六年制细菌各论教案-新.doc

Individual Microbiology staphylococcus G+ streptococcus Cocci pneumococcus meningococcus G- Gonococcus Aerobe G- - enteric bacilli Bacilli corynebacterium diphtheria and G+ M.tuberculosis facultative anaerobe Spirillar bacteria -V.cholera obligate anaerobe spore-forming anaerobic bacteria non-spore-forming anaerobic bacteria Content1.biological characteristics2.pathogenicity-pathogenic factor ，phathogenesis3.immunity4.laboratory diagnosis(bacteriological methods)5.prevention and treatmentPathogenic Cocci（pyogenic cocci）G+ cocci Staphylococcus, Streptococcus, Pneumococcus. PurulentG-cocci Meningococcus, Gonococcus. InfectionSection 1. StaphylococcusI. Biological characteristics1. Morphology:Gram positive cocci, arranged in irregular, grape like clusters, capsule in vivo2. Culture:temperature : 2838 (37); pH : 4.59.8 (7.4) colony : 12 mm, circular, smooth, shiny surface, various pigments on blood agar - hemolysis (S. aureus)Major properties of three species of staphylococciMain property Staph. aureus Staph. Epidermidis Staph saprophyticusPigmentation Golden yellow White Citrine Coagulase + _ _Hemolysin + _ _ SPA + _ _ Pathogenicity + -/+ _ 3. Typing : S. aureus have been differentiated into different phage types ( important aspect in the investigation of a infection source) .4. Antigenic structure: (1) SPA (staphylococcal protein A) i) cell wall protein of S. aureas ii) it combines nonspecifically with the Fc-portion of human IgG iii) antiphagocytosis iv)damage platelet; activate B cell v) coagglutination (rapid diagnostic technic) 5. Resistance: resistant to dry; heat (80,30min); salt tolerant (1015% NaCl) Sensitive to antibiotics and sulfonamides , but drug- resistance are easily produced II. Pathogenicity1. Pathogenic factor1).Invasiveness(1)Surface structure: SPA - anti-phagocytosis , Lipoteichoic acid, LTA - adherence (2) Enzyme:Coagulase: An enzyme which causes coagulation in plasma containing an anticoagulant such as citrate, coagulase is found in all pathogenic strains of Staphylococci. Roles : to inhibit the phagocytosis of phagocytes and damage of bacteriacide substances in humor by coating the organisms with fibrin.two types of coagulase:(1).Free coagulase - an extracellular enzyme which converts fibrinogen in citrated plasma into fibrin. (in tube)(2).Bound coagulase - a bound coagulase in the cell wall that induces clumping of organisms in the presence of fibrinogen. (on slide) 2)Toxin- exotoxin(1) . Staphylolysin: cytotoxic effects on phagocytic and tissue cells. kinds: a-Lysin ; b-Lysin; g-Lysin; d-Lysin Staphylolysin-a: main pathogenic substance, form hemolysing-ring around the colony(2) .Leukocidin: Kill PMNs and MF (3). Enterotoxin: Protein; Nine types: A-E, G; Heat stable (boiling for 30 min) Cause a food poisoning characterized by severe vomiting and diarrhea (4). Exfoliative toxin: Cause Staphylococcal scalded skin syndrome (SSSS) (5). Toxic shock syndrome toxin-1 (TSST-1): Cause Toxic shock syndrome (TSS):2. Pathogensis1) Purulent infection (1). local infection (skin infection): hair folliculitis; boil; carbuncle; impetigo. ( characterised by thick pus and a limited local area ) (2).organ infection: pneumonia, meningitis. (3).systemic infection: septicemia; pyemia2) Toxin diseases(1). Food poisoning : enterotoxin in contaminated food(2). TSS (Toxic shock syndrome): (3). SSSS(staphylococcal scalded skin syndrome):III. Immunity: not stable IV. Laboratory diagnosis specimen: pus sputum (low respiratory tract infection) blood (septic shock, osteomyelitis, endocarditis) mid-stream urine (pyelonephritis or cystisis)food/faeces or vomit (food poisoning) *direct smear : Gram stain ( initial diagnosis ) *isolation and identification: blood agar *coagulose test: * antibiotics test : *enterotoxin test and animal test: food poisoningIV. Treatment: Antibiotic therapy: but antibiotic resistance can arise . eg: Resistance to penicllin ( penicillinase ) NOTE: antibiotic sensivity testCoagulase-negative staphylococci (CNS)CNS - Normal flora (Staph. Epidermidis ; Staph saprophyticus)- Major causes of hospital-acquired infectionSection 2. StreptococcusI. Biological characteristics1.Morphology & cultural properties:(1) G+ cocci, arranged in chains, no special structure(capsule of hyaluronic acid in the early period).