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Microbiology > BacT lecture 4 > Flashcards

BacT lecture 4 Flashcards

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Biology 101 flashcards
1
Q

What is an antibiotic?

eg. gentamicin, streptomycin

A

A chemical substance produced by a *microorganism that inhibits the growth of or kills other microorganism

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2
Q

A chemical substance derived form a biological source or produced by chemical synthesis that kills or inhibits the growth of microorganisms

A

Antimicrobial agent

eg sulfonamide, enrofloxacin

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3
Q

When do we use antibiotics or antimicrobial agents?

A

When body’s normal defenses cannot prevent or overcome disease
Must act with in the host without damaging the host
Disinfectants and antiseptics act outside the body of the host

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4
Q

Who and how was penicillin discovered?

A

Alexander Fleming- It was an accident

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5
Q

Sources of Chemotherapeutic Antimicrobial Agents

A

Natural (true antibiotics)
Semi-synthetic
Synthetic

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6
Q

Where do Natural Antimicrobial Agents come from?

A

Fungal and bacterial
benzyl penicillin, gentamicin, streptomycin, chlortetracycline
Streptomyces, Bacillus, Penicillium

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7
Q

What are Semi-synthetic Antimicrobial Agents?

A

Chemically-altered natural compound

ampicillin, amikacin

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8
Q

What are Synthetic Antimicrobial Agents?

A

Chemically designed in the lab

sulfonamide, enrofloxacin, marbofloxacin

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9
Q

What are the classification of antimicrobial agents?

A

Chemical family structure
Mode of action
Type of antimicrobial activity
Spectrum of antibacterial activity

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10
Q

Draw the distinguishing characteristic of Beta Lactams

A

Refer to slide 8 of lecture 4 BacT

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11
Q

Mode of action (functional groups)

A 
Inhibitors of cell was synthesis
Inhibitors of protein synthesis
Inhibitors of nucleic acid synthesis
Inhibitors of membrane function
Anti-metabolites
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12
Q

Cell wall synthesis inhibitors

A

Beta lactam antibiotics

Penicillin, ampicillin, cephalosporins, carbapenem, monobactam

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13
Q

What do cell wall synthesis inhibitors beta lactam antibiotics work?

A

Inhibit peptidoglycan synthesis

Bind and inhibit a group of proteins called penicillin binding proteins

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14
Q

What is an enzyme present in bacteria which can cleave beta lactam ring and inactivate penicillin and contribute to resistance?

A

Beta Lactamase

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15
Q

Clauvulanic acid does what?

A

(suicide substrate) prevent degradation of penicillin by beta lactamase

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16
Q

Cell wall synthesis inhibitors Glycopeptides

A

Vancromycin, daptomycin
Last drugs of choice for some gram-pos bacteria
V resistance - increasing

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17
Q

Protein Synthesis inhibitors

A 
Aminoglycosides
Tetracyclins
Macrolides
Phenocols
Lincosamides
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18
Q

Antibiotic examples of Aminoglycosides and which protein subunit do they inhibit?

A

Gentamicin, amikacin, kanamycin, streptpmycin

30s subunit

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19
Q

Antibiotic examples of Tetracyclins and which protein subunit do they inhibit?

A

Oxytetracycline, chlortetracycline

30s subunit

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20
Q

Antibiotic examples of Macrolides and which protein subunit do they inhibit?

A

Erythromycin, azithromycin

50s subunit

21
Q

Antibiotic examples of Phenocols and which protein subunit do they inhibit?

A

Chloramphenicol

50s subunit

22
Q

Antibiotic examples of Lincosamides and which protein subunit do they inhibit?

A

Clindamycin

50s subunit

23
Q

DNA synthesis inhibitors

A

Quinolones

Metronidazole

24
Q

Examples if quinolone and what do they do?

A

Nalidixic acid, ciprofloxacin

*Inhibit enzyme DNA gyrase

25
Q

What is the resistance of quinolones due to?

A

A mutation in the gene for enzyme DNA gyrase

26
Q

What does metronidazole?

A

Makes breaks in the DNA

27
Q

What are the RNA synthesis inhibitors?

A

Rifampin

Mupirocin

28
Q

What does rifampin do?

A

Inhibit RNA polmerase (transcription)
Active against Mycobacterium tuberculosis
Extremely multidrug resistance TB

29
Q

What does mupirocin do?

A

Inhibit tRNA synthetase (translation)

Commonly used for MRSA

30
Q

What are the folic acid synthesis inhibitors and what do they do?

A

(antimetabolites)
Sulfonomides
Trimethoprim
Competitive inhibitors of dihydrofolate reductase

31
Q

Types of antimicrobial activity. What is Bacteriostatic Activity?

A

Inhibition of bacterial multiplication/growth

Visual inhibition of bacterial growth is the basis of routine susceptibility testing

32
Q

In a drug dilution series, the lowest drug concentration that completely *inhibits bacterial growth is?

A

Minimal Inhibitory Concentration (MIC)

33
Q

In a drug dilution series, the lowest drug concentration that *kills the bacterial population is?

A

Minimal Bactericidal Concentration (MIB)

34
Q

Broad vs Narrow spectrum antibiotics

A

Broad spectrum active against a wide variety of bacteria (Tetracycline)
Narrow spectrum only work on a select few bacteria (Penicillin)

35
Q

How do you know certain bacteria is susceptible to a particular antibacterial?

A

Antibacterial Susceptibility Testing; either Dilution or Diffusion

36
Q

Disk Diffusion (Kirby Bauer testing)

A

Single- concentration disk
Growth inhibition zone diameter measured
Use published reference break points to interpret results

37
Q

Broth Dilution

A

One to multiple dilutions of antibiotic
Measure and report growth inhibition endpoint (MIC)
Use published references breakpoints to interpret
Susceptible, Intermediate, Resistant

38
Q

Susceptibility Results

A

S- High likelihood of therapeutic success
I- Uncertain therapeutic outcome
R- High likelihood of therapeutic failure

39
Q

In MRSA and Pseudomonas aeruginosa, targeting quorum sensing provides for

A

Regulatory control over genes

40
Q

4 types of horizontal gene transfer

A

Lysogenic conversion (transduction)
Transduction (generalized transduction)
Conjugation
Transformation

41
Q

Lysogenic conversion (transduction)

A

Bacterphage DNA into a bacteria cell

42
Q

Transduction (generalized transduction)

A

bacterial DNA into another bacteria via virus

43
Q

Conjugation

A

Plasmids

44
Q

Transformation

A

Uptake of exogenous DNA

45
Q

Mobile genetic elements

A

Insertion sequences

Transposons

46
Q

Types of resistance

A

Innate - preexisting genomic property
Acquired - new genetically encoded trait not representative of the species (acquired by mutation or horizontal gene transfer

47
Q

Mechanisms of resistance

A

Enzymatic destruction or inactivation of drug
Prevention of penetration to target sites within microbe
Alteration of drugs target site
Rapid efflux of antibiotics

48
Q

Consequences of antimicrobial resistance

A

Increased mortality to infectious disease
Increased nosocomial infections
High treatment costs
Decreased development of new drugs

49
Q

Almost all bacterial are acquiring resistance to antibacterial because

A 
Widespread antimicrobial use
Microbial adaptation and change
Change in demographics
Medical advances
Change in ecosystems
Cutbacks in public health systems and surveillance

Microbiology (15 decks)

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