Hugh B. Fackrell Filename:Strept.ppt Streptococcus Hugh B. Fackrell Filename:Strept.ppt

Streptococcus Outline Streptococcus Characteristics Streptococcal Diseases

Streptococcus: characteristics Genus definition Growth requirements Capsule Colonial morphology Hemolysis Destruction of RBCs Hemolysins molecules that destroy RBCs

Streptococcus Genus Definition Gram +ve cocci, chains or pairs Catalase -ve facultative anaerobes some strictly anaerobic some capnophilic (CO2) Ferment sugars to mixed acids and ethanol Lancefield group D is motile

Fastidious Most Streptococci are fastidious in their growth requirements Grow poorly on nutrient agar Grow well on blood agar

Capsule Made of hyaluronic acid: Non immunogenic polymer of glucuronic acid & N-acetylglucosamine Non immunogenic hyaluronic acid intercellular cement detected only in young(2-4 h) broth cultures bacteria produce hyaluronidase

Colonial Morphology GLOSSY: no capsule, colonies small MUCOID: capsule, colonies are large, glistening, viscous MATT:capsule, older colonies are dried, flatter rougher Glossy Mucoid

Two Forms of Hemolysis Beta Hemolysis Clearing Alpha Hemolysis Greening “viridans” Beta Hemolysis Clearing (Gamma hemolysis = no lysis)

Streptococcal Beta Hemolysis Two hemolysins Both cause clearing Both involved in disease

Hemolysin S (stable in air) Beta hemolysis on blood agar Do not develop antibodies Induces arthritis Two parts Carrier hemolysin polypeptide cell bound hemolysin lyses leukocytes and platelets stimulates release of lysosomal contents

Subsurface colony of Streptococcus producing Hemolysin 0 Hemolysin O Subsurface colony of Streptococcus producing Hemolysin 0 Oxidized in air oxygen labile (reversible) Protein Cardiotoxic patients develop antibodies ASOT cholesterol labile (irreversible) Antistreptolysin O test

Streptococcus pyogenes Suppurative Diseases Pharyngitis Scarlet Fever Erysipalas ( St. Antony’s fire) Cellulitis Puerperal Fever Sepsis Meningitis Pneumonia Subacute Bacterial Endocardititis Otitis Media

Diseases of S. pyogenes Pharyngitis: Scarlet fever: Pyoderma incubation period of 2 to 4 days sore throat, fever, malaise, headache Erythema of the pharynx cervical lymphadenopathy diagnosis -- differential -- viral pharyngitis Scarlet fever: all of the above plus red rash and red tongue Pyoderma Non-suppurative, inflammatory:

Streptococcal Suppuration

Puerperal Fever “Childbirth Fever” Membranes of genital tract ruptured Semmelweis Membranes of genital tract ruptured fulminating septicemia fatal 24-48 hr S. pyogenes 60-75% of cases Anaerobic streptococci 20-25% S. pyogenes Not isolated from vagina of healthy females before birth 50-60% from physician rest from own nose & throat

Post vaccination Streptococcal Infection

Streptococcal Cellulitis

Scarlet Fever

Scarlet Fever Rash Peticial hemorrhage Erythrogenic toxin Pin point Subcutaneous Erythrogenic toxin Scarletina toxin causes rash associated with a temperate phage

Scarlet Fever Strawberry Tongue

Schultz-Charlton test Inject 0.1 ml antitoxin subcutaneously Rash fades after 6-8 hours (possible delay 14 h) Differentiates from other similar rashes

Erysipalas Secondary invasion Skin reddened thickened minor original lesion Skin reddened thickened later purple Bacteria only in advancing edge

Erysipalas: butterfly rash common near nose spreads after 4-6 days Septicemia common complication No toxin No immunity repeated attacks possible

Rheumatic Fever autoimmune acute glomerulonephritis Acute, non suppurative post streptococcal inflammation Joints, heart valves,myocardium,nerves chorea- inflammation of nerves

Scarred heart valves reduced cardiac output heart failure Mitral valve stenosis edema, hypertension, hematuria and proteinuria

Rheumatic Endocarditis Scarred heart valves

Rheumatic fever latent period Latent period 2-4 weeks same after repeated infections not immunological Antibiotics taken during first week of pharyngeal infection Drop Steptococcal count Block rheumatic fever

Aschoff Bodies Inflammation of myocardium Mononuclear cell infiltration Granuloma-like nodules Characteristc of rheumatic fever

Streptococcal Antigens Lancefield groups M antigens T antigens R antigens

Streptococcus Lancefield Groups Rebecca Lancefield Grouped by presence of distinctive cell wall antigens Polysacchardies or glycero teichoic acids Antigens labelled A-T exclude I & J Group A Streptococci Clinically Important

Lancfield Groups S. pneumoniae N/A S.pyogenes -- Lancefield Group A S.agalactiae -- Lancefield Group B Enterococcus-Lancefield Group D Viridans group

Bacitracin sensitive Beta hemolytic Strept reported as Group A Strept Group A Streptococci S. pyogenes Group A clinically important Lancefield grouping time consuming Group A correlated with sensitivity to bacitracin Bacitracin sensitive Beta hemolytic Strept reported as Group A Strept

Group D Streptococci glycerol teichoic acid -- associated with the cytoplasmic membrane Streptococcus bovis, Enterococcus faecalis, Enterococcus faecium resist bile and high concentrations of sodium chloride Disease: urinary tract infection intra-abdominal abcesses wound infection Endocarditis

M antigens proteins of the pilus Involved in rheumatic fever sensitive to Pepsin & Trypsin soluble at pH 2 50 types Involved in rheumatic fever 5-8 types Antibodies neutralize streptococcal infections

Pathogenesis capsule -- non-immunogenic M Protein -- antiphagocytic, anticomplementary Lipoteichoic acid (LTA): mediates adherence to epithelial cells LTA binding protein Host cell membrane: Deacylated LTA

Enzymes Streptokinase A & B: DNA ase: Hyaluronidase: DPN ase lyse blood clots DNA ase: depolymerase DNA in pus Hyaluronidase: hyaluronic acid DPN ase

Lab diagnosis Gram stain -- good in cases of pyoderma fluorescent antibody detection of antibodies to Streptolysin O ASO 3-4 weeks after exposure Culture: swab the lesion directly blood agar plates - hemolysis Eliza

S. pneumoniae

Streptococcus pneumoniae Gram positive cocci in pairs, singles, short chains alpha hemolysis -- aerobic beta hemolysis -- anaerobic capsule -- immunogenic (84 serotypes)

Diseases: Pneumonia -- inflammation of the lungs with exudation and consolidation (solidification) Sinusitis Meningitis Bacteremia

Pathogenesis virulence factor, capsule -- prevents phagocytosis Pneumolysin is a temperate and oxygen labile hemolysin Purpura-producing principal is released during cell autolysis Neuraminidase -- glycoproteins and glycolipids Autolysins, amidases -- autolyse peptidoglycan layer

Mechanisms of Pathogenicity aspiration of S. pneumoniae, an endogenous oral organism organism colonizes the oropharynx epiglottal reflex, coughing is inhibited

Lobar Pneumoniae multiplication in the alveolar spaces viral infection frequently precedes bacterial infection highly invasive due to capsule bacteremia common Meningitis -- most often in children Treatment: Penicillin, Erythromycin

Laboratory Diagnosis sputum -- gram+ cocci, lancet shaped,capsule, may appear over-decolourized alpha-hemolytic, optochin sensitive Quellung reaction -- specific antiserum to capsular polysaccharide capsular antigen can be detected by very sensitive immunologic tests

The End