Infectious Diseases Flashcards
4 types of micro organism
Bacteria
Viruses
Fungi
Protozoa
What are non-pathogenic microorganisms?
Non-disease causing
Can be symbiotic but can become pathogenic
10 x as many bacterial cells as human cells in body
What is a commensal microbe relationship
Symbiotic relationship where one benefits and the other is unaffected e.g. microbes in your skin
What is a mutualistic microbe relationship
Symbiotic relationship where both benefit - e.g. E. coli make vitamin K for humans
What is a parasitic microbe relationship?
Sybiotic relationship where one benefits at the other’s expense e.g. head lice
What is an opportunistic microbe relationship?
A symbiotic relationship which is initially commensal/mutualistic then becomes parasitic e.g. candida
Brief history of microbes
Pasteur - germ theory - germs cause disease and developed pasturisation
Bechamp - germs are opportunistic and live with us symbiotically
Terrain theory - not to kill germs but promote health
How are microbes identified
Cultured (grown) in labs
Views under a light or electron microscope
What type of cells are bacteria
Prokaryotic
Simple with no nucleus
What is the control centre of bacteria
A single loup of DNA
What are the two types of bacteria
Gram positive - thick mech-like cell wall - stain purple
Gram negative - thinner cell wall - stain pink
How do bacteria reproduce
Binary fission
Spore formation
Compare exotoxins and endotoxins
Exotoxins - gram positive and negative
released by living microbe
Endotoxins
gram-negative only
Released after organism death from cell wall
Where do you find microflora
Nasal cavity
Skin
Mouth
Small and large intestine
Vagina
Perineum
Where is microflora absent
Blood
cerebrospinal fluid
lungs
stomach
Uterus
fallopian tubes
ovaries
bladder kindneys
What do antibiotics do?
Destroy bacteria
What are viruses?
obligate intracellular parasites - needing a host to survive and replicate
2 types of virus and examples
DNA virus - herpes, smallpox
RNA virus - measles, mumps, HIV
How do viruses reproduce?
By injecting their RNA or DNA into a living host cell to use it for reproduction
What remains outside a host cell when a virus binds to a cell?
It’s capsid coating
4 reasons viruses are more difficult to identify
- Hide inside a host cell and can be latent
- They do not have a metabolism of thier own
- Do not have many structures of their own
- They are able to mutate
3 ways viruses can replicate?
Viral lysis
Viral budding
Latent stage
how does viral lysis work?
Virus particules burst out of host cell - death of host cell
How does viral budding work?
Virus exits the cell and aquires an envelope
Usually leads to cell death
How does latent stage work?
Disease is present but hidden
What type of organisms are fungi?
Eukaryotic
Can be single-celled or very complex
What are fungi filaments called?
Hyphae
What is a mass of fungi
Mycelium
3 types of fungi
Yeasts
Moulds
DErmatophytes - fungi causing skin disease
How to fungi grow?
Hyphae
Mycelium - mesh
Environment - warm, moist, rich nutrition, acidic
How do fungi grow
Asexual reproduction - via budding
Sexual reproduction (less common) via fungal spores
What type of organism are protozoa?
Eukaryotic
No cell wall, just membrane
Moist environments
How do protozoa reproduce?
Binary fission and budding
Sexual reporduction
What are helminths
Parasitic worms
Eukaryotic
What is an endemic
Infection restricted to an area
What is a reservoir
Location where patogen exists, reproduce and spreads to new hosts
What is a carrier
Infected individuals who are asymptomatic
What is a vector
Intermediate carrier, transporting pathogens
What is a host
Infected person or animal
5 ways infections can be transmitted
droplet
Direct contact
Indirector contact
Vector - carried by an insect or animal
Nosocomial - aquired from a medical setting
What is a nosocomial tramsmission
Infection acquired in a medical setting
6 ways infection can be aquired
Injestion
Blood stream
Sexual intercourse
Inhalation
Touch
Placental
