microbiology midterm #2 Flashcards
what are the types of microbial control?
-sterilization
-disinfection
-sanitization
-antisepsis
-degerming
-asepsis
-biocide/germicide
-bacteriostasis
what is sterilization?
removal or destruction of ALL MOs
(ex cleaning surgical equipment)
what is disinfection?
treatment that kills or inhibits the growth of harmful MOs
(ex. cleaning a hospital room in between patients)
what is sanitization?
reduction of MOs to minimize transmission
(ex. food preparation areas or equipment)
what is antisepesis?
disinfection of live biological sample such as the skin or mucous membrane
(ex. showering before surgery)
what is degerming?
antisepsis that is localized into a small region of the body
(ex. cleaning the skin before a vaccination)
what is asepsis?
complete absense of bacterial contamination
what is biocide/germicide?
treatment that kills living MOs
what is bacteriostasis?
treatment that only halts or prevents growth of the bacteria (no bacteria death occurs)
what are the factors that influence microbial control?
-the death rate of the MO( MOs do not die immediately)
-alteration of rate (rate can be altered by environment, time the MO is exposed to treatment, and nature of the MO)
what are the three things a control agent can effect in the MO?
-plasma membrane
-proteins
-nucleic acids
how does a control agent effect the plasma membrane in an MO?
destruction of the plasma membranes permeability hampers the growth of the cell
how does a control agent effect the proteins in a MO?
control agent alters the shape of the protein via heat or chemicals to effect the cells function (denaturization)
how does a control agent effect the nucleic acids in a MO?
the control agents interfere with the bonds between atoms causing the prevention of proper protein function and formation
what are the 4 physical methods of MO control?
-heat
-filtration
-dessication
-radiation
how does heat control MOs?
heat denaturizes the proteins( alters the shape)
-moist heat and dry heat
how does filtration control MOs?
Physically seperates the MOs out of a smaple based on size (liquid or gas)
how does dessication control MOs?
removes the water from the MO that it needs for survival
what are the two types of radiation?
ionizing (xrays, gamma rays, electron beams)
non-ionizing (ultraviolet/UV)
how does ionizing radiation work?
-mutation of DNA
-sterilizes food, pharmaceuticals, and disposal of medical implements
-greater penetrating power
how does non-ionizing radiation work?
-mutation of DNA
-room sterilization (UVlamps)
-less penetrating power (only affects the skin)
what are the 5 modes of action?
1.inhibition of cell wall synthesis
2. inhibition of protein synthesis
3. inhibition of nucleic acid replication and transcription
4. injury to plasma membrane
5. inhibition of essential metabolite synthesis
what happens in the first mode of action?what kind of antibiotics are used?
inhibition of cell wall inhibition: without the cell wall the cell is not protected from environment and the osmotic pressure causes lysis
-penicillin
what happens in the second mode of action and what kind of antibiotics are used?
inhibition of protein synthesis: antibiotics alter the shape of the proteins
-streptomycin
-chloramphenical
-tetracycline
-erythromycin
what happens in the third mode of action and the antibiotics used?
inhibition of the plasma membrane: antibiotics alter the permeability of the membrane allowing essential nutrients out.
-amphotericin B
-Ketoconazole
what happens in the fourth mode of action and what antibiotics are used?
inhibition of nucleic acid synthesis: prevents the MO from reproducing and growing
-could cause side effects by effecting the hosts DNA/RNA
-quinolones (ciprofloxacin)
what is the fifth mode of action and what are the antibiotics used?
inhibit the synthesis of essential metabolites: prevent synthesis by competing for an enzyme in a metabolic pathway
-sulfonamides
what are the five mechanisms of drug resistance?
- blocking entry
- inactivation by enzymes
- alteration of target molecules
- efflux of antibiotics
how does the first mechanism of drug resistance work and what is an example of a resistance?
prevention of entry: the Mo has some sort of protective structure preventing the antibiotic from reaching its target molecule
-gram-negative bacteria
how does the second mechanism of drug resistance work and what is an example of a resistance?
inactivation of enzymes: The MO produces an enzyme that destroys or deactivates the antibiotic
-penicillin resistance
how does the third mechanism of drug resistance work and what is an example of a resistance?
alteration of target molecule:change in shape of the effected protein or structure prevents the antibiotic from reaching its target molecule
-staphylococcus aureus
how does the fourth mechanism of drug resistance work and an example of a resistance?
efflux of antibiotic: MO expels antibiotic from the cell so it can’t bind
-can occur with all types of antibiotics
how do you properly use antibiotics?
-take antibiotics as prescribed
-do not skip doses
-do not save antibiotics
-do not take antibiotics prescribed for someone else
-all drugs have side effects
what kind of bacteria causes tuberculosis?
mycobacterium tuberculosis
what is pathogenicity?
the ability of an MO to overcome a hosts defences and cause a disease
what is virulence?
a measure of pathogenicity of an MO, the higher the virulence the higher the ability to cause disease
what are the 3 major portals of entry?
-mucous membrane
-skin
-parenteral route
explain the mucous membrane portal of entry?
-respiratory: MO enter by being breathed in
-gastrointestinal: MOs that are ingested
-genitourinary tract: STIs
what are the most common MOs that spread via respiratory tract?
-influenza
-bordetella pertuttis (whooping cough)
-streptococcus pneumoniae
-mycobacterium tuberculosis
what are the most common MOs that are spread via gastrointestinal tract?
-shigella spp.
-salmonella enterica
-S.typhi