induration and a sharply demarcated border.
Scarlet Fever • Strep bacteria produces a toxin that causes a rash • Sandpapery • Peels
Non-Suppurative • Inflammatory response elsewhere in the body. • Damaging sequelae to strep infection • Rheumatic Fever • Post-Streptococcal glomerulonephritis
Rheumatic Fever • Delayed consequence of an untreated upper respiratory infection with group A streptococci • Causes serious, debilitating damage to the heart. • Associated with large amount of M protein and a capsule • Due to immune response against Strep antigens similar to heart antigens.
Rheumatic Fever This is the heart of a 44 year old woman who had rheumatic fever and had been treated for congestive heart failure for about one year.
Poststreptococcal glomerulonephritis • Follows strep infection of skin or pharynx • Characterized by damage to glomeruli of kidneys • Deposition of Ag-Ab complexes, activation of complement. • Inflammatory response causes damage.
Poststreptococcal glomerulonephritis • Most common in children 2-12 • Symptoms: • Hematuria • Proteinuria • Edema • hypertension
Poststreptococcal glomerulonephritis • The scattered capillary wall granular deposits in acute poststreptococcal glomerulonephritis also stain for complement (immunofluorescence with antibody to C3)
Laboratory Testing • Culture and identification • Rapid Strep Tests from throat swab • Detection of Streptococcal antibodies • Anti-Streptolysin O (ASO) titer