Week 11 - Pathology Of Infections Flashcards
Why do infectious diseases differ and give examples?
- some organisms are capable of living in any tissue
- some organisms are capable of releasing products that damage widely
- some organisms are capable of living or reproducing in very few tissues
- some organisms release products that damage only certain tissues
How do bacteria damage tissue?
-pili on the surface attach to cell walls, allowing adhesion
-exotoxins
-endotoxins
-agressins
-immune reactions
-immune cross-reactions
-cell-mediated immunity
-
What are exotoxins produced by and what do they do?
- produced by intact bacteria
- typically have specific effects
What are endotoxins produced by and what do they do?
- components of cell walls
- trigger complement cascade
- trigger coagulation cascade
- induce interleukin 1, causing fever
What are agressins produced by and what do they do? (Give examples)
-produced by bacteria
- coagulase - staph aureus
- streptokinase - strep pyogenes
- collagenases - various
How do immune reactions from bacteria damage tissue?
-antibody-antigen complexes deposited in glomerulus or skin –> glomerulonephritis and cutaneous vasculitis
Give an example of how immune cross-reactions from bacteria damage tissue
-e.g. Streptococcal sore throat leading to rheumatic fever
How to viruses damage tissue? (Give examples)
- direct cytopathic effects (influenza virus, hep A)
- immune reactions (hep b and c, diabetes - type 1)
- incorporation of viral genes into host genome (variety of oncogenic viruses)
Name a fungal infection and how it may occur/affect in the body in different ways
Aspergillus spp
- few cases of asthma - airway colonisation
- aspergilloma - fungal ball in pre-existing cavity
- invasive aspergillosis - immunosuppression
- hepatocellular carcinoma - aflatoxins from A flavus
Name a yeast infection and how it may occur/affect in the body in different ways
Candida albicans (thrush)
Local - oral/vaginal, poor hygiene, bacterial flora alterations, diabetes mellitus
Systemic - immunosuppressed
Name some parasites
Protozoa
Trematodes (flukes)
Nematodes (round worms)
Cestodes (flatworm or tapeworms)
What are Protozoa and what diseases do they cause?
Parasite
- amoebiasis - (entamoeba histolytica), colon colonisation causing amoebic dysentery, amoebic abscesses eg liver
- giardiasis - (giardia lamblia, small intestinal infection, diarrhoea and weight loss
- malaria - (falciparum spp), mosquitoes spread, colonise RBC, can obstruct cerebral capillaries
- trichomoniasis - (trichomonas vaginalis), venereal (sexually) transmission
What are flukes (trematodes) and what diseases do they cause?
Parasite
- schistosomiasis (schistosoma spp - flukes), life cycle involves humans and water snails
- granulomata - in bladder (S haematobium) or in liver (S mansoni/japonicum)
What are flukes (trematodes) and what diseases do they cause?
Parasites
- round worms - (enterobius vermicularis - thread worms)
- tape worms - (diphyllobothrium latum) - fish tapeworm causing vit b12 deficiency, (echinococcus granulosus) - dog tapeworm causing liver cysts
What are prions?
Infectious particles with no DNA or RNA
What can prions cause?
- transmissible spongiform encephalopathy
- Creutzfeldt-Jakob disease
- exogenous protein causes conformational changes in endogenous protein
Which organ is more commonly exposed to bacteria than any other?
The lungs
What are the classes of infectious agents?
Bacteria Viruses Fungi - including yeasts Parasites Prions
