1. Dr. Tamer Bedair Lecturer of Medical Microbiology and Immunology

2. Contents: 1. Character of Streptococci 2. Classification of Streptococci 3. Strept. pyogenes a. virulence factors and pathogenesis b.diseases c. lab. Daignosis d. post Streptococcal sequelae or complication e. treatment and prevention 4. Strept. pneumoniae (pneumococci) 5. Viridans Strept. 6. Strept. agalactia 5. Strept. faecalis (enterococci)

3. Causes of tonsilitis or pharyngitis Group A hemolytic strept. is the most common cause especially in children Viral causes (most common in adults) as rhinoviruses, influenza virus, parainfluenza, adenovirus, EBV, HSV…

4. Characters of Streptococci Morphology: Gram positive cocci Chains or pairs Pathogenis strains usually capsulated Non motile and Non spore forming Culture character: Fastidious and grow on blood agar except strept faecalis which is not fastidious and can grow on nutrient agar All Strept. need 0.03% CO2 except Strept. pneumoniae which need CO2 5—10% Biocemical reaction: All Streptococci are Catalase negative (Staphylococci are catalase positive)

5. Classification Oxygen requirements Anaerobic (Peptostreptococcus) Aerobic or facultative anaerobic (Streptococcus) Serology (Lanciefield Classification) Hemolysis on Blood Agar (BA)

6. I-Classification of Streptococci Based on Hemolysis on Blood Agar Streptococci  -hemolysis  -hemolysis  -hemolysis Hemolysis on BA –  -hemolysis Partial hemolysis Green discoloration around the colonies e.g. non-groupable streptococci (S. pneumoniae & S. viridans) –  -hemolysis Complete hemolysis Clear zone of hemolysis around the colonies e.g. Group A & B (S. pyogenes & S. agalactiae) –  -hemolysis No lysis e.g. Group D (Enterococcus spp)

7. Hemolysis on Blood agar  -hemolysis  -hemolysis  -hemolysis

8. II-Serology: Lanciefield Classification Streptococci Group A S. pyogenes Group B S. agalactiae Group C S. equisimitis Group D Enterococcus Other groups (E-U) Lanciefield classification Streptococci classified into many groups from A to U Classification based on C- carbohydrate antigen of cell wall Groupable streptococci A, B and D (more frequent) C, G and F (Less frequent) Non-groupable streptococci S. pneumoniae (pneumonia) viridans streptococci e.g. S. mutans

9. Group A streptococci = Strept.pyogenes Group A streptococcal infections affect all ages but peak incidence at 5-15 years of age The most common infection caused by Strept. pyoenes is pharyngitis and tonsillitis especially in children

10. Pathogenesis and Virulence Factors Structural components M protein, which interferes with opsonization and phagocytosis Hyaluronic acid capsule, which interferes with and phagocytosis Enzymes Streptokinases Deoxynucleases C5a peptidase Eythrogenic toxins Produced by lysogenic (temperate) phage and causes rash of scarlet fever & associated with a toxic shock-like syndrome Streptolysins Streptolysin O lyse red blood cells, white blood cells, and platelets Streptolysin S facilitate the spread of streptococci through tissues through tissues

11. Diseases caused by Strept. pyogenes A)Supppurative infections B) Toxogenic diseases C) Post streptococcal sequelae

12. Suppurative (pus forming) Pharyngitis & acute follicular tonsilitis Otitis media Bronchopneumonia Bacteremia and septicemia Meningitis Skin infection, Impetigo, Pyoderma, erysipelas and cellulitis

13. Cellulitis Impetigo

14. B) Toxogenic dise 1- toxic shock like syndrome - similar in pathogenesis and manifestation to staphylococcal toxic shock syndrome. 2-Scarlet fever (erythrogenic toxin) Usually affects children,characterized by fever, skin rash & stomatitis (Strawberry tongue). The skin rash is due to direct effect of the erythrogenic toxin on the skin.

15. Lab. diagnosis 1. sample: according to clinical disease - tonsilitis, pharyngitis and scarlet fever: throat swab - erysipelas, and bacteremia: blood (blood culture) 2. Direct microscopic examination by Gram stain: G. +ve cocci, capsulated in long chain 3. culture: on BA, at 37 C → β hemolytic colonies 4. Colonies identification: a. film stained by G. stain: b. biochemical reactions: catalase -ve & bacitracin sensitive

17. Diagnosis of scarlet fever By throat swab: processed as before…… + 5-Schultz Charlton reaction (rapid diagnosis ): -Toxin anti toxin neutralization test -Injection of antierythrogenic toxin in the rash → disappearance of the rash within 6-12 hours, due to neutralization of the toxin with specific antitoxin. 6. Dick test : - Toxin anti toxin neutralization test - Used to assess susceptibility of individual and detect immunity to scarlet fever