(2) high nutritive requirement (blood & serum)blood agar: *tiny colony (f 0.50.7 mm) * hemolyze erythrocytes in vitro in varying degrees2. Classsification: It is classified based on the hemolyzation phenomenon and antigenic structure.(1).Hemolytic activity:(i) a-hemolytic streptococcus (streptococcus viridans)*Incomplete hemolysis, green colotation of the medium surrounding the colony. *Opportunistic pathogens subacute bacterial endocarditis (SBE).(ii) b-hemolytic streptococcus (or pyogenic streptococcus)Complete hemolysis, major human pathogens (iii) g-streptococcusNo hemolyzation, no pathogenicity on most cases(2).Antigenic structure:(i) polysaccharide antigen (group-specific antigen). 20 groupsGroup A streptococci are main human pathogens(ii) protein antigen (type-specific antigen).M protein: presents in cell wall (group A streptococci ) ,the main virulence factor3.Resistance *heat labile: 60,30 min*antibiotics sencitivity: panicillin G ,etc.II. phathogenicity1. Pathogenic substances (invasiveness & exotoxin):(1). Invasiveness(i) adhesin *LTA (lipoteichoic acid): adhere to sensitive cell *M protein: the main virulence factor*presents in cell wall (group A streptococci ) *adhere to epithelial cells * antiphagocytosis * is related to post-streptococcal hypersensitive disease (rheumatic fever and acute glomerulonephritis )Common antigen exists between M-protein and human myocardial cell - type II hypersensitivity - rheumatic feverMAg -Ab Immune complex - type III hypersensitivity - acute glomerulonephritis(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(2).Toxins -exotoxin(i)Streptolysin: * Destroy blood cells and tissues cells * Two kinds: Streptolysin O(SLO): oxygen-labile, high antigenicity - induce antistreptolysin O (ASO) Streptolysin S (SLS) oxygen stable - responsible for the hemolysis, weak antigen (ii) pyrogenic toxin (or Erythrogenic toxin /scarlet fever toxin) *produced by most strains of group A streptococci *cause scarlet fever *possess antigenicity, antitoxin specifically neutralize the toxin2. Diseases of streptococcal infection1). Infections of group A (b-hemolytic streptococci)(1). local purulent infections: pharyngitis, erysipelas, puerperal fever;(thin pus; infection may spread quickly)systemic infection: septicemia(2). Toxin-mediated disease: scarlet fever(3). Poststerptococcal diseases (hypersensitive disease)(i) Acute glomerulonephritis ( group A streptococci) Mechanism: *type III hypersensitivity (most) *type II hypersensitivity M protein-Ab Immune complex common Ag deposition glomerular basement membrane cross reacts with activationC3,C5 glomerular basement membrane tissue destruction tissue destruction (ii) Rheumatic fever (many types of group A streptococci) Mechanism: *immune complex (deposition) heart, joints type III hypersensitivity *common Ag cross-reacts heart type II hypersensitivity 2) Infections of a-hemolytic streptococci: normal flora : throat/nasapharynS. mutant - dental plaque/caries, S.bovis-septicemia, S. anginosus- subacute bacterial endocarditis (SBE).IV. ImmunityV. Laboratory diagnosis1. Isolation & identification of pathogen2. ASO test: ASO titer 1: 400 units, help to diagnose rheumatic fever.VI. Prevention & treatment*Treat the pharyngitis and tonsillitis in time, avoid the post streptococcal diseases.