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C occi

C occi. C occi. 5 pathogenic cocci/ pyogenic cocci - G+: staphylococcus S. aureus streptococcus S. pyogenes, S. pneumoniae - G-: Neisseria N. meningitidis, N. gonorrhea. (I) Staphylococcus. Staphylococcus.

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C occi

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  1. Cocci

  2. Cocci • 5 pathogenic cocci/ pyogenic cocci • - G+: staphylococcus • S. aureus • streptococcus • S. pyogenes, S. pneumoniae • - G-: Neisseria • N. meningitidis, N. gonorrhea

  3. (I) Staphylococcus

  4. Staphylococcus Primary reservoir -Human carriers -Nasopharynx, throat, skin >30 species - main bacteria in the nosocomial infection - S. aureus: the most virulent species - S. epidermidis: opportunistic pathogen - S. saprophyticus: rarely cause human diseases

  5. Comparison

  6. Biological characteristics • Grape like-clusters, no capsule • Facultative anaerobes • Liposoluble pigments • Hemolysis • Resistance

  7. Pathogenicity (S. aureus) • Virulence factors • invasiveness - surface structure SPA - invasive enzymes coagulase • Toxin---exotoxins - hemolysins/ Staphylolysin - leukocidin - Staphylococcal enterotoxin - toxic shock syndrome toxin-1, TSST-1 - exfoliative toxin/ epidemolytic toxin

  8. SPA inhibits phagocytosis PHAGOCYTE Fc receptor SPA IgG Fab Fc BACTERIUM Free protein A binds to Fc of IgG, blocking Fc receptors and is thus anti-phagocytic.

  9. Pathogenicity (S. aureus) • Disease • Invasive infection/ pyogenic infection - local infection: lesion is limited in local area -organ infection: pneumonia, meningitis - systemic infection: septicemia, pyemia Bactermia (from abscess, wound, burn) , Osteomyelitis (tibia) ,Pneumonia

  10. folliculitis Boil/ furuncle

  11. carbuncle Impetigo---staph skin infection, multiple pustules (small skin abscesses)

  12. Pseudomembranous Colitis PseudomembranousEnteritis,PME

  13. Pathogenicity (S. aureus) • Disease • Toxin-associated diseases - food poisoning (enterotoxin) - TSS (TSST-1) sudden high fever, shock, kidney failure, red skin rash - SSSS (exfoliative toxin) staphylococcal scalded skin syndrome - staphylococcal enterocolitis- dysbacteriosis

  14. Staphylococcal scalded skin syndrome (SSSS) • - most often occurs in infants and young childrenLow mortality rate Skin blister---denudation (like scald)

  15. Laboratory diagnosis • Direct examination: Gram Stain • Primary media: BAP • Differential Tests. Mannitol Salts Coagulase DNase Enterotoxin • Antibiotic Sensitivity (plasmid, B lactamase) : penicillin /methicillin/vancomycin API STAPH Kit

  16. Staphylococcus epidermidis coagulase negative staphylococci • Major component skin flora • Opportunistic infections (less common than S.aureus) • urinary tract infection (UTl) • septicemia • wound infection • Nosocomial infections • bacterial endocarditis • Identification • Non-hemolytic (sheep blood agar) • Does not ferment mannitol • Coagulase-negative Staphylococcus saprophyticus • urinary tract infections

  17. (II) Streptococcus • Widely exist: • -water, air, feces, human nasopharynx • Diseases: • -pyogenic infection • - scarlet fever • -streptococcal hypersensitive disease • - rheumativ fever

  18. (II) Streptococcus - G+, arranged in chains - Nutrient requirement: high *fastidious (flesh-eating bacteria) - Facultative/ obligate anaerobe - On blood agar: *different hemolysis - Catalase negative (staphylococci +)

  19. Classificaton • based on hemolytic activity - α-hemolytic strep incomplete hemolysis opportunistic pathogens - β-hemolytic strep complete hemolysis main human pathogens -γ-hemolytic strep no hemolysis no pathogenicity

  20. Hemolysis alpha beta gamma

  21. Classificaton • Antigenic structure - polysaccharide antigens (C Ag) *group-specific antigen * 20 groups (A-H, K-V) * group A main human pathogens - surface protein antigens (M Ag) * type-specific antigen * group A>80 serotypes

  22. Pathogenicity (Step. Group A) • Virulence factors • Surface structure - LTA: adhere to host cells - M- protein - Peptidoglycan

  23. Lipoteichoic Acid and F-protein lipoteichoic acid F-protein fibronectin epithelial cells

  24. r r r r r r M protein IMMUNE Complement IgG M protein NON-IMMUNE peptidoglycan fibrinogen

  25. Pathogenicity (Step. Group A) • Virulence factors • Invasive enzymes - hyaluronidase (spreading factor) - streptokinase (SK) - streptodornase (SD) • Toxins---exotoxins - streptolysin (hemolysin) - erythrogenic toxin • Erythrogenic toxins ---pyrogenic exotoxin scarlet fever toxin - protein - serotype A, B, C - scarlet fever

  26. streptolysins

  27. Anti-SLO test (ASO test) • A neutralization test between the toxin (SLO) and its specific anti-toxin (ASO) which is used to diagnose or monitor rheumatic fever caused by group A strep.

