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

2. Streptococcus Outline
Streptococcus Characteristics
Streptococcal Diseases

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

4. 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

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

6. 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

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

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

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

10. 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

11. 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

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

13. 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:

14. Streptococcal Suppuration

15. Puerperal Fever “Childbirth Fever” Membranes of genital tract ruptured
Semmelweis
Membranes of genital tract ruptured
fulminating septicemia
fatal 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

16. Post vaccination Streptococcal Infection

17. Streptococcal Cellulitis

18. Scarlet Fever

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

20. Scarlet Fever
Strawberry Tongue

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

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

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

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

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

26. Rheumatic Endocarditis
Scarred heart valves

27. 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

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

29. Streptococcal Antigens
Lancefield groups
M antigens
T antigens
R antigens

30. 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

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

32. 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

33. 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

34. 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

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

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

37. 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

38. S. pneumoniae

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

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

41. 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

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

43. 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

44. 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

45. The End