医学微生物学英文版教学课件：第8章 IndividualMicrobiology

1、 Individual Microbiology1. biological characteristics Individual Microbiology2. pathogenicity-pathogenic factor phathogenesis3. immunity4. laboratory diagnosis -bacteriological methods5. prevention and treatmentContent G+ cocci Staphylococcus Streptococcus Purulent Pneumococcus Enterococcus G- cocci

2、 Meningococcus infection Gonococcus Pathogenic coccusSection1. Staphylococcus I. Biological characteristics Staphylococcus1.Morphology gram positive cocci, arranged in irregular, grape like clusters；capsule in vivo 2.Culture temperature : 1840 (37); pH : 4.59.8 (7.4) blood agar-haemolysis Colony:12

3、mm, circular, smooth,shiny surface, opaque, various pigments Staphylococcus 3.Classification: Main property S. aureus S. epidermidis S. saprophyticus PigmentationGolden yellow WhiteCitrineCoagulase+- Hemolysin +-Leukocidin+-SPA+-Pathogenicity+-/+- 4. Antigenic structure (1) SPA (staphylococcal prote

4、in A) i) cell wall protein ii) it combines nonspecifically with the Fc-portion of human IgG iii) antiphagocytosis iv) damage platelet; activate B cell v) coagglutination Staphylococcus(2) Capsule polysacchride : adherence, anti-phagocytosis Staphylococcus Staphylococcus 5. Resistance: (1) resistant

5、to: heat (80,30min); salt (1015%); dry, 2-3months in dry pus and sputum (2)sensitivity to: basic-dyes(crystal violet); antibiotics and sulfonamides (antibiotic resistance)II.Pathogenicity Staphylococcus1.Pathogenic factor 1).Invasiveness (1)Surface structure capsule, SPA (2)Enzyme Coagulase: Any bac

6、terial component or product which causes coagulation in plasma containing an anticoagulant. Roles : to inhibit the phagocytosis of macrocytes and damage of bacteriacide substances in humor by coating the organisms with fibrin. associate with pathogenicity of staphylococcus ( pathogenic indicator). S

7、taphylococci produce two types of coagulase: (1) free coagulase (2) Bound coagulase Staphylococcus 2)Toxin-exotoxin (1) Staphylolysin:cytotoxic effects on red blood cells and tissue cells kinds: -Lysin ; -Lysin; -Lysin;-Lysin Staphylolysin-: main pathogenic substance form (2) Leukocidin: Kill PMNs a

8、nd M(3) Enterotoxin: Protein; 11 types Heat stable (boiling for 30 min) Cause a food poisoning characterized by severe vomiting and diarrhea Staphylococcus(4) Toxic shock syndrome toxin-1 (TSST-1): Induces multisystsm effects (5) Exfoliative toxin: Cause staphylococcal scalded skin syndrome Staphylo

9、coccus2.Pathogensis1) Purulent infection (1) local infection- skin infection: boil(疖); carbuncle(痈) (thick pus; limited local area) (2) organ infection: pneumonia; meningitis. (3) systemic infection: Septicemia; pyemia Staphylococcus2) Toxin diseases (1) Food poisoning (enterotoxin) (2) TSS(Toxic sh

10、ock syndrome) (3) SSSS(staphylococcal scalded skin syndrome) Staphylococcus III. Immunity Staphylococcus IV. Laboratory diagnosis Staphylococcus specimen: *pus * sputum (low respiratory tract infection) *blood (septic shock, endocarditis) * food/faeces or vomit (food poisoning) * mid-stream urine (p

11、yelonephritis or cystitis) direct smear :gram stain isolation and identification: blood agar coagulose test enterotoxin test Staphylococcus V. Treatment Antibiotic therapy Resistance to antibiotics！ eg: penicllin S. aureus 寄生于健康人体的皮肤和鼻腔等处，引起皮肤疖、毛囊炎等。 但它却能够每年都引起成千上万住院病人的感染，包括严重的、有时甚至是致命的外伤性感染、血源性感染和肺

12、炎。 S. aureus 易对已有的抗生素产生耐药性。 Coagulase-negtive staphylococci (CNS)Staph. Epidermidis, Staph. Saprophyticus; Major causes of hospital-acquired infectionTable 7-1. Major properties of three species of staphylococci Main property Staph. aureus Staph. pidermidis S。saprophyticus PigmentationGolden yellow

13、WhiteCitrineCoagulase+- Hemolysin +-Leukocidins+-SPA+-Pathogenicity+-/+- StaphylococcusGram stain of Staphylococcus aureus in pustular exudateStaphylococcus Staphylococcus Section 2. Streptococcus I. Biological characteristics StreptococcusStreptococcusStreptococcus1.Morphology & cultural properties

14、: (1).G+ cocci, arranged in chains, capsule (2).High nutritive requirement (blood & serum) blood agar:* tiny colony ( 0.50.7 mm) *hemolyze erythrocytes in vitro in varying degrees Streptococcus 2.Classification: It is classified based on the hemolyzation phenomenon and antigenic structure. (1).Hemol

