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BMSC 210 > Module 8 - Notes > Flashcards

Module 8 - Notes Flashcards

1
Q

What are the 3 main methods of microbial control?

A

Physical

Mechanical Removal

Chemical

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2
Q

What are the 2 categories of physical microbial control?

A

Heat

Radiation

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3
Q

What are the 2 categories of Heat to control microbial infection?

A

Dry Heat - Like oven

Moist Heat - Like Boiling of autoclave

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4
Q

What types of microbial controls do you use on inanimate items (non-living)

A

Sterilization

Disinfection

Sanitization

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5
Q

What types of microbial controls do you use on living tissues?

A

Antiseptics

Degerming

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6
Q

What is sterilization?

A

Completely eliminate all vegetative cells, endospores and viruses

Eliminates all microbial risk

Only used on inanimate items.

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7
Q

What is Disinfection?

A

Reduces or destroys microbial load using heat or chemicals.

(there can still be some bacterial life)

Only used on inanimate items

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8
Q

What is Sanitization?

A

Reduces microbial loads to a safe public health level using heat or chemicals

Only used on inanimate items

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9
Q

What is Antisepsis?

A

Reduces microbial load using antimicrobial chemicals on living tissues

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10
Q

What is degerming?

A

Reduces microbial load using scrubbing and mild chemicals on living tissues.

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11
Q

You have injured your arm and your sibling tells you that you must sterilize your would. Why are they wrong?

A) Sterilization is a process that uses scrubbing and you could damage the wound

B) Sterilization is a process exclusively used on inanimate objects

C) Sterilization will only reduce the microbial load without killing the pathogen.

D) Sterilization absolutely requires heat to completely destroy the microbes.

A

B) Sterilization is a process exclusively used on inanimate objects

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12
Q

What are the 2 categories of radiation for the physical methods of microbial control?

A

Nonionizing - UV

Ionizing - Xray

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13
Q

Dry heat methods for microbial control include a dry oven and incineration (flame). What level of microbial control is achieved with either method?

A

Sterilization

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14
Q

Moist heat methods for microbial control include autoclave (steam & pressure) and boiling water or pasteurization. What level of control is achieved with autoclaves?

A

Sterilization
but only if held at 121 degrees Celcius for 15 minutes or more.

15 minutes is how long it takes to kill spores

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15
Q

Moist heat methods for microbial control include autoclave (steam & pressure) and boiling water or pasteurization. What level of control is achieved with boiling water of pasteurization?

A

Disinfection

Reduces bacterial loads but only eliminates heat-sensitive pathogens.

Not sterile

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16
Q

What is HTST Pasteurization of milk?

A

High temp short time

milk is heated to 72 degrees celsius for 15 seconds then bottled and refrigerated.

Shorter shelf life

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17
Q

What is UHT pasteurization for milk?

A

Ultra High Temperature

Milk is heated to 138 degrees celsius or more for 2 or more seconds, then sealed in airtight containers for up to 90 days without refrigeration. (tetra pack milk)

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18
Q

What other physical methods of microbial control can be used besides heat or pressure?

A

Cold - Refrigeration or freezing

Dessication - Drying

Both methods just control growth. They do not reduce the population by killing.

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19
Q

For a research project, you pasteurized your growth medium. Once the process is complete, you leave your flask on the bench to cool down. After a few days, you notice growth in your medium, what is the best explanation?

A

The aim of pasteurization is to reduce the microbial population to a safe level; therefore you do not sanitize your growth medium.

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20
Q

What is an example of a mechanical process to control microbial growth?

A

Filtration.

Effectiveness depends on pore size

HEPA filters have a 0.3 micron pore size. (used to remove microbes from air)

Membrane filters have a 0.2 micron pore size or smaller. (Used in liquid solutions)

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21
Q

What are the 2 categories of chemical microbial control?

A

Gases

Liquids

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22
Q

Gases used in chemical methods of microbial control can achieve what level of control?

A

sterilization or disenfection

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23
Q

What are the examples of liquid chemical controls used on living tissues?

A

Chemotherapy (taken internally)
- Antibiotics
- antivirals
- Antiparasitic
- Antifungal

Antisepsis (Applied topically)

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24
Q

What are the 3 main categories of antimicrobial agents?

