2. STREPTOCOCCUS
&
ENTEROCOCCUS

3. REVIEW Bacterial Cell Morphology Gram Stain
Cytoplasmic (plasma) membrane
Cell wall structure
Bacterial cell shapes

5. Common Cell Membrane

6. Gram-Positive Cell Wall

7. Peptidoglycan
Gram-Negative
Gram-Positive

8. Gram-Positive Cell Wall
Teichoic Acid

9. Gram-Negative Cell Wall

10. Gram-Negative Cell Wall

15. Genus Streptococcus Commensals or Parasites of man & animals
Saprophytes of decaying matter
Morphology
Gram-Positive Cocci in Pairs or Chains

16. Gram-Positive
Streptococcus

17. Genus Streptococcus Physiology & Metabolism Facultative Anaerobes
Fastidious Growth Requirements
Fermentative Metabolism of Carbohydrates:
Lactic acid, ethanol, acetate endproducts produced; No gas
Catalase Negative (2H2O2 ---> O2 + 2H2O)
Separation of streptococci from staphylococci
Oxidase Negative (oxidoreductase oxidizes substrate w/ O2)
Beta, Alpha, or Gamma Hemolysis on blood agar

21. Genus Streptococcus Rebecca Lancefield
Developed useful serogrouping system
Classification of beta-hemolytic streptococci by group-specific cell wall carbohydrate (CHO) antigen
As of 1992, Serogroups A to H and K to V
Groups A, B, C, D, and G are most
comonly associated with human disease
Viridans streptococci and
Streptococcus pneumoniae have
no group-specific antigen

22. Streptococcus pyogenes (Group A)
Antigenic Structure
Streptococcus pyogenes (Group A)
Lancefield Group-specific antigen (C polysaccharide)
Complex polysaccharide in cell wall
Proteins: Two major classes, M & T antigens
Two minor classes, R & F
M-Protein: Type-specific antigen
Fimbriae-like, hairy extensions
Resistant to heat and acid
Trypsin Sensitive
Specific adherence by lipoteichoic acid and M-protein
(LTA-M) complexes

24. Streptococcus pyogenes (Group A)
Antigenic Structure
Streptococcus pyogenes (Group A)
Lancefield Group-specific antigen (C polysaccharide)
Complex polysaccharide in cell wall
Proteins: Two major classes, M & T antigens
Two minor classes, R & F
M-Protein: Type-specific antigen
Fimbriae-like, hairy extensions
Resistant to heat and acid
Trypsin Sensitive
Specific adherence by lipoteichoic acid and M-protein (LTA-M) complexes
T Antigens (not virulence factor)
Resistant to trypsin, heat and acid;
Adjunct to M-typing; Routine surveillance
Others

25. Antigenic Structure (cont.) Streptococcus pyogenes (Group A)
Capsular Polysaccharide:
Hyaluronic acid
Not present in all strains
Same as host hyaluronic acid (cartilage,skin etc)
Nonimmunogenic
Antiphagocytic
Hyaluronidase (cell wall division) during late growth
Lipoteichoic Acid

26. Lancefield Serogroup Classification of Beta-Hemolytic Streptococci Important in Human Disease
Group A Streptococci:
Streptococcus pyogenes
One of Most Important Human Pathogens
Suppurative Diseases:
Pharyngitis; Scarlet Fever;
Cutaneous & Soft Tissue Infections
Systemic Disease
Non-Suppurative Sequelae:ARF,RHD,AG

27. Streptococcus pyogenes
(Phase Contrast)

28. Lancefield Serogroup Classification of Beta-Hemolytic Streptococci Important in Human Disease (cont.)
Group B Streptococci:
Streptococcus agalactiae
Neonatal disease & obstetric complications
Systemic, Cutaneous, UTI's

29. Streptococcus agalactiae

30. Lancefield Classification of Beta-Hemolytic Streptococci (cont.)
Group C Streptococci: Pharyngitis
Enterococcus & Group D Streptococci
Genitourinary Tract Infections (UTIs)
Endocarditis
Group G Streptococci:
S.anginosus-milleri grp; Streptococcus spp.
Pharyngitis
Non-Lancefield Group Streptococci
Viridans Streptococci
Dental Caries: Streptococcus mutans
Streptococcus sanguis; Streptococcus salivarius; Streptococcus mitis
Streptococcus pneumoniae

