lecture 6 Flashcards
what are commensals? Q. Our microbiota are often called commensals. How accurate is that term?
the host (e.g. human, plant, fungi) receives no benefit or harm, the microbe benefits from the interaction
Human commensal bacteria include the microbiota (flora) of the skin, respiratory tract and gut
E.g. Staphylococcus epidermidis grows on the surface on skin, feeds on sebum secretions, no negative effect for host
E.g. gut bacteria - human large bowel provides warm, moist, protected environment for microbes, no negative effect on host
The commensal interaction can change to a parasitic interaction if the environment changes, e.g.:
Staphylococcus aureus can invade the body through broken skin
Use of antibiotics upsets the balance of microbes in the gut, can result in diarrhoea. cos they kill both gram negative and gram positive. spores wont be usually effected by the antibiotics such as yeast fungi. so you can get the yeast overgrowing in the bowel after a treatment
what word do you use when talking about biofilms?
surface
Q. Which of the following help create an environment leading to dental carries?
aerobes
facultative
anaerobes
anaerobes
anaerobic - streptococci make biofilms, stick to the teeth and eat your sugar. they make acid when the grow and cause tooth decay.
what is parasitism? Q. How could contact lens saline grow Pseudomonas?
The parasite grows as the expense of the host, causing damage while obtaining nutrients and a favourable environment
Parasites are also referred to as pathogens (patho - diseases, gen - generate)
The result of the host-parasite relationship depends on the pathogenicity of the parasite
The resistance/susceptibility of the host also varies
Opportunistic pathogens only cause disease in the absence of normal host resistance or when an opportunity exists
E.g.: Pseudomonas aeruginosa – loves moisture, also attaches well to plastic
explain parasites and disease
the pathogenicity of a parasite is measured by its virulence
Host-parasite relationships are dynamic, with the virulence of the parasite and the resistance of the host constantly changing
Infection – where a microorganism is growing in a host, with or without host damage
Disease – damage that impairs host function
Host organisms (animals, plants, microbes) have a variety of defence mechanisms that prevent/inhibit microbial growth
The parasites must invade (not always invading tho) microbial barriers, such as skin, mucous membranes and intestinal epithelium or produce toxins
how does disease transmit?
Contact transmission
- Direct contact transmission
- Indirect contact transmission
- Droplet transmission
- Vehicle transmission (water, food, airborne)
- Vectors
- Arthropods (insects)
- Mechanical transmission
- Biological transmission
round bacteria seen at 1000x magnification are called coli cocci coxsi coccyx
gram positive cocci in clusters resembling staph
rod shaped organisms on gram stain can be called
bacilli
staphylococcus
bacillis
streptococcus
bacillis - is a name for a group of bacteria. its bacilli
looking more closely at the last smear we can see
flagella
cell wall
capsule
spore
spore
when transferring bacteria from a growing broth to fresh broth you use
streak dilution
the gram stain
asceptic technique
the microscope
asceptic technique
the following best describe the microscopy of the image shown
gram positive cocci
gram negative rods
staph and e coli.
gramp positive rods and gram negative rods (opposite)
staph and e coli
the best term to describe what is seen in the image is
viral plaques
cooci
colonies
bacilli
viral plaques
heat fixation on smears is to
gram stain slides
attach organisms
kill organisms
dry slides
attach organisms