A

Static (stops growth)
Cidal (kills)
Lytic (Lyses)

examples
bacteriostatic/cidal/lytic -targets bacteria
fungistatic/cidal - targets fungi
viricistatic/dal - targets viruses
sporocidal - targets spores

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25
Q

How do we determine the effects of antimicrobial agents?

A

Use plate counts and optical denisty

With a static agent, the optical density and number of colony forming units will plateau once the agent is applied

With a cidal or lytic agent, the optical density and the number of colony forming units will decrease once the agent is applied.

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26
Q

How do we test the effectiveness of antiseptics and disinfectants?

A

Use the disc diffusion assay method

A plate is inoculated with various antimicrobial discs.

The zone of inhibition around each disc indicates how effective that antimicrobial is against the particular species being tested.

The larger zone = more it kills

can only tell you how much it kills

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27
Q

How do we test the efficacy of germicides?

A

logarithmic scale - overtime how much is decreasing. The steeper the curve, the more effective it is.

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28
Q

How many bacteria can a compound with 99.999% efficacy kill?

A) 10 000 and above

B) 100 000 and below

C) 100 000 and above

D) 1 million

E) 1 billion

A

B) 100 000 and below

Count the number of 9’s and then count the number of 0’s

5 nines = 5 zeros

Something that kills 99.9% is not as effective as something that kills 99.99%

99.9% is up to 1000

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29
Q

What is the difference between physical methods, chemical methods and filtration to control microbes?

A

Physical methods and chemical methods reduce populations and/or inhibit growth. Filtration removes microbes

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30
Q

You work with a food-borne human pathogen that is psychrotolerant bacteria. What storage temperature would you use to make sure the food stays safe?

A

Below refrigeration temperature

Psychrotolerants are mesophiles that can grow at refrigeration temperature

Human pathogen must grow at body temperature

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31
Q

What are the considerations when using a chemotherapy?

A

Toxicity towards the host - dosage and route of administration

  • Kill or inhibit pathogen without damaging the host
  • Easier for bacteria, harder for viruses and very hard for eukaryotic pathogen
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32
Q

What is a broad-spectrum vs narrow-spectrum antibody?

A

Broad-spectrum - kills many different groups, indiscriminate - kills the good and bad bacteria

Narrow-spectrum - kills specific groups of bacteria

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33
Q

What is an antibiotic?

A

chemical substance that kills bacteria or prevents bacterial growth

the familiar/current definition is an umbrella term for antibacterial compounds but classically:
1. antibacterial
2. produced naturally by microorganisms
3. a chemical not a protein

34
Q

What are the targets of antibiotics?

A

Cell wall

Plasma membrane

Ribosomes

Metabolic pathways

DNA synthesis

RNA synthesis

35
Q

If we use an antibiotic to inhibit cell wall biosynthesis what are the targets?

A

Penicillin-binding proteins

Peptidoglycan subunits

Peptidoglycan subunit transport

36
Q

If we use an antibiotic to inhibit biosynthesis of proteins what are the targets?

A

30S ribosomal subunit

50S ribosomal subunit

37
Q

If we use an antibiotic to disrupt membranes what are the targets?

A

Lipopolysaccharide, inner and outer membranes

38
Q

If we use an antibiotic to inhibit nucleic acid synthesis what are the targets?

A

RNA

DNA

39
Q

If we use an antibiotic for antimetabolites what are the targets?

A

Folic acid synthesis enzyme

Mycolic acid synthesis enzyme

40
Q

If we use an antibiotic as a mycobacterial adenosine triphosphate (ATP) synthase inhibitor what are the targets?

A

Mycobacterial ATP synthase

41
Q

A patient wth a pneumonic receives a beta lactam but their condition does not improve, the patient is given a macrolide and they fully recover. What is the explanation?

A

The patient was infected with a mycoplasma pneumoniae.

42
Q

What antibiotics target the cell wall

A

Beta-lactams
- penicillins
- cephalosporins
- monobactams
- carbapenems

Glycopeptides
- vancomycin

Bacitracin

43
Q

What antibiotics target the plasma membrane?

A

Polymyxins
- polymixin B
- colistin

Lipopeptide
- daptomycin

44
Q

What antibiotics target the Ribosomes?

