1 Streptococcus Hugh B Fackrell Filename Strept ppt

1 Streptococcus Hugh B. Fackrell Filename: Strept. ppt 9/15/2020

2 Streptococcus Outline ä Streptococcus Characteristics ä Streptococcal Diseases 9/15/2020

3 Streptococcus: characteristics ä Genus definition ä Growth requirements ä Capsule ä Colonial morphology ä Hemolysis ä Destruction of RBCs ä Hemolysins ä molecules that destroy RBCs 9/15/2020

4 Streptococcus Genus Definition ä Gram +ve cocci, chains or pairs ä Catalase -ve facultative anaerobes ä some strictly anaerobic ä some capnophilic (CO 2) ä Ferment sugars to mixed acids and ethanol ä Lancefield group D is motile 9/15/2020

5 Fastidious ä Most Streptococci are fastidious in their growth requirements ä Grow poorly on nutrient agar ä Grow well on blood agar 9/15/2020

6 Capsule ä Made of hyaluronic acid: ä polymer of glucuronic acid & N -acetylglucosamine ä Non immunogenic ä hyaluronic acid intercellular cement ä detected only in young(2 -4 h) broth cultures ä bacteria produce hyaluronidase 9/15/2020

7 Colonial Morphology ä GLOSSY: no capsule, colonies small ä MUCOID: capsule, colonies are large, glistening, viscous ä MATT: capsule, older colonies are dried, flatter rougher Glossy Mucoid 9/15/2020

8 Two Forms of Hemolysis Alpha Hemolysis Greening “viridans” Beta Hemolysis Clearing (Gamma hemolysis = no lysis) 9/15/2020

9 Streptococcal Beta Hemolysis ä Two hemolysins ä Both cause clearing ä Both involved in disease 9/15/2020

10 Hemolysin S (stable in air) ä Beta hemolysis on blood agar ä Do not develop antibodies ä Induces arthritis ä Two parts ä Carrier ä hemolysin polypeptide ä cell bound hemolysin ä lyses leukocytes and platelets ä stimulates release of lysosomal contents 9/15/2020

11 Hemolysin O ä Oxidized in air ä oxygen labile (reversible) ä Protein ä Cardiotoxic ä patients develop antibodies ä ASOT ä cholesterol labile (irreversible) Subsurface colony of Streptococcus producing Hemolysin 0 ä Antistreptolysin O test 9/15/2020

12 Streptococcus pyogenes Suppurative Diseases ä ä ä ä Pharyngitis Scarlet Fever Erysipalas ( St. Antony’s fire) Cellulitis Puerperal Fever Sepsis Meningitis Pneumonia ä ä Subacute Bacterial Endocardititis Otitis Media 9/15/2020

13 Diseases of S. pyogenes ä Pharyngitis: ä ä ä incubation period of 2 to 4 days sore throat, fever, malaise, headache Erythema of the pharynx cervical lymphadenopathy diagnosis -- differential -- viral pharyngitis ä Scarlet fever: ä ä all of the above plus red rash and red tongue Pyoderma ä Non-suppurative, inflammatory: 9/15/2020

14 Streptococcal Suppuration 9/15/2020

15 Puerperal Fever ä “Childbirth Fever” ä ä Membranes of genital tract ruptured ä ä ä Semmelweis fulminating septicemia fatal 24 -48 hr S. pyogenes 60 -75% of cases ä ä S. pyogenes Not isolated from vagina of healthy females before birth ä ä 50 -60% from physician rest from own nose & throat Anaerobic streptococci 20 -25% 9/15/2020

16 Post vaccination Streptococcal Infection 9/15/2020

17 Streptococcal Cellulitis 9/15/2020

18 Scarlet Fever 9/15/2020

19 Scarlet Fever Rash ä Peticial hemorrhage ä Pin point ä Subcutaneous ä Erythrogenic toxin ä Scarletina toxin ä causes rash ä associated with a temperate phage 9/15/2020

20 Scarlet Fever Strawberry Tongue 9/15/2020

21 Schultz-Charlton test ä Inject 0. 1 ml antitoxin subcutaneously ä Rash fades after 6 -8 hours (possible delay 14 h) ä Differentiates from other similar rashes 9/15/2020

22 Erysipalas ä Secondary invasion ä minor original lesion ä Skin reddened thickened ä later purple ä Bacteria only in advancing edge 9/15/2020

23 Erysipalas: butterfly rash ä Butterfly rash ä common near nose ä spreads after 4 -6 days ä Septicemia common complication ä No toxin ä No immunity ä repeated attacks possible 9/15/2020

