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Microbio > Microbial Control (6) > Flashcards

Microbial Control (6) Flashcards

1
Q

biocide

A

will kill or inactivate a pathogen/microbe

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2
Q

sterilization

A

killing or inactivating everything
- hard to achieve

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3
Q

sanitization

A

lowering microbial load to “safe” level

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4
Q

disinfectant

A

powerful agent used on inanimate objects

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5
Q

antiseptic

A

used on live beings

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6
Q

-cidal

A
  • killing
  • can have side effects, toxicity
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7
Q

-static

A
  • prevents replication, immune system then steps in
  • may take longer
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8
Q

biosafety levels: BSL-1

A
  • most harmless
  • resident microbiota (inside us) pose no threat
    • L. casei
    • V. fisher
  • handwashing and disinfecting surfaces
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9
Q

biosafety levels: BSL-2

A
  • some pathogens
  • handwash, disinfect, gloves
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10
Q

biosafety levels: BSL-3

A
  • cause disease via consumption, wound entry, inhalation
  • use safety ventilation hood
  • potential ailments are fairly treatable
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11
Q

biosafety levels: BSL-4

A
  • highly dangerous, contagios
    • ebola, variola
  • decontamination chamber, space suit
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12
Q

methods of control: 3 genres

A
  • physical
  • chemical
  • biological agents
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13
Q

physical control: mechanical removal

A
  • filtration
    • heat-sensitive sterilization
    • certain liquids
    • air filtration
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14
Q

physical control: heating

A
  • destroys viruses, fungi, bacteria
    • spores in some conditions
  • degrades nucleic acids, denatures proteins, disrupts membranes
    • extracts water
  • bacteria take 2-800 min @ boil to die
    • 121 °C sterilization is achieved
    • steam sterilization: autoclave (sporocidal, quality control, bioindicatiors)
  • autoclave
    • heat and pressure chamber
    • temp increase, pressure increase
    • steam enters chamber
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15
Q

physical control: pasteurization

A
  • sanitization method
  • controlled heating at specific temps for specific times
  • milk, beer, etc.
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16
Q

vat pasteurization

A

63 °C for 20 minutes

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17
Q

high temperature short time (HTST) pasteurization

A

71.5 °C for 15 seconds

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18
Q

ultra pasteurization

A

135 °C for 2 seconds
- sterile

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19
Q

physical control: dry-heat sterilization

A
  • bacticinerator or oven
  • less effective than moist heat
  • 160-170 °C
  • oxidizes cell structure, denatures proteins
20
Q

physical control: UV radiation

A
  • causes thymine dimers
  • UV use limited
21
Q

chemical control: disinfectants and antiseptics

A
  • effective against wide variety of infectious agents at low temp
  • stable in storage
  • safe for humans and animals
  • overuse = triclosan-resistant bacteria
    • 2016 FDA antimicrobial ban
22
Q

chemical control: phenolics

A
  • Joseph Lister
  • denatures proteins, disrupts cell membranes
    • Lysol (remains active for a while)
23
Q

chemical control: alcohols

A
  • most widely-used
    • denature proteins, dissolve membrane lipids
  • ethanol, isopropanol
  • not effective for all viruses
    • norovirus
24
Q

chemical control: aldehydes

A
  • highly reactive molecules
  • cross-linking proteins (stiffening)
    • formaldehyde
25
Q

chemical control: heavy metals

A
  • mercury, silver, arsenic, zinc, copper
  • effective but toxic, replaced by less toxic alternatives
  • inactivate proteins
  • thiomersal: contains mercury, preserves vaccines
    • was pulled from all childhood vaccines after autism controversy
26
Q

chemical control: sterilizing gases

A
  • microbicidal and sporocidal
  • ethylene oxide sterilization
  • combine w/ and inactivate DNA and proteins
27
Q

biological control: natural methods

A
  1. predation by bdellovibrio
    - toxic secretions kill similar species
  2. bacteriophages
    - viruses that attack bacteria
  3. bacteriocins
    - toxic secretions that kill similar species
  4. fecal transplants
    - reducing microbiota by excess antibiotics
    - healthy microbiota from one individual, inoculating another
    - prebiotics first
28
Q

antimicrobial chemotherapy

A
  • antimicrobial agents treat disease
  • kill or inhibit pathogens
  • used within body
    • antibiotics
29
Q

characteristics of antimicrobial chemotherapy

A
  1. selective toxicity
  2. therapeutic dose
  3. toxic dose
  4. narrow spectrum drugs
  5. broad spectrum drugs
30
Q

selective toxicity

A

kill/inhibit pathogen without damaging host

31
Q

therapeutic dose

A

dose required to treat infection

32
Q

narrow spectrum drugs

A

genera, species
- ideal

33
Q

broad spectrum drugs

A
  • can kill “good” bacteria but can also wipe out multiple pathogens
34
Q

determining level of antimicrobial activity: methods

A

kirby-bauer
- zones of inhibition

35
Q

antibiotics: inhibitors of cell wall synthesis

A

penicillins
- B-lactam ring
- inhibits peptidoglycan synthesis
- penicillinase: cuts C-N bond in ring (resistance to penicillin)
- transpeptidase inhibition (amino acid linking)
- most effective in dividing bacteria
- direct binding to active site
- selective toxicity: only bacteria have peptidoglycan layer

36
Q

antibiotics: protein synthesis inhibitors

A
  • specific to ribosomes
  • tRNA binding, mRNA reading
  • tetracyclines
    • broad spectrum, bacteriostatic
    • inhibits binding of tRNA
37
Q

antibiotics: metabolic antagonists (list types)

A
  1. antimetabolites
  2. sulfonamides or sulfa drugs
38
Q

antimetabolites

A
  • type of metabolic antagonist
  • block metabolic pathways
  • broad spectrum, usually bacteriostatic
39
Q

sulfonamides

A
  • type of metabolic antagonist
  • compete with PABA for binding site
  • selective toxicity: bacteria synthesize folic acid rather than ingest it
40
Q

antibiotics: nucleic acid synthesis inhibitors

A
  • variety of mechanisms
    • DNA and transcription blocking
  • fluoroquinolones
41
Q

fluoroquinolones

A
  • nucleic acid synthesis inhibitor
  • broad spectrum
  • inhibits DNA gyrase (which eases strain) and topoisomerase IV
42
Q

topoisomerase IV

A

breaks hydrogen bonds to form separate chromosomes

43
Q

drug resistance

A
  • major public health issue
  • 70% of antibiotic use = livestock
    • increased animal yield
  • improper prescribing
  • “superbugs”
44
Q

superbugs

A
  • drug-resistant
    1. methicillin resistant staph aureus (MRSA)
  • MecA resistance gene producing another transpeptidase
    2. vancomycin-resistant enterococci
  • cell wall is altered in AA side chain, prevents drug from binding
    3. carbapenem-resistant enterobacteriaceae
  • carbapenemase (penicillinase) breaks B-lactam ring
45
Q

drug resistance mechanisms

A
  1. preventing access, modifying target
    - outer membrane prevents drug from entering
    - altering TP
  2. inactivation of drug
    - penicillinase
  3. drug efflux
    - active transporters removing things from cells
    • some pump antibiotics out
46
Q

transmission of drug resistance

A
  • spontaneous DNA mutation
  • immunity genes
    • found in bacteria that produce antibiotics
    • share info with another cell via horizontal gene transfer (conjugation, transduction, transformation)
47
Q

overcoming drug resistance

A
  • give in appropriate concentrations
  • correct use by patient

Microbio (11 decks)

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