A

30S subunit
- aminoglycosides
- tetracyclines

50S subunit
- macrolides
- lincosamides
- chloramphenicol
- oxazolidinones

45
Q

What antibiotics target DNA synthesis?

A

Fluoroquinolones
- ciprofloxacin
- levofloxacin
- moxifloxacin

46
Q

What antibiotics target RNA synthesis?

A

Rifamycins
- rifampin

47
Q

What antibiotics target Metabolic pathways?

A

Folic acid synthesis
- sulfonamides
- sulfones
- trimethoprim

Mycolic acid synthesis
- izoniazid

48
Q

You are trying to prevent fungus infection in the hospital. What type of activity should your antimicrobial agent have if it is used to sterilize surfaces in a hospital room?

A) Bactericidal

B) Fungistatic

C) Fungicidal

D) Viricidal

A

C) Fungicidal

49
Q

What mechanisms do antifungal drugs use?

A

inhibit ergosterol synthesis

bind ergosterol in the cell membrane and create pores that disrupt the membrane

inhibit cell wall synthesis

inhibit microtubules and cell division

Lots of fungal infections are skin-based or nail-based so we can use fairly caustic chemicals to treat them

50
Q

Your patient asks you to explain why Ivermectin cannot be used to treat SARS-CoV-2 infections and can only be used against parasitic worms. How do you respond?

A

The target of Ivermectin are present in invertebrate nerve and muscle cells, and are not present in viruses.

51
Q

How do antiviral drugs work?

A

You want to target viral enzymes that modify their nucleotides

By adding nucleotide analogues, we’re able to prevent synthesis of micro RNAs or other things made by the virus

52
Q

What mechanisms of action do antivirals depend on?

A

Nucleotide analog inhibition of nucleic acid synthesis

Non-nucleoside noncompetitive inhibition

Inhibt escape of virus from endosomes

Inhibit neuraminadase

Inhibit viral uncoating

Inhibition of protease

Inhibition of integrase

Inhibition of membrane fusion

53
Q

What are some antimicrobial susceptivity tests?

A

Dilution Test

the lowest dilution that inhibits turbidity (cloudiness) is the MIC. minimal inhibitory concentration

In this example, the MIC is 8 μg/mL.

Broth from samples without turbidity can be inoculated onto plates lacking the antimicrobial drug.

The lowest dilution that kills ≥99.9% of the starting inoculum is observed on the plates is the MBC. minimal bactericidal concentration

54
Q

What is a microdilution tray?

A

A microdilution tray can also be used to determine MICs of multiple antimicrobial drugs in a single assay.

In this example, the drug concentrations increase from left to right and the rows with clindamycin, penicillin, and erythromycin have been indicated to the left of the plate.

For penicillin and erythromycin, the lowest concentrations that inhibited visible growth are indicated by red circles and were 0.06 μg/mL for penicillin and 8 μg/mL for erythromycin.

For clindamycin, visible bacterial growth was observed at every concentration up to 32 μg/mL and the MIC is interpreted as >32 μg/mL.

55
Q

What is an E-Test?

A

The E-test can be used to determine the MIC of an antibiotic.

In this E-test, vancomycin is shown to have a MIC of 1.5 μg/mL against Staphylococcus aureus.

56
Q

When measuring the activity of antimicrobial compounds, what is the difference between efficacy and susceptibility?

A) There is no difference

B) How fast it fills vs. how much it inhibits growth

C) How much it kills vs. how much it inhibit growth

D) How fast it kills and how much it kills vs. the concentration required to kill/inhibit growth.

A

D) How fast it kills and how much it kills vs. the concentration required to kill/inhibit growth.

Efficacy = how fast and how much

Susceptibility = the concentration required

57
Q

What are the 7 mechanism of antibiotic resistance?

A

Efflux pump

Blocked penetration

Inactivation of enzymes

Target modification

Overproduction of target

Production of alternate enzymes

Target mimicry

58
Q

You sequenced an antibiotic resistant gram-negative bacterium that is a lysogen. You observed that the antibiotic is quickly degraded by the bacterial cells. What type of mechanism is mediating the antibiotic resistance and how was it acquired?

