Cocci

1. Cocci

2. Staphylococcus “staphyle” in Greek

3. Staphylococcus • S.aureus: most virulent species. • S.epidermidis: opportunistic pathogen. • S.saprophyticus: rarely cause human diseases.

4. Biological characteristics • Shape and structure • Size: 0.5-1.0 m in diameter • Shape: spherical • Arrangement: grape-like • Structure: capsule non-motile non-sporulating • Staining: G+

5. Biological characteristics • Cultivation • Requirements media: all-purpose media gas: facultative anaerobes specially: tolerating 10-15% NaCl

6. Biological characteristics Growth properties on solid medium: small colony with various pigments on blood agar: zone of complete hemolysis (-hemolysis) S.aureus

7. Biological characteristics • Biochemical reactions Catalase test “+” Staphylococci: “+” Streptococci: “-” Mannitol Fermentation “+” S. aureus: “+”; S.epidermidis & S.saprophyticus: “-”;

8. capsule peptidoglycan teichoic acid SPA Biological characteristics • Antigenic composition Capsules teichoic acid , peptidoglycan Protein antigen: SPA

9. Characteristics nonspecific bind to the Fc fragment of IgGs SPA (Staphylococcal Protein A )

10. SPA(staphylococcal protein A) • Function: • virulence factor • Anti-phagocytosis • damage platelet • induce hypersensitivity and inflammation Phagocyte Fc receptor IgG SPA • coagglutination test SPA-coated S.aureus is used as Ab carriers BACTERIUM

11. S.aureus Ab SPA (staphylococcal protein A )

12. Properties S. aureus S. epidermidis S. sarprophyticus Pigment Golden yellow White Citrine Coagulase + － － Mannitol + － － Thermostable nuclease + － － α-hemolysin + － － SPA + － － Pathogenicity strong Weak - Biological characteristics---Classification • Based on the pigments and chemical reactions

13. Biological characteristics---Classification • Based on coagulase • Coagulase” +”: e.g., S. aureus • Coagulase” -”: e.g., S. epidermidis & S. saprophyticus • Phage typing S. aureus: 3 phage groups, 26 phage types. • group 1: TSST-1-producing strains • group 2: exfoliative toxin-producing strains • group 3: enterotoxin-producing strains ----is of epidemiological value

14. Biological characteristics • Resistance: • Drying • Heat • high concentration of salt (10-15% NaCl) • Sensitivity: • basic dyes (crystal violet) • several antibiotics (penicillin, vancomycin) MRSA (methicillin resistance S.aureus)

15. Virulence factors Surface structure capsules, peptidoglycan, teichoic acid, SPA Enzyme Toxin Pathogenicity (S.aureus)

16. Pathogenicity (S.aureus) • Virulence factors Enzymes:coagulase血浆凝固酶 heat-stable nuclease 耐热核酸酶 hyaluronidase 透明质酸酶 lipase 脂酶 β – lactamase β-内酰胺酶 Exotoxins: Hemolysin溶血素 Leukocidin杀白细胞素 Staphylococcal enterotoxin葡萄球菌肠毒素 TSST-1毒性休克综合征毒素-1 Exfoliative toxin表皮剥脱毒素

17. Enzyme • Coagulase: • An enzyme that converts fibrinogen into fibrin causing the coagulation of blood. • Classification: Free coagulase 游离凝固酶 Bound coagulase 结合凝固酶

18. Coagulase • Biological activity Antiphagocytosis Inhibit the damage of bactericidal substances Formation of limited abscess • Significance criterion for identification of S. aureus (pathogenic)

19. Coagulase test Tube test for free coagulase Slide test for bound coagulase

20. Hemolysins • Roles: damage membrane permeability; cytotoxic effects on phagocytes and tissue cells • Four kinds: -Lysin -Lysin -Lysin -Lysin S.Aureus in blood agar

21. Leukocidin • Biological activity Impairment of membrane of WBC

22. Staphylococcal enterotoxin • Source: 50% S. aureus • Types: A、B、C1-3、D、E、G、H • Chemical and physical characteristics Protein Heat stable (100℃, 30 min) Resistant to gut enzymes • Mechanism: act on vomiting center, superantigen • Disease: food poisoning

