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Flashcards

Bacterial Pathogenicity

Florence Edwards Animal Disease 1 English 36 cards

Cards in this deck (36)

  1. 1What is the term for free-living bacteria?Saprophytes
  2. 2Why will free-living bacteria not cause disease?Not adapted to live in host e.g. incorrect temperature optima
  3. 3What is the term for bacteria that live in/on a host and spread between animalsParasitic bacteria
  4. 4What is a symbiotic relationship?Bacteria and host gain
  5. 5Give an example of a symbiotic relationshipCellulose digestion in the rumen by cellulase producing bacteria
    Bacteria obtain nutrients and more energy available to host
  6. 6What are commensal relationships?Bacteria gain but cause no harm
  7. 7What are commensal bacteria specific to?Host
    Site
  8. 8When can commensal bacteria become harmful?Some commensal bacteria can become facultative pathogens
    For example, E.Coli is commensal in the gut but pathogenic if it enters the abdominal cavity (e.g. during gut surgery)
  9. 9What are pathogenic bacteria?Gain by causing harm to the host
  10. 10What are the 2 types of pathogenic bacteria?Obligate pathogenic
    Facultative pathogenic
  11. 11What 2 types of bacteria can become facultative pathogenic?Saprophytes
    Commensals
  12. 12What causes bacteria to become facultative pathogenic?Altered host conditions
  13. 13What is exogenous infection?Infection from environment or other hosts
  14. 14What is endogenous infection?Infection results from animal's own commensal flora
  15. 15When can staphylococcus aureus become facultative pathogenic?Carried in nose and usually harmless (commensal)
    Can cause abscesses if introduced through the skin or septicaemia if introduced into the blood system
  16. 16When can antibiotics cause commensal flora to become pathogenic?Clostridium difficile is antibiotic resistant so will proliferate in antibiotic therapy = antibiotic induced colitis in horses and humans
  17. 17When can rapid nutritional change lead to commensal bacteria becoming facultative pathogenic?Proliferation of Clostridium perfringens = acute enterotoxaemias
  18. 18Give 5 ways in which defences may be reduced causing an increase in facultative pathogenicityExtremes of age
    Malnutrition
    Immunosuppressive drugs (e.g. corticosteroids suppress T cell proliferation)
    Primary infection
    Stress
  19. 19Describe the pathway of shipping fever in transported calvesStress caused corticosteroid release
    Inhibition of immune defence
    Primary respiratory virus e.g. parainfluenza
    Damaged alveolar macrophages
    Susceptible to secondary bacterial infections e.g. Mannheimia haemolytica commensal
    Pneumonia
  20. 20How do alveolar macrophages reduce likelihood of facultative pathogenicity?Keep population of commensal bacteria under control
  21. 21What is bacterial pathogenicity?Ability of a bacterial species to cause disease e.g. Salmonella species is pathogenic
  22. 22What is virulence?Degree of pathogenicity associated with a particular bacterial strain
  23. 23What are virulence determinants?Structural and/or biochemical features that enable a bacterium to overcome or evade the host defences so it is more virulent
  24. 24What species of bacterium causes strangles in horses?Streptococcus equi
  25. 25What are the 2 types of bacterial invasion?Superficial invasion of skin/ mucous membrane epithelium
    Deeper invasion of blood or lymph vessels (more virulent)
  26. 26What are the 2 ways in which bacteria can invade a host?Digestion of host tissues
    Subversion of host defences
  27. 27Give 4 ways bacteria can avoid complement activationPrevent antibody detection through a capsule or fibrin covering
    Spatial hindrance by lipopolysaccharides which are antigenic so activate MAC
    Preventing MAC development
    Mutation to avoid antibody recognition (existing antibodies against commensals)
  28. 28Which species uses fibrin to prevent detection by host cells?Some species of Staphylococcus convert fibrinogen to fibrin by producing coagulase
    Recognised as host tissues
  29. 29How can fimbriae help bacteria avoid the immune response?Tight adhesion to epithelium
    Prevents macrophage uptake and digestion
  30. 30Give 3 ways in whch chemicals produced by bacteria can help avoid the non-specific immune systemRepel phagocytes or inhibit chemotaxis
    Prevent phagocyte activity
    Kill phagocytes
  31. 31What is the term for chemicals that prevent leukocyte activity?Leukostatins
  32. 32What is the term for chemicals that kill leukocytes?Leukocides
  33. 33Give 5 ways in which bacteria can avoid the specific immune responseBacterial immunosuppression of T and B cells
    Entering host cells by endocytosis
    Inhabiting privileged sites with low immune surveillance
    Antigenic mimicry
    Antigenic variation
  34. 34Give an example of a site of the body with low immune surveillanceJoints
  35. 35Give an example of antigenic mimicryLipopolysaccharides in gram positive bacteria can mimic host sugars
  36. 36What is the term for bacterial spread to new hosts?Transmission

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Animal Disease 1 (Agents of Disease) Flashcards on Bacterial Pathogenicity, created by Florence Edwards on 26/11/2016.
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