31. Major Human Diseases of
Beta-Hemolytic Streptococci
Group A Streptococcus (S. pyogenes):
Diverse group of acute suppurative (pus-forming) & nonsuppurative diseases
Suppurative Streptococcal Diseases
Pharyngitis (& tonsilitis):
Scarlet fever: Complication of streptococcal pharyngitis when infecting strain is lysogenized; Frequently develop scarletina rash on upper chest spreading to extremities
Cutaneous & Soft Tissue Infxns.
Pyoderma (Impetigo: contagious pyoderma with superficial yellow weeping lesions)
Erysipelas: Acute superficial cellulitis of skin with lymphatic involvement; face and lower extremities, skin and subcutaneous tissues

32. Erysipelas
NOTE:
erythema
bullae

33. Major Human Diseases of Group A Streptococcus (S. pyogenes)
Beta-Hemolytic Streptococci (cont.)
Group A Streptococcus (S. pyogenes)
Suppurative Streptococcal Diseases
Cutaneous & Soft Tissue Infxns(cont.)
Cellulitis: Involvement of deeper subcutaneous tissues; Deeper invasion with systemic symptoms
Necrotizing fasciitis: (a.k.a., “flesh-eating bacteria”): Infection deep in subcutaneous tissues that spreads along fascial planes, destroying muscle and fat; Initially cellulitis followed by bullae (fluid filled blisters; bulla is singular), gangrene, systemic toxicity, multiorgan failure and mortality in more than 50% of patients
Wound Infections

34. Suppurative Streptococcal Diseases Group A Streptococcus (cont.)
Other Suppurative Diseases
Puerperal & neonatal sepsis
Lymphangitis: Inflammation of lymphatic vessel(s)
Pneumonia
Systemic Disease
Streptococcal Toxic Shock
Syndrome (TSS): Multisystem toxicity following soft tissue infection progressing to shock and organ failure (not to be confused with Staphylococcal Toxic Shock Syndrome where hyperabsorbent tampons have been identified as an important risk factor)
Bacteremia

35. Group A Streptococcal Diseases (cont.)
Nonsuppurative Sequelae
Post-infection complications of Group A streptococcal disease; Serious complications in pre-antibiotic era; still important in developing countries
Acute rheumatic fever (ARF):
Inflammation of heart, joints, blood vessels, sub- cutaneous tissues
Rheumatic heart disease (RHD):
Chronic, progressive heart valve damage
Acute glomerulonephritis (AG):
Acute inflammation of renal (kidney) glomeruli
Foodborne Disease

36. Epidemiology of Acute Streptococcal Infection
Predilection for upper respiratory tract or skin
Group A commonly colonize oropharynx of healthy children
M-types of strains colonizing throat differ from those on skin
Rapidly killed after phagocytosis, but cell walls not digested and may lead to chronic inflammatory lesions
Pharyngitis transmitted by droplets from respiratory secretions
Crowding increases risk (e.g., classrooms, day care facilities)
Pyoderma transmitted by direct contact with infectious lesions

37. Nonsuppurative Sequelae of Acute Group A Streptococcal Infection
Acute Rheumatic Fever (ARF)
Inflammatory reaction characterized by arthritis, carditis, chorea (disorder of CNS with involuntary spastic movements), erythema marginatum (skin redness with defined margin), or subcutaneous nodules
Within 2-3 weeks following pharyngitis
Epidemic pharyngitis: ARF in as many as 3%
Sporadic pharyngitis: ARF in 1 per 1000
Morbidity & mortality linked to subsequent disease of heart valve (Rheumatic Heart Disease)
Poorly understood pathogenesis with several proposed theories including cross-reactivity of heart tissues & strep AGNs
?? (Type ?? hypersensitivity, exotoxins, direct invasion) II