24 Rheumatic Fever ä autoimmune ä acute glomerulonephritis ä Acute, non suppurative ä post streptococcal inflammation ä Joints, heart valves, myocardium, nerves ä chorea- inflammation of nerves 9/15/2020

25 Scarred heart valves reduced cardiac output ä heart failure ä Mitral valve stenosis ä ä edema, hypertension, hematuria and proteinuria 9/15/2020

26 Rheumatic Endocarditis Scarred heart valves 9/15/2020

27 Rheumatic fever latent period ä Latent period 2 -4 weeks ä same after repeated infections ä not immunological ä Antibiotics taken during first week of pharyngeal infection ä Drop Steptococcal count ä Block rheumatic fever 9/15/2020

28 Aschoff Bodies ä Inflammation of myocardium ä Mononuclear cell infiltration ä Granuloma-like nodules ä Characteristc of rheumatic fever 9/15/2020

29 Streptococcal Antigens ä Lancefield groups ä M antigens ä T antigens ä R antigens 9/15/2020

30 Streptococcus Lancefield Groups ä Rebecca Lancefield ä Grouped by presence of distinctive cell wall antigens ä Polysacchardies or glycero teichoic acids ä Antigens labelled A-T ä exclude I & J ä Group A Streptococci Clinically Important 9/15/2020

31 Lancfield Groups ä S. pneumoniae N/A ä S. pyogenes -- Lancefield Group A ä S. agalactiae -- Lancefield Group B ä Enterococcus-Lancefield Group D ä Viridans group 9/15/2020

32 Group A Streptococci ä S. pyogenes Group A ä clinically important ä Lancefield grouping time consuming ä Group A correlated with sensitivity to bacitracin Bacitracin sensitive Beta hemolytic Strept reported as Group A Strept 9/15/2020

33 Group D Streptococci ä glycerol teichoic acid - associated with the cytoplasmic membrane ä ä Streptococcus bovis, Enterococcus faecalis, Enterococcus faecium resist bile and high concentrations of sodium chloride ä Disease: ä ä urinary tract infection intra-abdominal abcesses wound infection Endocarditis 9/15/2020

34 M antigens ä proteins of the pilus ä sensitive to Pepsin & Trypsin ä soluble at p. H 2 ä 50 types ä Involved in rheumatic fever ä 5 -8 types ä Antibodies neutralize streptococcal infections 9/15/2020

35 Pathogenesis ä capsule -- non-immunogenic ä M Protein -- antiphagocytic, anticomplementary ä Lipoteichoic acid (LTA): ä mediates adherence to epithelial cells ä LTA binding protein ä Host cell membrane: ä Deacylated LTA 9/15/2020

36 Enzymes ä Streptokinase A & B: ä lyse blood clots ä DNA ase: ä depolymerase DNA in pus ä Hyaluronidase: ä hyaluronic acid ä DPN ase 9/15/2020

37 Lab diagnosis ä Gram stain -- good in cases of pyoderma ä fluorescent antibody ä detection of antibodies to Streptolysin O ASO ä 3 -4 weeks after exposure ä Culture: ä swab the lesion directly ä blood agar plates - hemolysis ä Eliza 9/15/2020

38 S. pneumoniae 9/15/2020

39 Streptococcus pneumoniae ä Gram positive cocci in pairs, singles, short chains ä alpha hemolysis -- aerobic ä beta hemolysis -- anaerobic ä capsule -- immunogenic (84 serotypes) 9/15/2020

40 Diseases: ä Pneumonia -- inflammation of the lungs with exudation and consolidation (solidification) ä Sinusitis ä Meningitis ä Bacteremia 9/15/2020

41 Pathogenesis ä virulence factor, capsule -- prevents phagocytosis ä Pneumolysin is a temperate and oxygen labile hemolysin ä Purpura-producing principal is released during cell autolysis ä Neuraminidase -- glycoproteins and glycolipids ä Autolysins, amidases -- autolyse peptidoglycan layer 9/15/2020

42 Mechanisms of Pathogenicity ä aspiration of S. pneumoniae, an endogenous oral organism ä organism colonizes the oropharynx ä epiglottal reflex, coughing is inhibited 9/15/2020

43 Lobar Pneumoniae ä multiplication in the alveolar spaces ä viral infection frequently precedes bacterial infection ä highly invasive due to capsule ä bacteremia common ä Meningitis -- most often in children ä Treatment: ä Penicillin, Erythromycin 9/15/2020

44 Laboratory Diagnosis ä sputum -- gram+ cocci, lancet shaped, capsule, may appear overdecolourized ä alpha-hemolytic, optochin sensitive ä Quellung reaction -- specific antiserum to capsular polysaccharide ä capsular antigen can be detected by very sensitive immunologic tests 9/15/2020

45 The End 9/15/2020