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

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)

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

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

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.

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.

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.

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.

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.

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

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

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

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

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

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

Grow aerobically & anaerobicaly. Temp Colonies on B.A. less than 1 mm. Colourless or grey - white dry, shiny, irregular Pathogenic streptococci produce haemolysis on B.A.

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

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

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

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.

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

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

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

4- S. viridans Show Optochin Not soluble in bile

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

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 Follow manufacturer procedure

BILE SOLUBILITY 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).

LITUMS MILK DECOLORIZATION 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.

ASO 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. ASO is estimated by : 1- Latex slide agglutination. 2- Microtitration or tube haemolysis test.

DNAse ANTIBODY To diagnose acute Use commercial kits.

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

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

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

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

ENZYMES: Hyaluronidase. TOXINS: Leucocidin, haemolysin.

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

MICROSCOPY: positive, non-motile, diplococcus, Identified serologically (quelling reaction) using polyvalent antiserum.

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

BIOCHEMICAL Bile solubility positive. ANTIMICROBIAL Sensitive to: Penicillin, erythromycin, co-trimoxazole.

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

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

Gram positive: in chains: (Peptostreptococcus) in groups: Catalase negative.

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

ANTIMICROBIAL Sensitive to: Penicillin, Peptococci are resistant to Peptostreptococci are sensitive to novobiocin.

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