*Antibiotics and chemical agents: penicillin G for the first choiceSection 3. Pneumococcus 1. Belong to the Streptococcus ( Streptococcus pneumoniae ), 2. G+, diplococcus, lancet shape, arranged in pair, capsule of polysaccharide 3. Blood agar, 0.1% glucose, 515%CO24. small colony, - haemolysis, smooth colony (virulent strain)， amidase 5. Pathogenic factor: capsule( antiphagocytosis)6. Disease: lobar pneumonia 7. Identification: distinguished from a-streptococcus8. Prevent and Treatment: capsule polysacchride vaccine: 23typessensitive to a wide range of antimicrobial agent. eg.Penicillins*,Section 4. NeisseriaCommon biological characteristics1.Gram negative cocci, kidney-shaped, in pairs have capsules and pili, 2.Need enriched medium (chocolate blood agar ) and 510%CO2,3. Resistance: very weak “fragile”, extremely sensitive to drying, heat, cold4. Human pathogens: Gonococcus , Meningococcus Neisseria gonorrhoeae(gonococcus)1. Pathogenic factors:* Pilli: attach to epithelial cells (urinary-gentital)*Outer membrane protein (OMP): adhere *Lipooligosaccharide (LOS): similar to LPS 2. Diseases: Human is the only natural host, sexually transmissionGonorrhea: sexually transmitted disease (STD)acute urethritis(male); pelvic inflammatory(female)*ophthalmia neonatorum blindness3. Laboratory diagnosis: Specimen: purulent secretion of genitourinary tract Isolation and identification: direct smear, culture, biochemical tests, EIA,4. Prevention and treatment *penicillin- Gonorrhea*silver nitrate- ophthalmia neonatorumNeisseria meningitidis1 Pathogenic factors:*Pili attach to nasopharyngeal mucosa *capsule antiphagocytosis*endotoxin main pathogenic substance 2 Diseases: Human is the only natural host，Child: susceptible (lacking specific Abs)* Epidemic cerebrospinal meningitis （respiratory tract transmission）3. Immunity:group-specific antibody, cross-immunity between groups.4. Laboratory diagnosis Specimen: cerebrospinal fluid (CSF), blood,*note: “fragile” bed-side inoculationDirect smear : smear Gram stain (G- diplococci, within white cells)Isolation and identification:specimen serum broth chocolate blood agar plate (510% CO2 ,37C ) Gram stain and biochemical, serological identification Ag detection（rapid diagnosis）: ELASA, coagglutination 5 Prevention and treatment1. Polysaccharide vaccine (group A, C)2. Penicillin; Enteric BacilliI. Common properties:1. Similar shape: G- rods, most possess flagella and pilli. No spores, certain members possessing capsules.2. culture: aerobe or facultative, basic agar, 2-3mm colonies 3. Biochemical reactions are active and diverse.Many kinds of carbohydrates and proteins can be utilized and form various products.Differentiation: e.g. Lactose fermenting bacteria enteric nonpathogens Non-lactose fermenting bacteria enteric pathogens4. antigenic structure is complex(1) O antigen - specific polysaccharides of LPS Basis of serological classification (2) Surface Ag: - Polysaccharides that cover the O Ags (e.g. capsule Ag) Main surface Ags: Vi antigen (S. typhi), K antigen (E. coli) Inhibit specific agglutination of O antiserum Associated with invasiveness of enteric bacilli(3) H Ag - flagella protein:Basis of serological classification. 5. some members produce bacteriocin6 Produce endotoxins and/or exotoxinsSection I. Escherichia coliI. Biological characteristics: 1. Shape and structure: G- rods, possess flagella and pilli. 