38. Nonsuppurative Sequelae of Acute Group A Streptococcal Infection (cont
Acute Glomerulonephritis
Follows either respiratory (pharyngitis) or cutaneous (pyoderma) streptococcal infection
Associated with well-defined group of M-types
Incidence varies from <1% to 10-15%
Most often seen in children manifesting as dark, smoky urine with RBC's, RBC casts, white blood cells, depressed serum complement, decreased glomerular filtration rate
Latent period: 1-2 weeks after skin infection and 2-3 weeks after pharyngitis
Granular accumulations of immunoglobulin due to deposition of immune complexes within the kidney
(Type ?? Hypersensitivity)
III

40. Determinants of Pathogenicity Cellular Virulence Factors
Capsule
Antiphagocytic; Nonspecific adherence
Hyaluronic acid (polysaccharide) mimics animal tissue
Lipoteichoic Acid
Cytotoxic for wide variety of cells
Adherence: Complexes with M protein (LTA-M) and binds to fibronectin on epithelial cells
M-Protein
LTA-M protein is adhesin
Antiphagocytic
Inhibits alternate C’ pathway and opsonization
M-like Proteins: bind IgM and IgG
F Protein: mediates adherence

41. Extracellular Virulence Factors
Exotoxins:
Streptolysin O (SLO):
Hemolytic and Cytolytic
Prototype of oxygen-labile and thiol-activated cytolytic exotoxins (e.g., Streptococcus, Bacillus, Clostridium, Listeria)
Lytic for variety of cells: bind to cholesterol-containing membranes and form arc- or ring- shaped oligomers that make cell leaky (RBC's, WBC’s, PMN's, platelets, etc.)
Causes sub-surface hemolysis on BAP
Stimulate release of lysosomal enzymes
SLO titer indicates recent infection ( in pediatric populations)

42. Extracellellular Virulence Factors (cont.)
Exotoxins (cont.):
Streptolysin S (SLS):
Hemolytic and Cytolytic
Oxygen stable, non-antigenic
Lytic for red and white blood cells and wall-less forms (protoplast, L- forms)
Causes surface hemolysis on BAP
Lysogeny: Lysogenized bacteriophages play key role in directing synthesis of various Group A streptococcal enzymes and toxins
Pyrogenic Exotoxin (erythrogenic toxin)
Phage-associated muralysins (lyse cell walls) produced by both Groups A and C

43. Extracellular Virulence Factors (cont.)
Exotoxins (cont):
Pyrogenic (Erythrogenic) Exotoxins (Types A, B &C)
Produced by more than 90% of Grp A strep
Lysogeny: Structural gene is carried by temperate bacteriophage, as is the case with diphtheria toxin
Mediate pyrogenicity (fever)
Causes scarlet fever (scarletiniform) rash
Increase susceptibility to endotoxic shock
Type C toxin increases permeability of blood-brain barrier
Enhance DTH
Mitogenic for T lymphocytes (cause cell division), myocardial and hepatic necrosis, decrease in antibody synthesis
Immunomodulators (superantigens): stimulate T cells to release cytokines
Cardiohepatic toxin

44. Extracellular Virulence Factors (cont.)
Enzymes:
Nucleases: Four antigenic types (A,B,C,D)
Facilitate liquefication of pus generating growth substrates
Nucleases A, C have DNase activity
Nucleases B, D also have RNase activity
Streptokinases: Two different forms
Lyse blood clots: catalyze conversion of plasminogen to plasmin, leading to digestion of fibrin
C5a Peptidase: destroys C’ chemotactic signals (C5a)
Hyaluronidase: hydrolyzes hyaluronic acid
Others: Proteinase, NADase, ATPase, phosphatase, etc.

45. Lab Identification of S. pyogenes (Group A) Beta-hemolytic
Primary culture by pour or streak plate
Domed,grayish/opalescent colonies
Encapsulated cells produce mucoid colonies
Beta-hemolytic
Zone several times greater than diameter of colony

46. TSA
S. pyogenes

47. S. pyogenes (Group A) (cont.)
Lab Identification of
S. pyogenes (Group A) (cont.)
Catalase Negative: Differentiates from Staphylococcus
Bacitracin test: presumptively distinguishing between Group
A beta-hemolytic streptococci (bacitracin POS) and other beta-hemolytic streptococci that are isolated from pharyngeal swabs (95% sensitivity for Grp A strep)
Rapid Identification Tests:
Based on extraction of Group A carbohydrate directly from throat swabs
ELISA, Coagglutination, Fluorescent Antibody

