ASO

1ANTI STREPTOLYSIN O(ASO/ASLO)Presenter :- Rahul PrabhasModerator :- Dr. Varsha A Singh12ANTI STREPTOLYSIN O

2Family LysinToxins produced by various bacteria.Chemically protein in natureActivated by Sulphydrl compounds[ It is anorgano sulfur compoundthat contains a carbon bondedsulfhydryl(CSH or RSH) group] Inhibited by Cholesterol and related sterols like ergosterol(It is suggested that the inhibition of haemolysis is due to complex formation between the lysin and the sterol molecules when the latter are orientated at the interface, and that the lysis of red cells by streptolysin 0 is dependent on complex formation between the lysin and the cholesterol with resultant penetration of the surface film.)3StreptolysinProduced by Streptococcus bacteria

lysinsStreptolysin O(SLO)

Streptolysin S (SLS)4Types of streptolysinSLOProduced by group A StreptococciOxygen labile.AntigenicInhibited by cholesterolHaemolysis only in presence of OxygenSLSProduced by Streptococci agalactiaeOxygen stable.Nonantigenic - very small size.Inhibited by serum lipoproteinHaemolysis irrespective to the presence of Oxygen 56 SLO

Streptococccus pyogens Human pathogen7

Cell wall of Streptococcus pyogenes

8Structure of SLO9

PARTS OF SLO MOLECULE10Action Of SLO

11Mechanism of membrane damaging by streptolysin O12 water soluble toxin molecule bind to cholesterol of target membrane to assemble into supramolecular rod shapedThis supramolecular rod penetrates into the polar domain of the membrane bilayer.

Embedment of ring and arc generates trans membrane slit or pores(30 nm).Finally, it leads to damage of the plasma membrane.

SLO acts on following targetsCell Membranes of - Endothelial cells.Lymphocytes.Erythrocytes.Leukocytes.13Effect of streptolysin O on different types of cells in bodyEndothelial cell- Streptolysin O activates bone marrow derived mast cells to degranulate & to rapidly induce or enhance the production of several cytokines mRNA including TNF alpha. Mast cells derived TNF alpha plays an important protective role in acute inflammation.

Leukocytes- It enhances polymorphonuclear binding to gelatin matrix. It stimulates PMNL- dependent adherence mechanism.

Lymphocyte- It results in decrease lymphokines producton . Thus it alters the immune system.1414ANTI-STREPTOLYSIN OASO/ASLO

Antibodies made against SLO

Todd (1932) developed the assay for ASO antibodies.

15Detection MethodANTI-STREPTOLYSIN O TEST

Neutralization Method.

Latex Agglutination Method.

ELISA.1617Neutralization TestNeutralization TestHomologous Abs - prevents biological effect of toxin.

Infection with S.pyogens results in Abs against bacterial haemolysin appearing in serum.

Abs detected by incubating serum with standard amounts of active haemolysin when RBCs are added to mixture.18Latex Agglutination Slide TestPolystyrene latex particles are coated with purified and stabilized SLO(Ag),which reacts with its corresponding ASO(Ab) resulting in agglutination of latex particles.Two types:-

Qualitative Slide Test

Semi-Quantitative Slide Test1920

1. ASO Latex Reagent2. Positive Control Serum3. Negative Control SerumGlass slide20 Latex agglutination testPrincipleStreptolysin antigen + mono specific anti-streptolysin o

Agglutination

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Semiquantitave

Rapid latex slide test

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INTERPRETATIONPOSITIVE - Agglutination in 2minutes, ASO titre >200 IU/ml.

NEGATIVE No agglutination, ASO titre = 400 mg/dl, - recent infection and should be treated.

2526After medication course, carry ASO test again to be NEGATIVE, and confirmatory test called anti-DNase B test. - If negative, then the body is completely cured.

ASO titre test have high accuracy but to be assured of Streptococcal infection, a throat swab can be tested (cultured), results come after 2 4 days after culturing the sample.CLINICAL SIGNIFICANCERaised or rising levels Past or present infection

Historically, first bacterial markers used for diagnosis and follow up of rheumatic fever.

27 DISEASES IN WHICH ASO IS ELEVATEDSUPPURATIVE INFECTIONSPharyngitisPyoderma and streptococcal skin infectionsScarlet fever

NON SUPPURATIVE INFECTIONRheumatic feverHighest titre- >200 Todd unitsAcute Post-streptococcal GlomerulonephritisBacterial Endocarditis

28Pharyngitis

29Pyoderma Erysipelas

30Pyoderma Impetigo

31Scarlet fever

3233THANK YOU