18. C) Post streptococcal sequelae Non suppurative complication which follow strept. pyogenes infection by 1-3 weeks Affect mainly in children between 5 – 15 years Occur following pharyngitis or skin infection (nephrogenic strains) No bacteria present in pharynx at time of occurance of the complications These complication includes 1. rheumatic pancarditis (rheumatic fever) with subsequent damage in heart valves 2. glomerulonephritis 3. migratory polyarthritis

19. C) Post streptococcal sequelae Pathogenesis: 1. similarity and cross reactivity (molecular mimicry): M protein of Strept pyogenes is similar with heart myosin glycoprtein so antibodies against M protein will cross react with heart myosin glycoprtein (autoimmunity) 2. Immune comples disease (type III hypersensitivity): Due to prolonged antigenemia in vivo, antigen antibody complexes will be formed into the circulation and precipitate on basement membrane of renal glomeruli ten damage of renal glomeruli occur by type III hypersensitivity

20. C) Post streptococcal sequelae Diagnosis: Jones criteria………. Lab. Diagnosis: a-Non specific tests: C- reactive protein High ESR b-Specific tests : by detection of an increase in antibody titer to at least one of the streptococcal antigens including antistreptolysin O (ASO) which is most widely used,anti-DNase, antihyaluronidase& antistreptok

21. ASO aim: to determine the titre of Ab against Sterptolysin O type: done in tube or on slide (passive agglutination) interpretation: titre = highest dilution of serum with no haemolysis titre expressed in Todd’s unit significant titre = 200 or more Todd’s unit

22. Treatment and prevention: No vaccine is available to combat S. pyogens infections. The antibiotic of choice is penicillin (inhibit cell wall peptidoglycan synthesis) or erythromycin (inhibit 50S of ribosome) Long acting penicillin can be used to prevent recurrent pharyngitis and its immune-mediated sequelae.

23. Group B Streptococci (Stretococcus agalactiae) Flora of vagina Morpholog and culture character : similar with Strept. pyogenes Biochemical reaction: catalase -ve & bacitracin resistant& CAMP test +ve Diseases: Neonatal septicemia, pneumonia and meningitis Prevention: IV ampicillin to pregnant mothers who have Group B in vagina. Diagnosis:……….

24. Strept. pneumoniae Morphology: G. +ve cocci, capsulated, in pairs, non motile and non spore forming. Culture character: grow on blood agar with CO2 5— 10% (capnophilic) →αH Biochemical reactions : catalase –ve, optochain sensitive, bile soluble, ferment inuline Virulence factors: - main virulence is due to polysaccharide capsule → antiphagocytic

25. Strept. pneumoniae - According to polysaccharide capsule → 80 serotypes - Humans infected by pathogenic 23 strains - Quelling reaction: when specific Ab against capsule bind with capsule → capsular swelling Diseases: 1. lobar pneumonia 2. Otitis media 3. Bacteremia and septicemia 4 Septic meningitis

26. Strept. pneumoniae Lab. Diagnosis: sample: sputum, blood 2. Direct microscopic examination by Gram stain: G. +ve cocci, capsulated in pairs (dipolococci) 3. culture: on BA, at 37 C → α hemolytic colonies 4. Colonies identification: a. film stained by G. stain: b. biochemical reactions: catalase -ve & optocain sensitive &………. 5. Quelling reaction:………….

27. Strept. pneumoniae Treatment: penicillin or β lactam antibiotic but if resistance suspected vancomycin can be used Prevention: Polyvalent polysaccharide capsule Ag from most pathogenic 23 strains which infect human → given to to children & elderly & post-spleenectomy

28. Viridans Strept. Bacteria flora of oral cavity Morphology, culture characters: similar to pneumococci but not capsulated Bioch. Reactions: catalase –ve, optochain resistant, bile insoluble, ferment rafinose Diseases: dental plaques, dental caries and infective endocarditis (on tooth extraction in patients with heart diseas). Prevention: any patients with tooth extraction should take prophylactic antibiotics before and after tooth extraction.

29. Group D Streptococci Divided into Enterococci (present in the intestine as flora) Non enterococci not present in the intestine

30. Enterococcus faecalis Flora of intestine → inducator for faecal pollution of water Morphology: G+ve cocci in short chain, non capsulated, non motile, and non spore forming Culture character: the only strept. which can grow on nutrient agar & also grow on blood gar ( ɣ H ) Biochemical reaction: catalase –ve & can grow in 6.5% Na Cl broth Diseases: UTI & intra abdominal sepsis & wound infections Diagnosis: ……… Resist antibiotics and cause nosocomial infections

31. Outline of differentiation between Gram-Positive cocci e.g. S. epidermidis

32. Causes of Membrane on the tonsil Acute follicular tonsilitis: Strept. pyogenes……….. Diphtheria: G +ve bacilli, in chinese letter appearance& cultivated on loffler’s serum or blood agar Oral thrush: Candida which appear as G +ve yeast & cultivated on Sabouraud’s dextrose agar Vincent’s angina: B. vencenti (coiled bacteria) & Fusbacterium (anaerobic fusiform G –ve bacilli) Infectious mononucleosis: EBV which diagnosed by monospot test or Paul Bunnel test

33. Thanks for your attention