医学微生物学英文教学课件：7 cocci2

1、BacteriologyShandong University Medical School Department of Medical Microbiology Wei Tang Content1. biological characteristics 2. Pathogenicity & immunity3. microbiological examination4. prevention & treatmentpathogenic factor & pathogenesisdisease Chapter 13Cocci Staphylococcus Streptococcus Pneum

2、ococcus Meningococcus Gonococcus pyogeniccoccusPathogenic coccusG+ cocciG- cocciSection 1. Staphylococcus 1. Staphylococcus aureus (S. aureus) I Biological Characteristics1). Morphology: G+ , arranged in irregular, grape-like clusters no flagellum, no spore capsule in vivo I Biological Characteristi

3、csGram stain of S. aureus in pustular exudate2). Culture temperature : 1840 (37); pH : 4.59.8 (7.4) blood agar - haemolysis Colony : 12 mm, circular, smooth, opaque, pigment - golden yellow I Biological CharacteristicsS.aureusS.epidermidis3). Important Antigens:SPA (staphylococcal protein A)i) cell

4、wall protein surface antigen ii) it combines nonspecifically with the Fc-portion of human IgG iii) anti-phagocytosis iv) damage platelet; cause hypersensitivity; promote cell division; v) coagglutination I Biological CharacteristicsII Pathogenicity & Immunity II Pathogenicity & Immunity 1. Pathogeni

5、c Factors1). Invasiveness (1) Surface structures SPA capsule peptidoglycan teichoic acid II Pathogenicity & Immunity Adherence & anti-phagocytosis (2) Invasive Enzyme Coagulase II Pathogenicity & Immunity 1) free coagulase an extracellular enzyme which is activated by coagulase-reacting factor (CRF)

6、 normally present in plasma, causing the plasma to clot by the conversion of fibrinogen to fibrin. (in tube)II Pathogenicity & Immunity 2) bound coagulase a bound coagulase in the cell wall that induces clumping of cells in the presence of fibrinogen. (in slide)II Pathogenicity & Immunity Coagulase

7、a) to inhibit the phagocytosis of phagocytes and damage of bactericide substances in serum by coating the organisms with fibrin; b) to prevent bacteria spreading - associate closely with pathogenicity of S.aureus II Pathogenicity & Immunity 2). Toxin - exotoxin(1) . Staphylolysin: 、 impairment of me

8、mbrane; cytotoxic effects on phagocytic and tissue cells II Pathogenicity & Immunity (2).Leukocidin: cytotoxic effects on Killing PMN & M(3).Enterotoxin: Heat stable (boiling for 30 min); Cause a food poisoning characterized by severe vomiting and diarrhea;(4). Exfoliatin: Cause blistering of skin (

9、5). Toxic shock syndrome toxin-1 (TSST-1): Induce multisystem effects II Pathogenicity & Immunity 2. diseasesII Pathogenicity & Immunity II Pathogenicity & Immunity 1) Invasive diseases - pyogenic infection (1) local infection: skin infection; folliculitis; boil; carbuncle; impetigo (thick pus; limi

10、ted local area) (2) organ infection: pneumonia; meningitis; endocarditis (3) Systemic infection: septicemia; pyemia2) toxin diseases- exotoxin (1) Food poisoning (enterotoxin) (2) SSSS (staphylococcal scalded skin syndrome) (3) TSS (Toxic shock syndrome)II Pathogenicity & Immunity III Microbiologic

11、Examination specimen: * pus * sputum (low respiratory tract infection) * blood (septic shock, endocarditis) * food/faeces or vomit (food poisoning) * mid-stream urine (pyelonephritis or cystitis) direct smear: gram stain isolation and identification: blood agar coagulase test enterotoxin test PCR te

12、stIII Microbiologic ExaminationIV Prevention & TreatmentAntibiotic therapy Resistance to penicllin Vancomycin current drug of choiceresistance has been observedIV Prevention & Treatment2. Coagulase-negtive staphylococci (CNS)Major biological properties of common staphylococcitest S. aureus S. epider

13、midis S.saprophyticus Colony PigmentGolden yellowWhiteCitrineCoagulase+- Hemolysin+-SPA+-Pathogenicity+-/+-Section 2. Streptococcus1. Structure & Classification of streptococci1) structureC polysaccharide antigen: group-specificM protein It is classified based on the hemolyzation phenomenon and anti

14、genic structure.2) classification (1) hemolyzation phenomenon (i) -hemolytic streptococcus (S.viridans) * Incomplete hemolysis, green coloration of the medium surrounding the colony; * Opportunistic pathogen (ii) -hemolytic streptococcus (S. hemolyticus) Complete hemolysis, major human pathogens (ii

15、i) -streptococcus (S. non-hemolyticus) No hemolysis, no pathogenicity on most cases.2) classification -hemolytic -hemolytic -streptococcusstreptococcus streptococcus (2).Antigenic structure (i) C polysaccharide antigen (group-specific antigen) Group A streptococci are main human pathogens; complete

