The document discusses the genus Streptococcus, including its classification, morphology, growth characteristics, biochemical reactions, and clinical significance. It describes various species, such as Streptococcus pyogenes and Streptococcus pneumoniae, detailing their pathogenicity, diseases caused, laboratory diagnosis, and treatment options. The document also covers epidemiology, resistance patterns, and specific infections associated with different streptococci groups.

1. STREPTOCOCCUS
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2. Strepto-cocci
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3.  Commensals or Parasites of man & animals
 or
 Saprophytes of decaying matter
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4. Genus Streptococcus
Gram-Positive Cocci in Pairs or Chains
v/s
Staph – gram positive cocci in clusters (grape like)
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5. Gram-Positive
Streptococcus
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6.  Gram positive cocci in clusters
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7. Classification
 On the basis of their growth characteristics on
blood agar
 Alpha hemolytic
 Beta hemolytic
 Gamma hemolytic
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8. Example –
Streptococcus viridans (Viridans = green)
Streptococcus pneumoniae
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9. 9

10. Example – enterococcus group
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11. 11

12. 12

13. Beta hemolytic streptococci
Lancefield grouping
 Group A to Group V without I and J
 Divided according to differences in Cell wall
carbohydrate antigen
 Out of all these, those of Group A known as
streptococcus pyogenes produce majority of
human infections
 Group B are known as S agalactiae
13

14. Group A beta hemolytic streptococci /
strep pyogenes
 These are further subdivided according to sell
surface M, T and R antigens
 Griffith typing
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15. 15

16. Streptococcus Pyogenes
(Group A beta hemolytic)
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17. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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18. Morphology
 Cocci in long chains
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19. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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20. Growth characteristics
 Facultative anaerobe, grows best in presence
of 10% CO2
 Grows on enriched media only
 Beta hemolysis around colonies on blood
agar
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21. 21

22. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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23. Biochemical reactions
 Ferment sugars – produce acid , no gas
 Catalase negative
 Catalase helps to differentiate staphylococci
from streptococci
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24. Catalase test
 Add hydrogen peroxide to culture material
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25. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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26. Resistance
 Most are still susceptible to penicillin and
erythromycin
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27. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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28. Pathogenicity and virulence
 Antigenic structure
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Antigens on surface of strep cross react with body proteins
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Capsular hyaluronic acid – human joints – autoimmune arthritis
Carbohydrate antigen – cardiac valves – rheumatic heart
disease
 Toxins
 Enzymes
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Streptolysin O – ASO titre for diagnosis
Streptolysin S – for hemolysis around colonies
Streptokinase – lysis of clots – given iv for treatment of MI
DNA ase – Anti DNAase is useful for diagnosis of S.
pyogenes skin infection
Hyaluronidase – breaks down tissues – helps in spread of
strep infection
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29. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
29

30. Epidemiology
 Source – human upper respiratory tract –
throat, pharynx, nose
 Transmission – direct contact, fomites
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31. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
31

32. Diseases caused
 Pus producing (suppurative)
Respiratory infections
 Skin and soft tissue infections
 Genital infections
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 Non suppurative
Acute rheumatic fever
 Rheumatic heart disease
 Acute glomerulonephritis (kidney)
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33. Respiratory infections
 Tonsillitis
 Pharyngitis
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34.  tonsillitis
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35.  pharyngitis
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36. Skin and soft tissue infections
 Skin
Erysipelas – involves lymphatics – older pts
 Impetigo – young children
 Pyoderma
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 Soft tissue
Cellulitis
 Necrotising fascitis
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37. Erysipelas
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38. Impetigo
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39. Pyoderma
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40. Cellulitis
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41. Necrotising fascitis
flesh eating bacteria (anaerobes)
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42. Non suppurative complications
After 1-3 weeks of primary infection
Due to cross reactivity
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43. Acute rheumatic fever
 Follows streptococcal sore throat
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44. Acute glomerulonephritis
 Cross reaction between streptococci and
kidney tissues
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45. Rheumatic heart disease
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46. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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47. Suppurative infections
 Examination of pus/throat swabs
 Microscopy, staining and culture
 Gram stain
 Blood agar
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48. Non suppurative infections
 Demonstration of antibodies
 Like ASO and anti DNA ase B
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49. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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50. Treatment
 Penicillin
 Erythromycin
 Drugs have no effect if non suppurative
complications have developed
 Prophylaxis – can prevent rheumatic fever,
not glomerulonephritis
50

