1. STREPTOCOCCUS CLASSIFICATION : By two ways: 1-Haemolytic Activity Classification: a)Beta-haemolytic streptococci: complete haemolysis, decolorization of Hb, haemolysis more marked on anaerobiasis. b) Alpha-haemolytic streptococci: partial haemolysis, a green brown colour due to reduction of Hb. c) Non-haemolytic streptococci: no alpha or beta-haemolysis, Hb slightly discolourized.

2. 2- Lancefield Classification: @ Beta haemolytic streptococci produce group specific Ags. C-carbohydrates. @ Identified by group specific antiserum (Lancefield groping is A-H & K-V) @ Most important beta-haemolytic S. pyogenes gp. A. @ Other pathogenic streptococci belong to groups B, C, D, F, G.

3. STREPTOCOCCI SPECIES & GROUPS: Main species and groups are: 1. S. pyogenes (Lancefield gp. A). 2. S. agalactiae (Lancefield gp. B). 3. E. faecalis (Lancefield gp. D)

4. Other streptococci include: 4. S. viridans e.g.: S. mitis, S. mutans, S. sanguis 5. Anaerobic streptococci. 6. S. pneumoniae.

5. NORMAL HABITAT: @ Found in water, dust, milk, vegetation, milk products. @ Commensal in URT: S. pyogenes (groups C, & G), & viridans strep. @ Commensal in GIT: E. faecalis @ Commensal female genitalia : Group B streptococci

6. PATHOGENICITY: 1- S. pyogenes (group A): a) Tonsillitis & pharyngitis. b) Peritonsilar abscess (quinsy). c) Scarlet fever, caused by erythrogenic toxin in 2% of S. pyogenes strains.

7. d) Otitis media and mastoiditis. e) Puerperal sepsis. f) Skin infections, e.g.: cellulitis, erysipelas of face & scalp- حمرة impetigo (blistering of skin). g) Septicaemia, & endocarditis.

8. 2- Post-streptococcal diseases: Complications of acute group (A) streptococcal infection following an immunological response: a)Acute glomerulonephritis, follows strep. skin infection. b) Rheumatic fever, follows a respiratory strep. infection, damaging of heart valves & muscles.

9. 3- Enzymes of S. pyogenes: a) Streptokinase: lyses fibrin. b) Hyaluronidase, breaks down hyaluronic acid & makes S. pyogenes spread in tissues. c) DNAses (A, B, C, D), break DNA. d) DPNase, kills Leucocytes by attacking diphospho-pyridine nucleotide (DPN) in cell.

10. Toxins of S. pyogenes : a)Streptolysin (O) : lyses RBC & stimulates production of ASO. b) Streptolysin (S) : lyses RBC to give beta- haemolysis on B.A. c) Erythrogenic toxin : causes skin rash of scarlet fever.

11. 4-S.agalactiae (group B) Causes the following: a)Neonatal septicaemia, pneumonia, meningitis. b) Septic abortion, puerperal sepsis, vaginitis.

12. 5- E. faecalis (group D) Causes: a) UTI, in association with E. coli. b) Ulcers, wound infections c) Endocarditis, meningitis.

13. 6- S. viridans : Causes the following: a) Infective endocarditis, (in patients with damaged heart valves). b) Dental caries. c) Abdominal abscess, Brain abscess.

14. 7-S. pyogenes (groups C,G) Causes the following: a)Sinusitis bacteraemia. b) Endocarditis urogenital infections. c) Wound infections.

15. LABORATORY DIAGNOSIS SPECIEMENS: 1- Throat swabs, pus, blood (culture & ASO) 2- For S. agalactiae : HVS, blood, CSF, ear swabs (infants) 3- For E. faecalis: urine and pus 4- For streptococcal endocarditis: blood, urine

16. MICROSCOPY: @ Streptococci : gram positive, non-motile, some strains are capsulated. @ Morphology differs: a) In fluid media: Long chains. b) In pus & solid media: Short chains, in pairs or single.

17. CULTURE: @ Grow aerobically & anaerobicaly. Temp. 15 - 45˚C. @ Colonies on B.A. less than 1 mm. Colourless or grey - white dry, shiny, irregular outline. @ Pathogenic streptococci produce haemolysis on B.A.

18. 1- S. pyogenes (group A): @ Shows beta-haemolysis on B.A. @ Sensitive to bacitracin @ Other strep. species are also sensitive. @ Hence confirm by Lancefield grouping @ Crystal violet B.A. selective for S. pyogenes & inhibits S. aureus. @ Best medium to isolate S.pyogenes from throat & skin. @ S. pyogenes will not grow on MacConkey

19. 2- S. agalactiae (group B) @ ß-hemolytic on B.A. @ Kanamycin B.A. is selective to isolate from urogenital sites @ On serum starch agar, It produces an orange pigment. @ Some strains grow on Mc Conkey agar.

20. CAMP Test: @ S. agalactiae produces the protein CAMP (Christie, Atkins, & Munch Peterson) factor. @ This factor interacts with staph. beta-haemolysin on RBC.

21. CAMP is performed as follows: a) Streak Staph. across B.A plate, inoculate test organism at right angle without touching the staph. b) Inoculate E. faecalis across plate as a negative control. c) Incubate plate at 37˚C overnight, look for interaction of test organism with staph. Positive: identifies S. agalactiae.