23. Superantigens and the non-specific stimulation of T cells

24. Toxic Shock Syndrome Toxin-1(TSST-1) • Source:phage group Ⅰ of S. aureus • Biological activity fever Increase the sensitivity to endotoxin superantigen • Disease: TSS

25. Exfoliative toxin • Source phage group Ⅱ of S. aureus • Biological activity protease activity • Disease: SSSS Staphylococcal scalded skin syndrome

26. Pathogenicity • Disease • Invasive infection/pyogenic infection • local infection: folliculitis; boil ; carbuncle ; impetigo • organ infection: pneumonia; meningitis • Systemic infection: Septicemia; pyemia • Toxin-associated diseases

27. hair folliculitis boil

28. Pathogenicity • Toxin-associated diseases • Food poisoning (enterotoxin) • TSS (Toxic shock syndrome) • SSSS (staphylococcal scalded skin syndrome) • Staphylococcal enterocolitis -dysbacteriosis

29. Staphylococcal scalded skin syndrome (SSSS) Most often occurs in infants and young children

30. CNS • Coagulase-Negative Staphylococci • Virulence factor: slime • Antibiotic-resistance • Opportunistic infection • S. epidermidis, S.saprophyticus

31. Diseases caused by coagulase-negative staphylococci • Diseases: • urinary tract infection • Bacterial endocarditis • Septicemia • Infections associated with indwelling devices

32. Laboratory diagnosis • Specimen • Direct smear and Gram stain • Isolation and identification Primary criterions: coagulase test, thermostable nuclease gold yellow pigmentation -hemolysis mannitol fermentation • Enterotoxin test (animal test) • Antibiotic susceptibility tests

33. Control Nosocomial infection Aseptic measures Prevention Drug resistance hygiene Treatment Autovaccino-therapy Antibiotic susceptibility tests

35. Streptococcus

36. capsule cell membrane cell wall pilus-like structure • Shape: G+cocci in chains • structure:capsule pilus-like (LTA-M protein) carbohydrate antigen protein antigen: M, R, T carbohydrate antigen and protein antigen

37. Classification • Hemolytic activity • -hemolytic strep. Incomplete hemolysis Opportunistic pathogens e.g., S.pneumoniae, S.viridans • -hemolytic strep. Complete hemolysis() Major human pathogens e.g., S. pyogenes • -streptococcus No hemolysis, No pathogenicity e.g., enterococci.

38. a b c

39. Classification • Antigenic structure ( Lancefield 血清学分群) • C carbohydrate antigen • group-specific antigen • 20 groups (A~H, K~V) • Group A- main human pathogens • Protein antigen • type-specific antigen • M, R, T protein • Group A >100 types Cell wall Streptococcus capsule protein Polysaccharide Peptidoglycan

40. Classification • Biochemical reaction

41. S. pyogenes

42. Biological characteristics • shape and size: spherical, 0.6～1.0 μm in diameter structures: capsule (hyaluronic acid) nonmotile nonsporeforming highly nutritive -hemolysis catalase negative

43. Pathogenicity • Virulence factors Surface structures Enzymes Exotoxins

44. Pathogenicity • Virulence factors Surface structures adhesin: LTA F protein M protein: anti-phagocytosis cross-reactive antigen lipoteichoic acid F-protein M protein fibronectin epithelial cells

45. Pathogenicity • Virulence factors Enzymes Hyaluronidase Streptokinase (SK) Streptodornase(SD) (DNase, DNaseB-Ab)

46. Pathogenicity • Virulence factors Exotoxins Streptolysin (hemolysin) Erythrogenic toxin

47. Streptolysins • streptococci group A, C, and G; • Classification:

48. Erythrogenic toxin • Pyrogenic toxin /scarlet fever toxin • Protein • Antigenicity • Superantigen • Scarlet fever

49. Abscess with surrounding cellulitis Pathogenicity • Pyogenic infection: • Local purulent infections pharyngitis, tonsillitis, puerperal fever 产褥热 erysipelas 丹毒, cellulitis 蜂窝织炎 impetigo • Systemic infection: septicemia

50. Erysipelas Erysipelas on the cheek