16. Infectious Diseases Flashcards
Define ‘pathogenic’
Disease-causing microbes
Explain the relation and give an example of a commensal microbial relationship
Commensal = symbiotic relationship whereby the microbe benefits and the host is unaffected
E.g. Microbes on your skin
Explain the relation and give an example of a mutualistic microbial relationship
Mutualistic = a symbiotic relationship whereby both the microbe and the host benefit.
E.g. E. coli which makes vitamin K for humans
Explain the relation and give an example of a parasitic microbial relationship
Parasitic = a symbiotic relationship whereby one organism benefits at the other’s expense.
E.g. head lice
Explain the relation and give an example of a opportunistic microbial relationship
Opportunistic = symbiotic relationship between organisms that is initially commensal/mutualistic but becomes parasitic
E.g. candida
Describe the difference between Pasteur and Bechamp’s microbe theories
Pasteur presented ‘germ theory’ of disease saying that all germs are bad and cause disease.
Bechamps developed terrain theory whereby germs are opportunistic in nature and live with us symbiotically. To prevent illness we should not kill germs but promote health.
List two differences between ‘gram negative’ and gram positive’ bacteria
Gram positive:
1) thick cell wall
2) stains purple with Gram’s method
Gram negative:
1) thinner cell walls
2) stains pink with Gram’s method
Discuss this statement:
‘Bacteria are prokaryotic cells with a simple structure, nucleus and membrane bound organelles’
Although it is correct that they are prokaryotic and simple structures, they no not have nucleus or membrane bound organelles.
Describe TWO key differences between ‘exotoxins’ and ‘endotoxins’.
Exotoxins:
1) very toxic
2) released by living microbes
Endotoxins:
1) less toxic
2) released from cell wall after organisms death
Name ONE method by which bacteria reproduce.
Binary fission
With regards to resident and transient microflora, list:
a. TWO body locations where microflora is present
b. TWO body locations where microflora is absent
a. microflora present:
- small & large intestine
- mouth
- skin
- vagina
- nasal cavity
b. microflora absent
- blood
- cerebrospinal fluid
- lungs
- stomach
- uterus
- bladder
- kidneys
Describe how microflora organisms can become pathogenic.
Can become pathogenic if the local environment changes or if immune system becomes compromised (opportunistic)
Explain how broad-spectrum antibiotics affect microflora in the body.
They possess no specificity for bacteria they kills and instead can have devastating effects on the body’s microflora
List TWO adverse effects of broad-spectrum antibiotics.
- Impaired immunity
- candida overgrowth
- diarrhoea
Describe the structure of a virus.
Incredibly basic organism.
Strand of RNA or DNA in a hard protein coat (capsid)
Name TWO DNA viral pathologies.
- coldsores
- chicken pox
- Shingles
- small pox
Name TWO RNS viral pathologies.
- Measles
- Mumps
- HIV
Describe how viruses reproduce.
By injecting their RNA/DNA strands into a living host cell and use the host cell’s apparatus for reproduction
Describe FOUR ways in which viruses make it difficult for the body to identify and destroy.
1) Hide inside a host cell
2) Don’t have a metabolism of their own
3) Have few structures of their own
4) Able to mutate
Explain the term Viral lysis
Virus particles burst out of the host cell into the extracellular space causing cell death of host
Explain the term Viral budding
Virus exits a call and acquires an envelope (outer membrane) of its own from the host cell. Host cell dies in process.
Explain the term Latent stage
Stage where the disease is present but hidden or inactive
Describe how the following promote fungal growth in the body:
a. Yeasts
b. Dermatophytes
Yeast = reproduce through budding
Dermatophytes = obtain nutrients from keratin in the skin
List FOUR factors that promote growth of fungi in the body.
- Warmth
- Moisture
- Nutrients
- Acidity
List TWO ways in which fungi reproduce.
- Asexual via budding
- Sexual through fungal spores
Name ONE example of a protozoa
MAlaria
What’s a helminth?
A parasitic worm
Define the following terms:
a. Epidemic
b. Pandemic
c. Endemic
a. Epidemic = infection occurring in large groups
b. Pandemic = infection is worldwide
c. Endemic = infection is restricted to an area
What is the term used to describe:
Location the pathogen exists, reproduces and spreads to new hosts
Reservoir
With regards to infection sources, define ‘carrier’
Infected individuals who are asymptomatic
With regards to infection sources, define ‘vector’
Intermediate carrier transporting pathogens from reservoir to host
What is the term used to describe an infected person or animal
Host
Explain what is meant by ‘nosocomial’.
Infection is acquired from a medical setting
Describe in detail the FOUR stages of infection.
1) Incubation period - time between initial exposure and appearance of first signs/symptoms
2) Prodromal period - early, non-specific symptoms are displayed (malaise, fever, etc)
3) Acute-period - Pathogens peak in population. Very pronounced symptoms specific to disease
4) Chronic infection - infection with insidious or slow offset of long duration
List FOUR ways in which a host can provide resistance against microbes
- Intact skin and mucous membrane
- Body secretions (stomach acid, tears etc)
- Phagocytosis
- Interferon production
- Effective inflammatory response
- Effective immune system
List FOUR ways in which a microbe displays ‘virulence’ against a host.
- Productive of invasive/destructive enzymes
- Production of endo- or exo-toxins
- Spore formation
- Entry of a large number of organisms (colonies)
- Presence of bacterial capsules or pili
- Ability to mutate
State THREE methods to reduce the spread of infection.
- Stop droplet transmission (covering the mouth, not with hand)
- Block method of transmission (hand washing, gloves, condoms)
- Kill the organism
- Sterilisation
Explain how the following ‘infection control’ processes work:
a. Sterilisation
b. Pasteurisation
Sterilisation = all micro-organism and their spores are destroyed by prolonged heat.
Pasteurisation = Most pathogenic microbes are killed but not their spores by a short exposure to heat
With regards to natural anti-microbials, name TWO examples for Anti-bacteria
- Garlic
- Oregano
- Grapefruit seed extract
- Tea tree
- Thyme
- Collodial silver
With regards to natural anti-microbials, name TWO examples for Anti-fungal
- Garlic
- Oregano
- Cinnamon
- Berberine
With regards to natural anti-microbials, name TWO examples for Anti-viral
- Elderberry
- Olive lead
- St John’s Wort
- Lemon balm
With regards to natural anti-microbials, name TWO examples for Anti-parasitic
- Garlic
- Black walnut
- Wormwood
- Berberine
- Goldenseal
- Oregano