22. CAMP Toxin method: @ Add 2 drops of Staph. (B) toxin to a B.A. plate culture of S. agalactiae. @ After 2 hrs incubation, development of haemolytic area around colonies indicates presence of S. agalactiae.

23. Test organism Staph. Inoculum Arrow-head of haemolysis produced by S.agalactiae E. Faecalis Negative control

24. 3- Beta-haemolytic group (C) & group (G) streptococci. @ Isolated from throat swabs and blood. @ Identification is made by Lancefield grouping.

25. 4- S. viridans : @ Show α-haemolysis, @ Optochin resistant @ Not soluble in bile

26. 5- E. faecalis (group D) : @ Beta-haemolytic, alpha- haemolytic, or non-haemolytic. @ Identified by positive rapid litmus milk reduction test. @ On Mc Conkey, give small, dark red colonies.

27. Lancefield grouping 1- Earlier, grouping was done by a precipitation test applying heat & HCl to extract antigen of cell wall. 2- Test is latex, made by adding organism to antiserum containing latex particles on a slide. @ Follow manufacturer procedure

28. BILE SOLUBILITY TEST: @ S.pneumoniae (soluble)-S. viridans (insoluble). 1- Emulsify colonies of test organism in a tube with 2 ml. distilled water. 2- Divide the suspension into two tubes. 3- To tube 1 add 2 drops sod. Deoxycholate, mix. 4- To tube 2 add 2 drops distilled water, mix. 5- Leave tubes for 15 min., look for clearing of turbidity in tube 1. Result: Clearing : soluble (Pneumococcus) No clearing: insoluble (S. viridans).

29. LITUMS MILK DECOLORIZATION TEST: @ E.faecalis decolorizes litmus milk. 1- Inoculate heavily test organism in 0.5 ml. litmus milk medium. 2- Incubate at 37˚C for 4 hrs., examine every ½ hr for reduction (litmus changes from purple to white or pale yellow). 3- Incubation not more than 4 hrs, since S. viridans reduces litmus after 4 hrs. Result: Positive means E. faecalis.

30. ASO TITRE @ To investigate post-streptococcal complications following Strep. infection Other conditions giving rise in titre are: Pneumococcal pneumonia, tuberculosis, gonorrhea, hepatitis, and rheumatoid arthritis, group (C) & group (G) strep. infections @ ASO is estimated by : 1- Latex slide agglutination. 2- Microtitration or tube haemolysis test.

31. DNAse ANTIBODY TEST: @ To diagnose acute glomerulonephritis. @ Use commercial kits.

32. STREPTOZYME TEST: @ Available commercially. @ A slide haemagglutination test to detect: * ASO, * Anti-DNAse B, * Anti-hyaluronidase, * Anti-NADase, * Anti-streptokinase.

33. ANTIMICROBIAL SENSITIVITY : @ S.pyogenes & S. agalactiae: sensitive to: * penicillin * erythromycin. @ S.pyogenes is resistant to: *polymyxin, *nalidixic acid, *sulphonamides.

34. S.PNEUMONIAE SPECIES: Only S.pneumoniae (pneumococcus) NORMAL HABITAT: Commensal of URT.

35. PATHOGENICITY: 1- Lobar pneumonia, bronchitis. bronchopneumonia, 2- Bacteraemia, meningitis. 3- Endocarditis, pericarditis. 4- Otitis media, sinusitis, conjunctivitis.

36. ENZYMES: Hyaluronidase. TOXINS: Leucocidin, haemolysin.

37. LABORATORY DIAGNOSIS SPECIMENS: 1- Sputum: microscopy, culture. 2- Blood for culture. 3- CSF: microscopy, culture, biochemistry.

38. MICROSCOPY: S.pneumoniae: @Gram positive, non-motile, diplococcus, capsulated. @ Identified serologically (quelling reaction) using polyvalent antiserum.

39. CULTURE: @ Cultivated on chocolate agar (10% CO 2 ) @ Colonies flat with raised edges, giving a ring shape (draughtsman). @ α-haemolytic, & sensitive to optochin.

40. BIOCHEMICAL REACTIONS @ Bile solubility positive. ANTIMICROBIAL SENSITIVITY @ Sensitive to: Penicillin, erythromycin, co-trimoxazole.

41. ANAEROBIC COCCI SPECIES: * Peptococcus * Peptostreptococcus. HABITAT: skin, mouth, vagina, gastro-intestinal tract.

42. PATHOGENICITY: 1- Septicaemia, puerperal sepsis. 2- Bone and joint infections. 3- Abscesses, deep infected wounds, and ulcers.

43. MICROSCOPY: @ Gram positive: in chains: (Peptostreptococcus) in groups: (Peptococcus) @ Catalase negative.

44. CULTURE: @ Cultivated in: Thioglycollate broth. @ On B.A. colonies are small, shiny, non-haemolytic.

45. ANTIMICROBIAL SENSITIVITY @ Sensitive to: Penicillin, metronidazole, @ Peptococci are resistant to novobiocin, @ Peptostreptococci are sensitive to novobiocin.

46. Esculin hydrolysis CAMP Litmus milk Optochin Bile BacitracinCatalaseSpecies ----+-S.pyogenes (group A) -+----S.agalactiae (group B) (group B) +-+--- E.faecalis (group D) ------S.viridans ---+--S.pneumoniae FEATURES OF STREPTOCOCCI