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MEDI > Microbial Control > Flashcards

Microbial Control Flashcards

1
Q

control of microbial growth types and order of less effective to most

A

cleaning
sanitation
disinfection
sterilisation

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2
Q

cleaning

A

Removal of visible soils such as food residues, dust, dirt, corrosion, scale and grease from a surface

Microorganisms are removed but not killed

Often achieved with water and detergent

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3
Q

sanitation

A

A process that destroys various microorganisms, reducing viable numbers on clean surfaces to meet
product quality and public health standards

Sanitisers are usually not effective in the presence of organic residues and detergents

Often achieved with moist heat (steam) or chemicals (chlorine)

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4
Q

disinfection

A

removal of pathogens only

The process of killing pathogenic organisms or rendering them inert

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5
Q

sterilisation

A

removal of all microbes including bacterial spores

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6
Q

germacide

A

– An agent that kills pathogenic microorganisms

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7
Q

2 types of germacide

A

Disinfectant

Antiseptics

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8
Q

disinfectant

A

A substance that removes or causes the destruction of harmful microbes (not usually spores), from inanimate objects

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9
Q

antiseptic

A

A disinfectant for animate areas

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10
Q

what are physical methods for inanimate object - disinfection

A

Heat (Pasteurisation)
Radiation
Heat

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11
Q

heat - pasteurisation (what, does, temps)

A

disinfection - physical method, inanimate

Typically in the range of 60-800C for a few minutes to kill pathogens and to destroy most other bacteria that cause food spoilage (i.e. preservation, to increase shelf life)

  • Low temp, Long time (LTLT) = 63 ̊C, 30 min
  • High temp, Short time (HTST) = 72 ̊C, 15 sec
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12
Q

who developed pasteurisation and what

A

Louis Pasteur - mid 1800s to prevent spoilage of wine

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13
Q

radiation

A

disinfection, physical method, inanimate
Ultra-violet (UV) radiation (usually non-ionising)
– Damages proteins & nucleic acid
– Low penetrating power
– Moderate exposure time (3 hours for a biosafety cabinet)
– Reduction of microbes in air, water & on surfaces

Infra red radiation (non-ionising)
Ionizing radiation (has enough energy to liberate an electron from an atom)
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14
Q

disinfection - chemicals are for

A

ome for animate use and some only for inanimate objects

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15
Q

modes of action for chemical disinfection

A
  • Protein coagulation/denaturation
  • Disruption of cell membrane
  • Chemical antagonism (inactivation of enzymes)
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16
Q

organic matter

A

– Urine
– Vomit
– Diarrhoea
– Sputum – Blood

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17
Q

modes of inhibition (disinfection) of organic matter

A
  1. Forms a precipitate with disinfectant - removes disinfectant from contact with bacteria
  2. Reacts with the disinfectant to produce a non-bactericidal agent(s)
  3. Coats bacteria - protects the bacteria from the disinfectant
18
Q

most common sterilisation method

A

moist heat under pressure (autoclaving)

19
Q

why are bacterial spores so hard to kill

A

bacterial spores are the most heat resistant and difficult to kill microbial structure

The thick spore coat protects from radiation and chemicals

20
Q

temperature achieved & exposure time important - for moist heat

A

15min @121 ̊C at 15psi above ambient atmospheric (most common)

21
Q

sterilisation indicators (moist heat)

A 
Autoclave printouts/monitoring
Biological - Spore strips
Autoclave tape (Bowie-Dick test)
22
Q

dry heat types sterilisation

A

Hot Air Oven (time and heat higher than autoclave)
Advantage - Good for glassware, oils, powders - Doesn’t blunt sharps

Incineration (bunsen)

23
Q

Chemical Sterilisation by Gases & Cold Sterilisation - mode of action

A

denaturation of proteins

24
Q

Chemical Sterilisation by Gases & Cold Sterilisation - examples

A

– Formaldehyde (gas)
– Glutaraldehyde (aqueous)
– Ethylene oxide (gas)
– Plasma sterilisation (hydrogen peroxide gas)

25
Q

Sterilisation by Moist Heat - mode of action

A

coagulation & denaturing of proteins

26
Q

Sterilisation by Filtration – fluids and air (fill out bacteria with pores of….)

A

pores of 0.45μm or less)

27
Q

Antibiotic is

A

Natural compounds produced by microorganisms that kill or inhibit other microorganisms
– Synthetic (Artificially made compounds)
– Semi-synthetic (Natural antibiotic compounds that have been artificially modified_

28
Q

Synergism is

A

Compounds that act together to enhance or improve effect

29
Q

Antagonism is

A

Compounds that act against each other to reduce effect

30
Q

Bacteriostatic is

A

Compounds that inhibit growth of microorganism (bugs still viable)

31
Q

Bactericidal is

A

Compounds that kill microorganisms

32
Q

Basic sites of action of antibacterial agents

A
  • Inhibitors of cell wall synthesis
  • Membrane-active antimicrobial agents
  • Inhibitors of DNA replication
  • Inhibitors of RNA synthesis
  • Inhibitors of ribosome function - protein synthesis
  • Metabolic inhibitors
33
Q

what does b-lactam group do and why so good

A

b-lactams inhibit the last stage of the cell wall production process

Because eukaryote cells (including humans) do not have a cell wall (only a plasma membrane) and no
peptidoglycan, the β-lactams work well in that they kill bacteria without damaging cells of the host (“Magic Bullets”)

34
Q

what is b-lactam not effective against

A

resting bacteria

35
Q

what causes antibiotic resistance

A
  • over-prescribing of antibiotics
  • patients not finishing their treatment that works
  • overuse of antibiotics in livestock and fish farming
  • poor infection control in hospitals + clients
  • lack of hygiene and poor sanitation
  • lack of new antibiotics being developed
36
Q

Antibiotics – Overprescription and Animal Use method of resistant

A
  • drug sensitive cells and drug resistant cells together
  • drug kills of the sensitive cells
  • patients stops taking antibiotics
  • those resistant cells now mutate
    most cells are now resistant

Use in intensive farming of animals as growth promoters
• Resistant animal strains of bacteria passed to consumers in foods

37
Q

Antibiotic creed is

A

practise for docs to decrease antibiotic resistance

38
Q

Antibiotic

A

M - microbiology guides therapy wherever possible
I - indications should be evidence based
N - narrowest spectrum required
D - dosage appropriate to the site and type of infection
M - minimise duration of therapy
E - ensure monotherapy in most cases

39
Q

WHO list of bacteria that pose the greatest risk to human health - critical priority

A

– Pseudomonas aeruginosa, carbapenem-resistant
– Enterobacteriaceae, carbapenem-resistant, ESBL-producing
– Acinetobacter baumannii, carbapenem-resistant

Carbapenems are powerful β-lactams with a broad spectrum of activity

40
Q

Antibacterial antimicrobials are ineffective against whatttttt

A

FUNGIIII

41
Q

fungi are difficult to treat because…

A

hey are eukaryotic and so have similar structures to human cells

– Treatment is usually long-term
– Toxicity can be a problem - kidneys, liver, bone marrow

42
Q

Anti-Viral Chemotherapy - what do types ummm

A

Drugs that bind free virus preventing entry
– Disoxaril for Rhinovirus (treatment for “colds”)

Prevention of uncoating of virus
– Amantadine for Influenza

Inhibit viral replication
– Aciclovir for Herpes
– Zidovudine (AZT) for HIV – Inhibit protein synthesis

Interfere with Viral release
– Zanamivir (Relenza) for Influenza

MEDI (7 decks)

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