51. OTHER STREPTOCOCCI
BETA HEMOLYTIC - GROUP B
AND GROUP D
ALPHA HEMOLYTIC (VIRIDANS
GROUP)– STREPTOCOCCUS
PNEUMONIAE
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52. Group B Streptococcus
Streptococcus agalactiae
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53. Group B Streptococcus
S. agalactiae
1. Infect newborns
2. Infection acquired through maternal vagina during
birth
3. Presents as meningitis, pneumonia or septicemia
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54. Diagnostic Laboratory Tests
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CAMP factor positive
Hippurase positive
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55. CAMP (Christie, atkins, munchpeterson) Factor Test aureus
S.
Group B
Streptococcus
(Spingomyelinase C)
(CAMP Factor)
Group A
Streptococcus
Enhanced
Zone of
Hemolysis
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56. Hippurase NEG
Streptococcus agalactiae not added
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57. Grp B Streptococci
Hippurase POS
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58. Viridans group
Streptococcus pneumoniae
• Commonly referred to as pneumococcus
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59. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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60.  Lancet shaped (one end broad, other
pointed)
 Capsulated
 Diplococci
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61. S. pneumoniae: lancet-shaped diplococcus
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62. S. pneumoniae
• Diplococcus
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63. Capsular stain
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64. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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65. Growth characteristics
 Alpha hemolysis on blood agar
 On further incubation, the colonies become
flat with raised edges and central elevation
resembling carrom coins
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66. Example –
Streptococcus viridans (Viridans = green)
Streptococcus pneumoniae
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67. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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68. Biochemical reactions
 Hiss serum water – fermentation of inulin
 Bile solubility
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69. Inulin fermentation
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70. 70

71. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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72. Resistance
 Pneumococcus is sensitive to optochin –
used for typing
 Resistance to penicillin – third generation
cephalosporin like ceftriaxone
 May be resistant to third gen ceph also
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73. 73

74. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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75. Pathogenicity and virulence
 Capsule
 Toxins – pneumolysin
 C reactive protein
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76. Capsule
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77. Pneumolysin
 Membrane damaging toxin
 Cytotoxic activity
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78. C reactive protein
 Abnormal immunoglobulin against C protein
of S. pneumoniae appears in serum of
patients
 Also seen in acute phase of infections and
inflammations
 CRP titre is tested in acute infections
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79. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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80. Epidemiology
 Source – respiratory tract of humans
 Spread – droplets
 Carriers – pharynx
 Low immunity is responsible for fulminant
infections
RSV infection, pulmonary congestion, stress,
malnutrition, alcoholism
 Splenectomy
 Sickle cell disease
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81. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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82. Diseases caused
 Middle ear – otitis media
 Para nasal sinuses – sinusitis
 Respiratory tract – pneumonia, bronchitis,
empyema
 Meningitis is secondary to otitis media,
penumonia, sinusitis and conjunctivitis
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83. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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84. Laboratory diagnosis
 Sample
sputum – pneumonia
 septicemia - blood culture
 Otitis media - fluid from middle ear
 Meningitis - CSF
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 Method
Gram stain, microscopy
 culture
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85.  Latex agglutination for pneumococcal antigen
in serum of patients
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86. Description headings
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Morphology
Growth characteristics
Biochemical reactions
Resistance
Pathogenicity and virulence
Epidemiology
Diseases caused
Laboratory diagnosis
Treatment
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87. Treatment
 Penicillin
 Amoxycillin
 ceftriaxone/ceftazidime
 Vancomycin
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88. Prophylaxis
 Pneumococcal conjugate vaccine is available
 Given to splenectomy patients, sickle cell
anemia patients and susceptible individuals
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89. GROUP D STREPTOCOCCI
Enterococcus faecalis
Enterococcus faecium
• GI tract of humans and animals
• Group D carbohydrate cell wall antigen
• Formerly Streptococcus
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90.  Cause UTI, wound infection
 Endocarditis
 Intra abdominal abcesses
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91. 91