Streptococcus pyogens

General classification scheme on Streptococcus and main focus on S. pyogens

1. Streptococcus Presented by PRASHANT DAHAL BSc. Microbiology Final Year Sunsari Technical College, Dharan

2. Table of Content Table of Contents 1. Introduction 2. Morphology 3. Classification scheme (Lance field classification) 4. Strep. pyogenes 4. Structure and Cultural characters 5. Biochemistry 6. Clinical significances a. Virulence factors b. Pathogenesis c. Disease causing 7. Diagnosis 8. Treatment 9. Other Clinically important Streptococci

3. INTRODUCTION Streptococcus is a genus of Gram positive, anaerobic or facultative aerobic cocci of family Streptococcaceae , within the order  Lactobacillales arranged as a chain or pair in a twisted manner, hence got the name ( Greek : streptos = pliant or chain; coccos = a grain or berry) First isolated and coined by Viennese surgeon  Albert Theodor Billroth in 1877 non-motile (except group-D), non- sporing , capsulated Strong fermenter of carbohydrate releasing Lactic Acid but no gas More than 70 species

4. Morphology Gram-positive cocci ; 0.6–1.0 m in diameter arranged in long chains Some strains of S. pyogens and group C are capsulated by hyaluronic acid capsule Hence, may be mucoid in culture  

5. Classification Scheme Broadly, Streptococci are classified by 3 systems ; Brown’s classification (on basis of hemolysis) Lancefield grouping Pathogenic potential and character

6. BROWN’S CLASSIFICATION Classification is on the basis of type of hemolysis in the blood agar viridans Non- viridans

7. Lancefield Grouping Most widely used scheme in clinical diagnosis Serological classification based on major cell-wall carbohydrate Introduced by American Microbiologist   Rebecca Lancefield in 1970 Mostly used to classify Beta-hemolytic streptococci , but exclude Alpha-hemolytic as NON- GROUPABLE twenty (20) groups A-U without I and J

8. Pathogenic potential and character Grouped into 5 groups: The pyogenic (pus generating) group includes most species that are overt human and animal pathogens . The mitis group includes commensals of the human oral cavity and pharynx, except S. pneumoniae The anginosus and salivarius groups are part of the commensal microbiota of the oral cavity and pharynx. The bovis group belongs in the colon. The mutans group of streptococci colonizes exclusively the tooth surfaces of man and some animals; some cause dental caries .

9. Streptococcus pyogenes Group A beta-hemolytic streptococci Most important human pathogen of the genera causes a wide range of suppurative infections in the respiratory tract and skin, life-threatening soft tissue infections, and certain types of toxin-associated reactions Non-motile, non sporing , oval cocci , 0.6-1 In short chains, long in broth  

10. Cultural characters Aerobic/facultative anaerobes, 37 C, pH 7.2 – 7.4, fastidious nature, 5-10% CO2 Culture media : enriched media are required: BAP Selective media: CV-BAP, PNF ( polymyxin -neomycin- fusadic acid media) T. media : Pikes T.M . with CV and sodium azide

11. On BAP ; small, white-gray , pinpoint, 0.5 – 1mm , yellow, semi-transparent to opaque, matt or glossy , mucoid if capsulated, beta-hemolysis On CV-BAP and PNF ; same as BAP with golden yellow color

12. Biochemistry Tests Result Grm. Staining Catalase CAMP Hemolysis PYR Urease VP 6.5% NaCl growth Motility Ribose fermentation Bacitracin sensitivity Bile solubility +ve, cocci , chain -ve -ve Beta +ve -ve -ve -ve -ve -ve +ve -ve

13. Virulence factors Cell wall associated proteins and polymers Enzymes Toxins Cell wall associated proteins and polymers Capsule - prevents phagocytosis 2. Lipo -Teichoic acid( LTAs ) - binds to epithelial cells 3. M proteins - Adhesin and antiphagocytic 4. F proteins – mediate attachment

14. Enzymes 1. Streptokinase - Breaks down the fibrin barrier 2. Deoxyribonucleases - Depolymerizes free DNA present in the pus 3. Hyaluronidase – hydrolyze hyaluronic acid in matrix

15. TOXINS (most important in pathogenesis) 1 . Streptococcal pyrogenic exotoxins ( SPEs ) - Dissolves the clot, thrombi, and emboli 2 . Streptolysin O and Streptolysin S- Lyse erythrocytes, leukocytes, and platelets; and stimulate production of lysosomal enzymes 3. Pyrogenic exotoxins - Release large amounts of cytokines from helper T cells and macrophages; rapidly destroy tissues

16. Pathogenesis Most common entry route is U RT Most common route of infection is respiratory droplets or direct contact with infected sores or wounds

17. Clinical spectrum (Diseases) Suppurative Streptococcal Disease 1. Pharyngitis (5-15% adult, 20-30% children ) 2. Pyoderma

18. 3. Erysipelas 4. Necrotizing fascitis 5. P uerperal sepsis

19. b) Toxin Mediated Diseases 1. Scarlet fever 2. Streptococcal toxic shock syndrome

20. c )Non- suppurative Streptococcal Disease 1. Acute Glomerunephritis ( AGN ) 2 . Acute rheumatic fever ( ARF )

21. Laboratory diagnosis Specimens; Throat swab, nasal swabs , high vaginal swabs (puerperal sepsis), pus or pus swabs , pharyngeal secretions, blood, CSF, joint aspirate , edge aspirate of cellulitis, skin biopsy specimen , epiglottic secretions, bronchoalveolar lavage fluid , thoracocentesis fluid, or abscess fluid 2 . Microscopy 3 . Culture 4. Biochemical test 5. Direct antigen test 6. Serodiagnosis Done mostly for AGN and ARF

22. Treatment Though responsible for severe and dangerous diseases as already seen in pictures GOOD thing is that it can be cured by PENICILLIN No resistance to PENICILLIN is known till date Erythromycin and clindamycin are choice for Penicillin allergic patient

23. Other pathogenic Streptococcus S. pneumoniae S. agalactiae S. mutans S. mitis S. anginosus S. sanguinis S. suis S. gallolyticus

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