2 .Biochemical reactions (extremely active and complex): (1) Lactose fermentation test: “+” On differential media : colored colony (2) IMViC test: + + - -3. Antigenic structure: O Ag- more than 170, cross -rection H Ag - more than 56, specific (flagellar) K Ag (L, A and B) - more than 100e.g. serotype is expressed as O111:K58 (B4):H2II. Pathogenicity1. pathogenic factors(1) invasiveness: K Ag; Pili; CFA (colonization factor Ag)Specifically adheres to the epithelial cell lining the small intestine(2) O Ag, K Ag: anti-complement; anti-phagocyte(3) endotoxin: cell wall lipopolysaccharide ; fever / shock(4) enterotoxin (exotoxin): consists of LT and ST LT (heat labile enterotoxin): similar to Cholera enterotoxin (A subunits and five B subunits )- stimulates adenylate cyclase cAMP - diarrheaST(heat stable enterotoxin): stimulates cGMP - diarrhea 2. Infection (1). extraintestinal infections - caused by E. coli opportunistic pathogens *urinary tract infection (the most common ) *G- bacteremia ;septicemia * neonatal meningitis (new born) (2). diarrheal diseases-caused by certain serotypes of E.coli Enterotoxigenic E.coli (ETEC) LT and/or ST; Diarrhea; children(under 5 years), adult(travellers), Nausea, vomiting, abdominal cramps Enteropathogenic E.coli (EPEC) No exterotoxin; Diarrhea; infantile enteritis severedeath Less in adults Enteroinvasive E.coli (EIEC) No exterotoxin; endotoxin, Diarrhea, like dysentery;( large intestine) Children, adults Enterohemorrhagic E. Coli (EHEC)vero toxin, hemorrhagic colitis; HUSIII. Laboratory diagnosis1. Specimen: feces, blood, pus, etc2. Isolation and identification: * Biochemical reactions* serologic identificationIV. Investigation in public health bacteriology indicator of fecal pollution (food/water) 1.Detecting number of coliform bacteria: Normal number 3 / 1000 ml sample. 2.Detecting total number of bacteria: Normal number 100 colonies / ml (g) sample.V. Treatment and controlSection 3. ShigellaI. Biological characteristics1. G- rods, non-motile, possesses pili2. biochemical reaction lactose fermentation: test: “-”(only shigella sonnei late fermentation), On differential media : non color colony3. antigenicity: O Ag, K Ag4. Classification: 4 groups, 43 serotypes 5. Variation: antibiotic-resistance (R plasmid); II Pathogenesis and Immunity Human beings the only natural hosts1. Pathogenic factor: Infecting dose: 200 organisms (1).Pili adhesion ileum intestinum end epithelial cell(2).Endotoxin fever, shock; inflammatory; rectal cramp(3).Exotoxin: shiga toxin (vero toxin-I, II)2.Disease : organisms oral route , patient/ carrier, *acute dysentery (bacillary dysentery) : fever, bloody mucopurulent stool, abdominal cramp, tenesmus , local inflammation ulceration( colon) *chronic dysentery : diarrhea : carrier * 中毒性菌痢唐伟请加上英文3.ImmunityIgA persistent short, no IgGIII. Laboratory diagnosis1.Isolation and identification2.Rapid diagnosisIV.prevention and TreatmentSection 4. SalmonellaI. Biological characteristics:1 G-, peritrichous, non spore-forming, lactose fermentation: test: “-”Biochemical reactions: -the basis of classification and identification2.Antigenic structure and classification (1). O antigen (2). H antigen Type specific Ag: a. Phase 1 specific phase b. phase 2 nonspecific phase (3). Vi antigen (virulent Ag) surface polysaccharide; antiphagocytosisII. Pathogenesis and immunity1. Pathogenic factors(1) Invasiveness Pili-adherence Vi antigen -antiphagocytosis(2) Endotoxin WBC; shock ; activited complementinflammation(3) Enterotoxin S.typhi murium: LT/ST2. Pathogenesis(1) Septicemia: (S. Choleraesuis) Pneumonia; osteomyelitis; meningitis(neonates, very young child)(2) Enterocolitis (Food poisoning) World wide; incubation period: 6-24 hour headache, abdominal pain, nausea, vomiting, fever , watery diarrhea(3) Enteric fever: Organism typhoid (caused by S. typhi) paratyphoid (caused by S. Paratyphi A,B,C) Characteristics of the disease: two times of bacteremia, continuous fever, liver and spleen enlargement, rose spots, severe complications.3. ImmunityEnteric fever: *persistant immunity after disease. *The main anti-infectious immunity is CMI. *humoral im