A) Enzymatic inactivation acquired via conjugation

B) ABC efflux pump acquired via transduction

C) Enzymatic inactivation acquired by transduction

D) Target modification acquired via conjugation

A

C) Enzymatic inactivation acquired by transduction

59
Q

What is a superbacteria?

A

bacteria resistant to most antibiotics used to treat infections

60
Q

What is antibiotic stewardship?

A

an effort to follow evidence-based antibiotic usage to stop antimicrobial overuse and slow antimicrobial resistance

61
Q

What is epidemiology?

A

the study of the occurrence, distribution, and determinants of health and disease in a population

goal - identify the nature of disease and transmission

surveillance and reporting to trace the spread of a disease

62
Q

What is public health concerned with?

A

Health of the population as a whole

Their goal is to keep the population healthy
- slow or stop the spread of infectious disease.

63
Q

What is mortality?

A

incidence of death in a popultion

64
Q

What is morbidity?

A

incidence of disease (fatal, non-fatal, severe, mild)

65
Q

What is DALY (Disability-adjusted life year)

A

disease burden in terms of lost years due to disease, disability and/or premature death

66
Q

What is the effect of morbidity on the Disease-adjusted life year (DALY)?

A

It has a negative effect as it decreases the quality of life of individuals.

67
Q

What does prevalence mean in terms of epidemiology

A

it’s the total number of cases (new and existing) in a given time

68
Q

What does incidence mean in terms of epidemiology

A

it’s the total number of new cases in a given time.

69
Q

What does epidemic mean in terms of epidemiology?

A

a large number of people in a population are affected

70
Q

What does pandemic mean in terms of epidemiology?

A

A widespread, usually worldwide population is affected.

71
Q

What does endemic mean in terms of epidemiology?

A

It is constantly present in a population. Presence of a reservior.

72
Q

The presence of a constant reservoir in a given population.

A) What is an epidemic?
B) What is a pandemic?
C) What is endemic?
D) What is prevalence?
E) What is incidence?

A

C) What is endemic

73
Q

What is a reservoir?

A

“Normal/natural” habitiat of an infectious microbe

  • Animal Reservoir = zoonotic disease
  • Environmental Reservoir = sapronosis
    (present in water, soil, erc)
  • Human Reservoir = human only disease
74
Q

What is zooanthroponosis?

A

humans can give disease to animals

ie. mastitis in dairy cows

75
Q

What are mechanisms of transmission for disease?

A
  1. Contact Transmission
    - direct (physical)
    - indirect (via an intermediate carrier)
    vehicles like food
    fomites like door knobs
    vectors like mosquitos
  2. Droplet Transmission
    - travel less than 1m from the source
    sneezing
  3. Airborne Transmission
    - travel more than 1m and stay suspended for hours
    microbes that freely float
76
Q

How can we prevent the spread of infectious diseases?

A
  1. Eliminate the reservior
    - Animal (immunize or slaughter)
    - Environment (Decontaminate or avoid)
    - Human (identify, isolate & treat infected host)
  2. Limit the availability of new hosts
    - improve living condition, general health & safety
    - Vaccination
  3. Block routes of transmission
    - Indirect contact
    clean water, prevent food contamination
    remove vectors
    clean fomites
    - Airborne
    flow system to prevent dispersal
    - Droplets & direct contact
    wash hands
    Barriers like gloves, gowns, masks
77
Q

What are asymptomatic individuals?

A

Individuals who are affected by microbial infection but show no symptoms.

78
Q

What is the swiss cheese method of controlling microbes?

A

Using multiple strategies to reduce the risks of infection.

79
Q

What are the challenges associated with preventing the spread of infectious disease?

A

Natural progression of an infection
- asymptomatic carriers vs. pre-symptomatic
Vaccine compliances
Reservoirs
Social Pressure
- working while sick

80
Q

What are the most effective methods to decrease infectious disease incidence?

A
  1. Clean drinking water supply
  2. Clean food supply
  3. Promoting sanitization and personal hygiene
  4. Controlling insect vectors
  5. Public education about STIs and respiratory disease
81
Q

What are the current issues in public health practices?

A
  1. Global disparity in preventing infectious disease
  2. New infectious disease continue to appear
    - microbes mutate and evolve
    - spillover events (zoonosis)
    - global warming and travel

BMSC 210 (24 decks)

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