16、hemolysis (ii) protein antigen (type-specific antigen) M protein 2) classification2. Streptococcus pyogenes (group A streptococcus) I Biological Characteristics1.Morphology & Cultural Properties: (1). G+, arranged in chains, no flagellum, no spore; capsule of hyaluronic acid in the early period. (2)

17、. high nutritive requirement (blood & serum) blood agar: * tiny colony * Complete hemolysis, transparent hemolytic ring I Biological CharacteristicsII Pathogenicity & Immunity II Pathogenicity1. Pathogenic factors (1).Invasiveness (i) adhesin * LTA (lipoteichoic acid): adhere to sensitive cell (epit

18、helial cell、mucous membranes) * M-protein anti-phagocytosis M-Ag Ab hypersensitivity (glomerulonephritis) Common antigen- cross-reacts heart myosin (autoimmunity - rheumatic fever) II Pathogenicity (ii) Invasive enzymes (spreading factor) * Hyaluronidase Splits hyaluronic acid bacteria spread * Stre

19、ptokinase (SK ) Lyse fibrin, prevent plasma clotting bacteria spread * Streptodornase (SD) Resolve DNA bacteria spreadII Pathogenicity (2) Toxin - exotoxin i) Streptolysin (hemolysin) Streptolysin O (SLO) Streptolysin S(SLS) * oxygen-labile oxygen stable (-SH -S-S-) * protein polypeptide * antigenic

20、ity - ASO weak antigen (antistreptolysin O) * destroy WBC, platelet destroy WBC virulence of many tissues II Pathogenicity (ii) pyrogenic exotoxin (erythrogenic toxin /scarlet fever toxin) * most virulent substance * cause scarlet fever II PathogenicityII Pathogenicity2. Diseases (1) Pyogenic Infect

21、ions: * tonsillitis *pharyngitis *lymphangitis *necrotizing fascitis *puerperal fever (2) Toxin-mediated Infection : *scarlet feverII Pathogenicity (i) Rheumatic fever *common Ag cross-reacts heart type II hypersensitivity *immune complex (deposition) heart, joints type III hypersensitivity II Patho

22、genicity(3) hypersensitive disease (ii) acute glomerulonephritis ( group A) * type III hypersensitivity (most) * type II hypersensitivity M protein-Ab common Ag Immune complex Ab deposition glomerular basement membrane cross reacts with glomerular basement membrane activationC3,C5 tissue destruction

23、 tissue destruction II PathogenicityIII Microbiologic Examination 1. Isolation & identification of pathogen 2. ASO test: ASO titer 1: 400 units, help to diagnose rheumatic fever. III Microbiologic ExaminationIV Prevention & Treatment*Treat the pharyngitis and tonsillitis in time, avoid streptococcal

24、 hypersensitive disease.* Antibiotics and chemical agents: penicillin G for the first choiceIV Prevention & Treatment3. Streptococcus pneumoniae (pneumococcus) 1. G+, lancet-shaped cocci arranged in pairs (diplococcus), capsule2.Blood agar, -hemolysis, smooth colony (virulent strain)3. autolysis (in

25、cubation over 48h) I Biological Characteristics1. Pathogenic factor capsule (anti-phagocytosis) (SR); pneumolysin2.Disease lobar pneumonia, bronchitis, tympanitis, meningitis, septicemia II PathogenicityIII Microbiologic Examination1. specimen sputum, pus, blood, cerebrospinal fluid (CSF) 2. direct

26、smear gram stain3. isolation and identification blood agar, -hemolysis distinguished from -streptococcus 1. Prevention polyvalent capsule polysacchride vaccine2. Treatment penicillin G, erythromycin, vancomycin IV Prevention & Treatment4. Other streptococcus related to medicineviridans streptococci

27、(-hemolysis)1. normal flora : mouth, throat/nasopharynx2. *S.mutant- dental caris *S.anginosus- (subacute bacterial endocarditis, SBE) damaged heart valve, fever, heart murmur , enlarged spleen, anemiaSection 3. NeisseriaG- cocci, usually arranged in pairs. most are normal floras in nose, pharynx an

28、d mouth mucosa. Gonococcus and meningococcus are human pathogens 1. Neisseria gonorrhoeae (gonococcus)1. G- diplococcus, kidney-shaped, capsules and pili 2. obligate aerobe 3. need enriched medium (chocolate blood agar )4. resistance very weak “fragile”, extremely sensitive to dry, heat, cold, commo

29、n disinfectants I Biological Characteristics I Biological Characteristics5. Surface antigen * Pili * Outer membrane protein * LOS 1. Pathogenic factor * Pili attach to epithelial cells (urinary-genital tract) * Outer membrane protein adherence * LOS like LPS, endotoxin activity II Pathogenicity2. Di

30、seasesHuman is the only natural host *Gonorrhea (sexually transmitted disease, STD) acute urethritis (male); pelvic inflammatory (female)*ophthalmia neonatorumblindness II PathogenicitySpecimen purulent secretion of genitourinary tract Isolation and identification direct smear, culture, biochemical tests III Microbiologic Examination *no vaccine *peni