49. Streptococcus agalactiae
Group B Streptococcus
Streptococcus agalactiae

50. Group B Streptococcal Infections

51. Grp B Streptococcal Infections (cont.)

52. Age-Specific Attack Rates of Group B Streptococcal Disease

53. Epidemiology of Neonatal Group B Streptococcal Disease

54. Group B Streptococcus S. agalactiae
Diagnostic Laboratory Tests
CAMP factor positive
Hippurase positive

55. Enhanced Zone of Hemolysis
CAMP Factor Test
S. aureus
(Spingomyelinase C)
Group B Streptococcus
(CAMP Factor)
Group A Streptococcus
Enhanced Zone of Hemolysis

56. Hippurase NEG

57. Grp B Streptococci
and
Campylobacter
Hippurase POS

59. Streptococcus pneumoniae
Commonly referred to as pneumococcus
Formerly Diplococcus pneumoniae

60. Streptococcus pneumoniae Infections

61. Pneumococcal Infections (cont.)
Epidemiology (cont.)

62. S. pneumoniae
Diplococcus

63. S. pneumoniae: lancet-shaped diplococcus

64. S. pneumoniae Virulence Factors

65. S. pneumoniae Seasonal Incidence

66. Comparison of Morbidity & Mortality for Bacterial Meningitis

67. Genetic Variation (Mutation)

68. Beginning of Molecular Genetics

69. Transformation (In vivo) (Griffith)

70. Streptococcus pneumoniae
Diagnostic Laboratory Tests
Optochin sensitivity (Taxo P disc)

71. Streptococcus pneumoniae
Optochin Sensitivity
Taxo P
Streptococcus pneumoniae

73. Enterococcus faecalis Enterococcus faecium
GI tract of humans and animals
Group D carbohydrate cell wall antigen
Formerly Streptococcus

74. Enterococcal Infections

75. Enterococcal Infections (cont.)

76. Important nosocomial pathogen
Vancomycin resistant Enterococcus (VRE)

77. Enterococcus Diagnostic Laboratory Tests Resistant to bile
Esculin hydrolysis
BEA media

78. Enterococcus
Group D Streptococcus
Bile Esculin Agar
POS
Bile Esculin Agar
NEG

79. Esculin Bile Assay

81. REVIEW

82. Lancefield Serogroup Classification of Beta-Hemolytic Streptococci Important in Human Disease
Group A Streptococci:
Streptococcus pyogenes
One of Most Important Human Pathogens
Suppurative Diseases: Pharyngitis; Scarlet Fever;
Cutaneous & Soft Tissue Infections; Systemic Disease
Non-Suppurative Sequelae:ARF,RHD,AG
Group B Streptococci:
Streptococcus agalactiae
Systemic, Cutaneous, UTI's
Neonatal disease
Obstetric Complications
REVIEW

83. Nonsuppurative Sequelae of Acute Group A Streptococcal Infection
Acute Rheumatic Fever (ARF)
Inflammatory reaction characterized by arthritis, carditis, chorea (disorder of CNS with involuntary spastic movements), erythema marginatum (skin redness with defined margin), or subcutaneous nodules
Within 2-3 weeks following pharyngitis
Epidemic pharyngitis: ARF in as many as 3%
Sporadic pharyngitis: ARF in 1 per 1000
Morbidity & mortality linked to subsequent disease of heart valve (Rheumatic Heart Disease)
Poorly understood pathogenesis with several proposed theories including cross-reactivity of heart tissues & strep AGNs
?? (Type ?? hypersensitivity, exotoxins, direct invasion) II
REVIEW

84. Nonsuppurative Sequelae of Acute Group A Streptococcal Infection (cont
Acute Glomerulonephritis
Follows either respiratory (pharyngitis) or cutaneous (pyoderma) streptococcal infection
Associated with well-defined group of M-types
Incidence varies from <1% to 10-15%
Most often seen in children manifesting as dark, smoky urine with RBC's, RBC casts, white blood cells, depressed serum complement, decreased glomerular filtration rate
Latent period: 1-2 weeks after skin infection and 2-3 weeks after pharyngitis
Granular accumulations of immunoglobulin due to deposition of immune complexes within the kidney
(Type ?? Hypersensitivity)
III
REVIEW

