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BacT lecture 4 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
What is the resistance of quinolones due to?
A mutation in the gene for enzyme DNA gyrase
26
What does metronidazole?
Makes breaks in the DNA
27
What are the RNA synthesis inhibitors?
Rifampin | Mupirocin
28
What does rifampin do?
Inhibit RNA polmerase (transcription) Active against Mycobacterium tuberculosis Extremely multidrug resistance TB
29
What does mupirocin do?
Inhibit tRNA synthetase (translation) | Commonly used for MRSA
30
What are the folic acid synthesis inhibitors and what do they do?
(antimetabolites) Sulfonomides Trimethoprim Competitive inhibitors of dihydrofolate reductase
31
Types of antimicrobial activity. What is Bacteriostatic Activity?
Inhibition of bacterial multiplication/growth | Visual inhibition of bacterial growth is the basis of routine susceptibility testing
32
In a drug dilution series, the lowest drug concentration that completely *inhibits bacterial growth is?
Minimal Inhibitory Concentration (MIC)
33
In a drug dilution series, the lowest drug concentration that *kills the bacterial population is?
Minimal Bactericidal Concentration (MIB)
34
Broad vs Narrow spectrum antibiotics
Broad spectrum active against a wide variety of bacteria (Tetracycline) Narrow spectrum only work on a select few bacteria (Penicillin)
35
How do you know certain bacteria is susceptible to a particular antibacterial?
Antibacterial Susceptibility Testing; either Dilution or Diffusion
36
Disk Diffusion (Kirby Bauer testing)
Single- concentration disk Growth inhibition zone diameter measured Use published reference break points to interpret results
37
Broth Dilution
One to multiple dilutions of antibiotic Measure and report growth inhibition endpoint (MIC) Use published references breakpoints to interpret Susceptible, Intermediate, Resistant
38
Susceptibility Results
S- High likelihood of therapeutic success I- Uncertain therapeutic outcome R- High likelihood of therapeutic failure
39
In MRSA and Pseudomonas aeruginosa, targeting quorum sensing provides for
Regulatory control over genes
40
4 types of horizontal gene transfer
Lysogenic conversion (transduction) Transduction (generalized transduction) Conjugation Transformation
41
Lysogenic conversion (transduction)
Bacterphage DNA into a bacteria cell
42
Transduction (generalized transduction)
bacterial DNA into another bacteria via virus
43
Conjugation
Plasmids
44
Transformation
Uptake of exogenous DNA
45
Mobile genetic elements
Insertion sequences | Transposons
46
Types of resistance
Innate - preexisting genomic property Acquired - new genetically encoded trait not representative of the species (acquired by mutation or horizontal gene transfer
47
Mechanisms of resistance
Enzymatic destruction or inactivation of drug Prevention of penetration to target sites within microbe Alteration of drugs target site Rapid efflux of antibiotics
48
Consequences of antimicrobial resistance
Increased mortality to infectious disease Increased nosocomial infections High treatment costs Decreased development of new drugs
49
Almost all bacterial are acquiring resistance to antibacterial because
``` 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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