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病原生物学教研室 Department of pathogenic Biology of Gannan Medical University

医学微生物学 Medical Microbiology. 病原生物学教研室 Department of pathogenic Biology of Gannan Medical University. 张文平. Chapter 10. Pyogenic bacterium. Pyogenic cocci 化脓性球菌. Gram-positive cocci Staphylococcus aureus 金黄色 葡萄球菌 Streptococcus pyogenes 化脓性 链球菌 Streptococcus pneumoniae 肺炎链球菌

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病原生物学教研室 Department of pathogenic Biology of Gannan Medical University

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  1. 医学微生物学 Medical Microbiology 病原生物学教研室 Department of pathogenic Biology of Gannan Medical University 张文平

  2. Chapter 10 Pyogenic bacterium

  3. Pyogenic cocci化脓性球菌 • Gram-positive cocci Staphylococcus aureus 金黄色葡萄球菌 Streptococcus pyogenes 化脓性链球菌 Streptococcus pneumoniae 肺炎链球菌 • Gram-negative cocci Neisseria meningitides 脑膜炎奈瑟菌Neisseria gonorrhoeae 淋病奈瑟菌

  4. Pyogenic bacillus化脓性杆菌 • Gram-negativebacillus Pseudomonas aeruginosa铜绿假单胞菌 Escherichia coli大肠埃希菌属 Proteus 变形杆菌

  5. Staphylococcus 葡萄球菌

  6. Biological character • morphology • culture • Biochemical tests • typing

  7. morphology G+, mainly arranged in grape-like clusters

  8. Gram staining

  9. Culture Individual colonies are circular, 2-3mm in diameter with a smooth, shiny surface;appear opaque and are often pigmented Staph. aureus Golden-yellow pathogenic Blood agar plate opportunists Staph. epidermidis white opportunists fawn Staph. saprophyticus

  10. Colonies of Staph. Aureus and Staph. epidermidis

  11. Important properties • All staphylococci produce catalase（触酶） • H2O2 →O2 + H2O • S aureus coagulase Mannitol fermentation

  12. staphylococcus A protein ，SPA Binds to the Fc portion of IgG at the complement-binding site Significance • Preventing the activation of complement • anti-phagocytic • coagglutination

  13. resistance Resistant to dry, heat , salt

  14. Pathogenesis LTA Virulence factors Invasive enzyme : coagulase toxin：lysin（αβγ ） leucocidin epidermolytic toxins enterotoxins TSST-1

  15. Enterotoxin 肠毒素 • Cause vomiting and watery, nonbloody diarrhea • Superantigen • Heat-resistant 100℃ 30min

  16. Toxic shock syndrome toxin 1毒素休克综合征毒素-1 • Cause toxic shock • Tampon–using menstruating women • Individuals wit h wound infection • Patients with nasal packing used to stop bleeding from the nose • superantigen

  17. Exfoliatin 表皮剥脱毒素(epidermolytic toxins) • Cause scalded-skin syndrome in young children • Acts as protease(蛋白酶) that cleaves desmosome(桥粒)，leading to the separation of the epidermis at the granular cell layer

  18. coagulases • Free coagulase Converts fibrinogen in citrated plasma into fibrin • Bound coagulase reacts with fibrinogen to inhibit the phagocytosis of macrophages and damage of bactericide substances in humor by coating the organisms with fibrin

  19. infections • 1)purulent infection (1). local infection skin infection: hair folliculitis; boil（疖）; carbuncle(痈); impetigo（脓疱病）. (think pus; limited local area) (2).organ infection: pneumonia; meningitis（脑膜炎）

  20. Infections (3).Systemic infection: Septicemia; pyemia 2) Toxin diseases (1). Food poisoning (enterotoxin) (2). TSS(Toxic shock syndrome) (3). SSSS(staphylococcal scalded skin syndrome): 3) Staphylococcal enteritis

  21. (ii) Food poisoning. • The food becomes contaminated with the • organism from human contact, grows and • produces enterotoxin. • The organism does not "infect" on ingestion • of food. • Onset and recovery both occur within a few • hours. • Vomiting, nausea, diarrhea and abdominal pain are present.

  22. (v) Toxic shock syndrome particularly after tampon use includes: • fever • rash（皮疹） • desquamation（脱屑） • vomiting • diarrhea • Toxic shock toxin is involved. • The organism does not disseminate. • However, the toxin does and is responsible for the clinical features.

  23. Laboratory diagnosis specimen: *pus * sputum (low respiratory tract infection) * blood (septic shock, osteomyelitis, endocarditis) * food/faeces or vomit (food poisoning) * mid-stream urine (pyelonephritis肾盂肾炎or cystitis膀胱炎)

  24. Laboratory diagnosis *direct smear :gram stain *isolation and identification: blood agar *coagulase test *Enterotoxin test and animal test *Mannitol fermentation

  25. streptococcus 链球菌

  26. streptococcus

  27. Biological character G+，arranged in chains of varying length culture α-hemolytic streptococci hemolytic streptococci β- Blood agar plate streptococci γ- groups polysaccharide M antigen R Surface protein antigen S T

  28. Classsification: • -hemolytic streptococcus (1).Hemolytic activity: Incomplete hemolysis, green zone around colonies *Opportunistic pathogens • -hemolytic/pyogenic streptococcus Complete hemolysis, clear zone around colonies *major human pathogens • -streptococcus No hemolyzation, no pathogenicity.

