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PHA112 > Microbiology 9 - Antimicrobials > Flashcards

Microbiology 9 - Antimicrobials Flashcards

1
Q

List the 7 main groups of antibiotics

A
  • Penicillins
  • Cephalosporins
  • Macrolides
  • Fluoroquinolones
  • Sulfonamides
  • Tetracyclines
  • Aminoglycosides
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2
Q

Antibiotics must be more ____ to _____ than ____-

A

toxic
microorganism
host

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3
Q

What do all B-lactams have?

A

B-lactam ring

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4
Q

Sulphonamides inhibits _____

A

DHPS

enzyme involved in folate synthesis

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5
Q

What do bacteriostatic agents do?

A

They halt growth, but bacteria recover when drug stopped e.g. tetracycline

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6
Q

What do bactericidal agents do?

A

They kill bacteria for a period of time e.g. b-lactam

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7
Q

Conc dependent drugs rate of kill becomes _____

A

constant

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8
Q

What is broad spectrum?

A

Effective against a wide range of bacterial species

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9
Q

What is narrow spectrum?

A

Effective against a limited number of bacterial species

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10
Q

What needs to be considered when choosing antibiotics?

A
  • Selectivity (treat what needed?)
  • Toxicity (will it poison?)
  • Therapeutic index (Toxic dose/ effective dose?)
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11
Q

What is disinfection?

A

Removes microbes from inanimate surfaces e.g. ethanol

Broad spec

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12
Q

What is antisepsis?

A

Removes microbes from living surfaces
Used to reduce microbial populations
Broad spec

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13
Q

What is preservation?

A

Substance added to product to prevent growth + degradation by microbes/ unwanted chemical changes

Used to increase shelf life in pharmaceuticals

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14
Q

What is osmosis?

A

Net movement of a solvent from high to low concentrations through a membrane

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15
Q

What is water activity (Aw)?

A

Proportion of uncomplexed water available to support microbial growth

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16
Q

What are the Aw values for bacteria & yeasts?

A

Bacteria = 0.9-0.95
Yeasts & moulds: 0.8-0.88
No microbial growth ≤0.6

17
Q

Name and describe the process that can reduce Aw

A

Desiccation - removal of water vapour from products

18
Q

What is minimum inhibitory concentration (MIC)?

A

Lowest concentration of chemical which prevents visible growth of a bacterium

19
Q

What is minimum bactericidal concentration (MBC)?

A

Lowest conc of an antibacterial agent required to kill a particular bacterium

20
Q

What is innate resistance?

A

Inherent ability of bacterial to resist a particular antibiotic (e.g. lack of cell wall)

21
Q

What is acquired resistance and name 3 ways in which this can occur?

A

Result of changes to normal genome of bacteria

  • transformation
  • transduction
  • conjugation
22
Q

List 3 types of antibiotic resistance mechanisms

A
  • Exclusion
  • Inactivation
  • Target modification
23
Q

List alternatives to antimicrobial agents

A
  • Natural products

- Bacteriophages & derived products

24
Q

Give an example of antibiotics that work as an antibiotic & disinfectant

A

Efflux pumps

25
Q

What type of inhibitor are sulphonamides?

A

competitive

26
Q

In concentration dependent bactericidal drugs, why does the rate of kill eventually become constant?

A

limited by agent diffusion

27
Q

When is Isoniazid a bacteriostatic drug?

A

Lag phase and dormant mycobacteria

28
Q

When is Isoniazid a bactericidal drug?

A

Log phase mycobacteria

29
Q

Misuse of antibiotics leads to risk of _______

A

resistance

30
Q

Antiseptics must be non-____

A

non-toxic

31
Q

The concentration of the active ingredient in antiseptics is lower/higher than in disinfectants

A

lower

32
Q

Where can resistance genes come from?

A
  • bacteria having survived antibiotic treatment
  • antibiotic producers
  • bacteria that exist alongside antibiotic producers
33
Q

What are the 3 main ways in which bacteria obtains acquired resistance?

A
  • transformation
  • transduction
  • conjugation

PHA112 (16 decks)

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