15、ytic activity: (i) -hemolytic streptococcus(streptococcus viridans) *Incomplete hemolysis, green coloration of the medium surrounding the colony. *Opportunistic pathogens (ii) -hemolytic streptococcus (or pyogenic streptococcus) Complete hemolysis, major human pathogens (iii) -streptococcus No hemol

16、ysis, no pathogenicity on most cases.Streptococcus -hemolytic -hemolytic -streptococcusstreptococcus streptococcus (2).Antigenic structure: (i) Polysaccharide antigen (group-specific antigen). 20 groups Group A streptococci are main human pathogens (ii) Protein antigen (type-specific antigen). M pro

17、tein: *presents in cell wall (group A) *Anti-phagocytosis *adhere to epithelial cells StreptococcusStreptococcus 3.Resistance *heat labile: 60,30 min *antibiotics sensitivity: penicillin G ,etc. II. Pathogenicity Streptococcus1. Pathogenic substances (1).Invasiveness (i) Adhesin *LTA(lipoteichoic ac

18、id): adhere to sensitive cell * M-protein : anti-phagocytotic II hypersensitivity, III hypersensitivity (ii).Enzyme (spreading factor) * Hyaluronidase * Streptokinase (SK ) * Streptodornase (SD) Streptococcus (2).Toxins-exotoxin(i)Streptolysin (hemolysin) Streptolysin O (SLO) Streptolysin S(SLS) * o

19、xygen-labile oxygen stable O2 (-SH -S-S-) * antigenicity-ASO weak antigen (antistreptolysin O) * protein polypeptide Streptococcus (ii) Pyrogenic exotoxin (Erythrogenic toxin /scarlet fever toxin) *produced by most strains of group A streptococci *cause scarlet fever *possess antigenicity, antitoxin

20、 specifically neutralize the toxin StreptococcusStreptococcus2. Diseases of streptococcal infection 1). Infections of group A -hemolytic streptococci (1). Purulent infections: *pharyngitis *lymphangitis *puerperal fever * tympanitis (2). Toxin-mediated infection : *scarlet fevernecrotizing fascitisS

21、treptococcus(3). Hypersensitive disease (i) Acute glomerulonephritis (ii) Rheumatic feverStreptococcusStreptococcus V. Laboratory diagnosis 1. Isolation & identification of pathogen 2. ASO test: ASO titer 1: 400 units, help to diagnose rheumatic fever. StreptococcusStreptococcusVI. Prevention & trea

22、tment*Treat the pharyngitis and tonsillitis in time, avoid streptococcal hypersensitive disease.*Antibiotics and chemical agents: penicillin G for the first choiceStreptococcusSection 3. Pneumococcus Pneumococcus1. Belong to the Streptococcus ( Streptococcus pneumoniae )2. G+, diplococcus, lancet sh

23、ape,capsule3.Blood agar4.Small colony, - haemolysis, smooth colony (virulent strain) draughtsmancolony(incubation over 24 hour)Pneumococcus5. Pathogenic factor: capsule( antiphagocytosis)6.Disease: pneumonia; tympanitis; meningitis, septicemiaPneumococcus7.Prevent and treatment: capsule polysacchrid

24、e vaccine: 23 types sensitive to a wide range of antimicrobial agent Penicillin, vancomycin Pneumococcus Infections of -hemolytic streptococci (streptococci viridans): normal flora : throat/nasopharynx disease: dental caries SBE (subacute bacterial endocarditis) Streptococcus Section 4 Neisseria Nei

25、sseriaSome are normal inhabitants in respiratory tract. Others are human pathogens eg: gonococcus,meningococcus Common biological characteristics1.Gram negative cocci, kidney-shaped, in pairs have capsules and pili 2.Need enriched medium (chocolate blood agar )3. 510%CO24.Resistance: very weak “frag

26、ile”, extremely sensitive to drying, heat, cold.NeisseriaNeisseria meningitidis Neisseria meningitidispathogenicityNeisseria meningitidis1.Pathogenicity:(1)Human is the only natural host for pathogenic meningococci. Child: susceptible (lacking specific Abs)(2) Pathogenic factor: *pili attach to naso

27、pharyngeal mucosa *capsule antiphagocytosis *LOS main pathogenic substance Neisseria meningitidis2.Pathogenesis: epidemic cerebrospinal meningitis Neisseria meningitidisClinical cause: 3 stages(1)Organisms nasopharynx ( nasopharyngeal infection : asymptomatic , most are carriers, only 23% go to next stage )(2) blood stream (fever, skin ecchymosis )(3) cross the brain barrier (severe headache ,vomitting, stiff neck) meninges (meninges pyogenic inflammation. spinal fluid contain cocci ) Neisseria meningitidisLaboratory diagnosis1. Specimen: spinal f