  29. Classification of -hemolytic streptococcus Antigenic structure: • Polysaccharide antigen (group-specific antigen). 19 groups Group A streptococci are main human pathogens • protein antigen (type-specific antigen). M protein: *presents in cell wall (group A) *Anti-phagocytosis *adhere to epithelial cells *clump platelet and leukocyte *heat stable; acid stable (pH 2)

  30. pathogenesis Hyaluronidas streptokinase Invasive enzyme DNAases LTA Virulance factors attachment M protein Streptolysin (O,S) toxin Pyrogenic exotoxin (scarlet fever toxin)

  31. (1).Invasiveness (i).surface structure *LTA(lipoteichoic acid): adhere to sensitive cell (epithelial cell; platelet; RBC; WBC; lymphocyte; mucous membranes) * M-protein : ◆anti-phagocytotic ◆Common antigen---heart muscle cell (rheumatic fever) 风湿热 ◆M-Ag Ab hypersensitivity(glomerulonephritis) 肾小球肾炎

  32. (ii).enzyme *Hyaluronidase (spreading factor): Splits hyaluronic acids bacteria spread * Streptokinase (SK): Lyse fibrin, prevent plasma clotting bacteria spread * Streptodornase (SD): Resolve DNA bacteria spread

  33. (2).Toxins---exotoxin (i)Streptolysin (hemolysin) StreptolysinO(SLO)Streptolysin S(SLS) oxygen-labile hemolysin oxygen stable O2 O2 (-SH-------S-S-) (-SH------SH) antigenicity-----ASO weak antigen (antistreptolysin O) destroy WBC, pletelet destroy WBC virulence of MΦ, N.C virulence of many tissues

  34. (ⅱ) Erythrogenic toxin (or pyrogenic toxin /scarlet fever toxin) • produced by most strains of group A streptococci • cause scarlet fever • possess antigenicity, antitoxin specifically neutralize the toxin • protien heat stable

  35. Diseases of streptococcal infection 1). Infections of group A -hemolytic streptococci (1). local purulent infections: *pharyngitis,咽炎 *erysipelas 丹毒 *puerperal fever 产褥热 (2). systemic infection : * septicemia *scarlet fever

  36. (3). poststerptococcal diseases (hypersensitive disease) (i) acute glomerulonephritis ( group A) mechanism: *type III hypersensitivity (most)*type II hypersensitivity M protein-Ab common Ag immune complex deposition cross reacts with glomerular basement glomerular Membrane basement membrane activation C3,C5 tissue destruction tissue destruction

  37. (ii) Rheumatic fever (many types of group A streptococci) mechanism: *immune complex  (deposition) heart, joints  type III hypersensitivity *common Ag  cross-reactionheart type II hypersensitivity

  38. Clinical diagnosis Gram stain based on cultures from clinical specimens ASO Serologic methods Normal titer 1:400 Acute glomerulonephritis and acute rheumatic fever.

  39. Prevention & treatment *Treat the pharyngitis and tonsillitis in time, avoid the post streptococcal diseases. *Antibiotics and chemical agents: penicillin G for the first choice

  40. Streptococcus pneumoniae

  41. Streptococcus pneumoniae

  42. S. pneumoniae is a leading cause of pneumonia in • all ages (particularly the young and old), often • after "damage" to the upper respiratory tract • (e.g. following viral infection). • It also causes middle ear infections (otitis media). • The organism often spreads causing bacteremia and meningitis.

  43. S. pneumoniae is α-hemolytic and there is no group antigen. • Direct Gram staining or detection of capsular antigen in sputum can be diagnostic. • The organism grows well on sheep blood agar.

  44. Autolysin • Pneumococci are identified by solubility in bile. • An autolysin (peptidoglycan degrading enzyme) is released by bile from the cell membrane and binds to a choline-containing teichoic acid attached to the peptidoglycan. • The autolysin then digests the bacterial cell wall resulting in lysis of the cell.

  45. The optochin test is a presumptive test that is used to identify strains of Streptococcus pneumoniae. Optochin disks are placed on inoculated blood agar plates. Because S. pneumoniae is not optochin resistant, a zone of inhibition will develop around the disk where the bacteria have been lysed. This zone is typically 14mm from the disk or greater. Not optochin sensitive optochin sensitive

  46. Capsule • This is highly prominent in virulent strains and its carbohydrate antigens vary greatly in structure among strains. • The capsule is anti-phagocytic and immunization is primarily against the capsule. • Capsular vaccines are available for susceptible individuals; immunity is serotype-specific.

  47. Neisseria

  48. Gram negative cocci, usually arranged in pairs. Some are normal inhabitants in respiratory tract. Others are human pathogens (eg: gonococcus,meningococcus ) …

  49. Common biological characteristics 1.Gram negative cocci, kidney-shaped, in pairs have capsules and pili 2.Need enriched medium (chocolate blood agar ) 3. 5~10%CO2 4.Resistance: very weak “fragile”, extremely sensitive to drying, heat, cold

  50. Neisseria meningitidis 脑膜炎奈氏菌

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