85. Determinants of Pathogenicity Cellular Virulence Factors
Capsule
Antiphagocytic; Nonspecific adherence
Hyaluronic acid (polysaccharide) mimics animal tissue
Lipoteichoic Acid
Cytotoxic for wide variety of cells
Adherence: Complexes with M protein (LTA-M) and binds to fibronectin on epithelial cells
M-Protein
LTA-M protein is adhesin
Antiphagocytic
Inhibits alternate C’ pathway and opsonization
M-like Proteins: bind IgM and IgG
F Protein: mediates adherence
REVIEW

86. Extracellular Virulence Factors
Exotoxins:
Streptolysin O (SLO):
Hemolytic and Cytolytic
Prototype of oxygen-labile and thiol-activated cytolytic exotoxins (e.g., Streptococcus, Bacillus, Clostridium, Listeria)
Lytic for variety of cells: bind to cholesterol-containing membranes and form arc- or ring- shaped oligomers that make cell leaky (RBC's, WBC’s, PMN's, platelets, etc.)
Causes sub-surface hemolysis on BAP
Stimulate release of lysosomal enzymes
SLO titer indicates recent infection ( in pediatric populations)
REVIEW

87. Extracellellular Virulence Factors (cont.)
Exotoxins (cont.):
Streptolysin S (SLS):
Hemolytic and Cytolytic
Oxygen stable, non-antigenic
Lytic for red and white blood cells and wall-less forms (protoplast, L- forms)
Causes surface hemolysis on BAP
REVIEW

88. Extracellular Virulence Factors (cont.)
Exotoxins (cont):
Pyrogenic (Erythrogenic) Exotoxins (Types A, B &C)
Produced by more than 90% of Grp A strep
Lysogeny: Structural gene is carried by temperate bacteriophage, as is the case with diphtheria toxin
Mediate pyrogenicity (fever)
Causes scarlet fever (scarletiniform) rash
Increase susceptibility to endotoxic shock
Type C toxin increases permeability of blood-brain barrier
Enhance DTH
Mitogenic for T lymphocytes (cause cell division), myocardial and hepatic necrosis, decrease in antibody synthesis
Immunomodulators (superantigens): stimulate T cells to release cytokines
Cardiohepatic toxin
REVIEW

89. Extracellular Virulence Factors (cont.)
Enzymes:
Nucleases: Four antigenic types (A,B,C,D)
Facilitate liquefication of pus generating growth substrates
Nucleases A, C have DNase activity
Nucleases B, D also have RNase activity
Streptokinases: Two different forms
Lyse blood clots: catalyze conversion of plasminogen to plasmin, leading to digestion of fibrin
C5a Peptidase: destroys C’ chemotactic signals (C5a)
Hyaluronidase: hydrolyzes hyaluronic acid
Others: Proteinase, NADase, ATPase, phosphatase, etc.
REVIEW

90. Epidemiology of Neonatal Group B Streptococcal Disease
REVIEW

91. REVIEW

92. Streptococcus pneumoniae Infections
Infections from endogenous spread from naso- or orapharynx
Pneumonia; sinusitis; otitis media; bacteremia; meningitis
Colonization highest in children
Antecedent viral respiratory tract disease increases risk
Most common in cold months
Polyvalent vaccine available (newly available for children)
REVIEW

93. S.pneumoniae Virulence Factors
REVIEW

94. Comparison of Morbidity & Mortality for Bacterial Meningitis
REVIEW

95. Genetic Variation (Mutation)
REVIEW

96. Beginning of Molecular Genetics
REVIEW

97. Transformation (In vivo) (Griffith)
REVIEW

98. Enterococcal Infections
Group D cell wall antigen
Enterococcus faecalis; Enterococcus faecium
GI tract of humans and animals
UTI most common; wound infections; bacteremia; endocarditis
Most infections from endogenous source
Prolonged hospitalization and broad-spectrum antibiotics increase risk
Antibiotic resistance (VRE)
REVIEW