  28. Pathogenicity (Strep. Group A) • Disease • 3 types of infections - pyogenic infection: skin & subcutaneous infection, impetigo, lymphangitis, septicemia - toxin-associated diseases pharyngitis--scarlet fever - hypersensitive disease acute glomerulonephritis, rheumatic fever

  29. Erysipelas on the cheek Abscess with surrounding cellulitis Acute tonsillitis--- There is a risk of developing rheumatic fever Erysipelas pyogenic infection

  30. Strawberry tongue Red rash Paly around mouth toxin-associated diseases

  31. Diseases caused by other streptococci Group B strep. - neonatal infection - adult infections: endometritis, pneumonia, meningitis, endocarditis Group C strep. - epidemic sore throat, acute glomerulonephritis Group G strep. - sore throat, cellulitis, erysipelas Group D strep. - nosocomial infection, urinary infection, biliary tract infection, peritonitis

  32. Laboratory diagnosis • Direct examination: Gram Stain • Primary culture • ASO Tests.

  33. Prevention and treatment Treat the pharyngitis and tonsillitis in time Antibiotics: penicillin for the first choice

  34. (III) Pneumococcus

  35. Characteristics • Morphology & cultivation properties - G+, arranged in pairs, bullet shape - capsule: polysaccharide - blood agar or chocolate blood agar, festidious - α-hemolysis - autolysis - bile solubility test: + *distinguish from other α-hemolytic strep. - ferment inulin

  36. Pathogenicity • Virulence factors - capsule - pneumolysin & neuraminidase - Surface protein adhesin and secretory IgA protease. - Teichoic acid and the Peptidoglycan fragment, phosphorylchorine .

  37. Pathogenicity • Main disease - pneumonia *particularly young and old *after damage to upper respiratory tract e.g. following viral infection - bacteremia - meningitis - middle ear infections (otitis media)

  38. + - Laboratory diagnosis • Differentiate S. pneumoniae from other α-hemolytic strep. - bile solubility test - optochin sensitivity test -capsule swollen reaction - animal test

  39. Treatment & prevention (S. pneumoniae) • Sensitive to a wide range of antimicrobial agents, but resistance is common: penicllin, erythromycin, chloramphenicol, sulphonamides, clindamycin, vancmycin • Prevention polysaccharide vaccine 14 capsule types mixed vaccine

  40. optochin sensitive Not optochin sensitive Bile solubility test Streptex antiserum • Quellung reaction • using antisera • capsule "fixed" • visible microscopically Latex agglutination - streptococci

  41. (IV) Neisseria • Genus Neisseria > 10 species • N. Meningitidis • - meningitis • - low prevalence but high mortality • N. Gonorrhoeae • - human gonorrhea • - high prevalence but low mortality

  42. Polymorphonuclear cells Biological characteristics • G-, coffee bean-shaped or kidney-shaped, in pairs • Capsules and pili • Fastidious • Resistance: very low

  43. Biological characteristics • Oxidase positive • Culture: 5-10% CO2 • Thayer Martin. selective chocolate agar heated blood

  44. Pathogenesis--meningococcus • Virulence factors -pili: attach to nasopharyngeal mucosa -capsule -endotoxin: damage capillary blood vessel • Transmission -respiratory droplets • Disease - epidemic cerebrospinal meningitis

  45. Pathogenesis--gonococcus • Virulence factors -pili -IgA, protease -outer membrane protein (OMP) -LPS • Transmission -sexual contact -indirect contact (basin, towel, etc) • Disease - gonorrhea

  46. N. meningitidis N. gonorrhoeae Virulence Factors Similar, but – Differences in utilization LPS LPS IgA protease Capsule PILI Opacity (OPA) proteins Outer Membrane Proteins Hemolysin IgA protease PILI Opacity (OPA) proteins Outer Membrane Proteins X NO capsule NO hemolysin

  47. Neisseria gonorrhoeae Gram stain of pure culture Urethral exudate Using the Gram stain in patient specimens, the organisms are most often observed in polymorphonuclear leukocytes • After 2-14 days • Found only in man • Gonorrhea: second most common venereal disease

  48. Neisseria gonorrhoeae • adults -transmission: STD (sexually tranmitted disease) -clinical dsease: genitourinary tranct infection urethritis, prostatitis, epididymitis (male) cervix inflammatin (female) infertility • newborns -ophthalmia neonatorum

  49. Neisseria gonorrhoeae Pili = key in anchorage of organisms to mucosal epithelium. Nonpiliated gonococci are avirulent OUTER MEMBRANE PROTEINS Porin proteins (Por)= prevent phagolysosome fusion & allow intracellular survival [ also called protein I] Opacity proteins (Opa)= binding of organisms to epithelium [also called protein II] Reduction-modifiable proteins (Rmp)= protection against bactericidal antibodies [ also called protein III]

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