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Microbiology > Lecture 4: Antibiotics and Antibiotic resistance > Flashcards

Lecture 4: Antibiotics and Antibiotic resistance Flashcards

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Biology 101 flashcards
1
Q

This is a class of chemotherapeutic agents

A

Antibiotics

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2
Q

These are chemical compounds used to treat disease

A

Chemotherapeutic agents

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2
Q

These destroy pathogenic microbes or inhibit their growth within the host

A

Antimicrobials

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3
Q

This is the ability of drugs to kill or inhibit pathogens while damaging the host as little as possible

A

Selective toxicity

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4
Q

This is the drug level required for clinical treatment

A

Therapeutic dose

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4
Q

This is the drug level at which the drug becomes too toxic for patients

A

Toxic dose

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5
Q

This is the ratio of a toxic dose to a therapeutic dose

A

Therapeutic index

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5
Q

These destroy or inhibit bacteria

A

Antibiotics

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6
Q

In dilution susceptibility tests, broth from which microbe cannot be recovered is

A

MBC

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6
Q

In disk diffusion tests, clear zones indicate

A

No growth

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6
Q

What kind of antibiotics attach many different bacteria?

A

Broad-spectrum antibiotics

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7
Q

Bacteriostatic antibiotics

A

inhibit the growth of bacteria

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7
Q

Bactericidal antibiotics

A

Kill bacteria

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7
Q

What are the factors influencing the ability of the drug to reach concentrations exceeding MIC?

A

a. Amount administered
b. Route of administration
c. The speed of uptake
d. The rate of clearance from the body

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7
Q

This is the lowest concentration of the drug that kills the pathogen

A

MBC

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7
Q

What kind of antibiotics attack only a few bacteria?

A

Narrow-spectrum antibiotics

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7
Q

This is the lowest concentration of the drug that inhibits the growth of the pathogen

A

MIC

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8
Q

In dilution susceptibility tests, the broth or agar with the lowest concentration showing growth is

A

MIC

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9
Q

What is the standardized method for carrying out disk diffusion tests?

A

Kirby-Bauer method

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10
Q

When doing a disk diffusion test, what are we measuring?

A

Zone of inhibition

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11
Q

What factors influence the effectiveness of antimicrobial drugs?

A

a. The ability of the drug to reach the site of infection
b. The ability of the drug to exceed MIC
c. Susceptibility of the pathogen to drug

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11
Q

The concentration of a drug at an infection site must be _______ to be effective

A

> MIC

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12
Q

What are the different ways you can administer a drug?

A

a. Oral
b. Topical
c. Parenteral routes

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13
Q

What is the most common mechanism of bacterial resistance to penicillins?

A

Hydrolysis of B-lactam ring by B-lactamase

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13
Q

What are the types of B-lactams?

A

a. Penicillin
b. Cephalosporin
c. Carbapenems
d. Monobactams

14
Q

What creates crosslinks in peptidoglycans?

A

Transpeptidation

14
Q

What is not a B-lactam?

A

Tetracycline

14
Q

Do gram-negative or positive forms a peptide interbridge?

A

Gram-positive

14
Q

Describe peptidoglycan synthesis

A

a. UDP as a carrier
b. Transported across the membrane by bactoprenol
c. Cross-linked via transpeptidation

14
Q

B-lactam antibiotics do inhibit

A

Transpeptidation

14
Q

What are examples of B-lactamase inhibitors?

A

a. Clavulanic acid
b. Sulbactam
c. Tazobactam

15
Q

Describe the key components of Augmentin in treating a bacterial infection.

A

Augmentin = amoxicillin + clavulanic acid (B-lactamase inhibitor)

16
Q

What antibiotic binds the terminal D-Ala-D-Ala of peptide side chains of peptidoglycan subunits,
sterically inhibiting the addition of new subunits to the cell wall?

A

Vancomycin

17
Q

What antibiotic has been important for the treatment of antibiotic-resistant staphylococcal and enterococcal infections?

A

Vancomycin

18
Q

These polypeptides prevent the recycling of lipid carriers

A

Bacitracin

19
Q

These polypeptides bind phospholipids and disrupt the outer and inner membranes of gram-negative bacteria

A

Polymixins

20
Q
  1. This is an antibiotic that crosses the blood-brain barrier and is an NMDA receptor agonist and a 2nd line treatment for mycobacterium
A

Cycloserine

21
Q

These drugs inhibit mycobacteria by affecting the synthesis of mycolic acid

A

a. Isoniazid
b. Ethionamide

21
Q

These drugs inhibit mycobacteria by affecting the attachment of mycolic acid in the cell wall

A

Ethambutol

22
Q

These drugs bind 23S rRNA and prevent the formation of 70S initiation complex

A

Oxazolidionones

23
Q

These bind 16S rRNA of 30S subunits and prevent the binding site of aa-tRNA to the A site

A

Tetracyclines

24
Q

What is a common mechanism of bacterial resistance to tetracyclines?

A

activation/acquisition of a drug efflux pump

25
Q

These bind to the 30S subunit and distort the A site, causing translation misreading, which
inhibits protein synthesis

A

Aminoglycosides

26
Q

What is the basis of the antibiotic activity of chloramphenicol/linosamides?

A

Bind to the 50S subunit and inhibit peptidyltransferase activity

27
Q

These bound 23S rRNA in the 50S subunit and block the translocation reaction which also
prevents the formation of the 50S subunit

A

Macrolides ( Erythromycin)

28
Q

What is a common mechanism of bacterial resistance to quinolones?

A

mutations in DNA gyrase gene or topoisomerase IV

29
Q

This binds to RNA polymerase and prevents the initiation of transcription

A

rifampin/rifabutin

29
Q

These interfere with type 2 topoisomerases and stabilize DNA double-strand breaks

A

Quinolones

30
Q

What is the mechanism of action for penicillin?

A

Inhibits transpeptidation

31
Q

What drug has no inherent antimicrobial activity?

A

Metronidazole

31
Q

This produces DNA-damaging radicals under anaerobic conditions via enzymes functioning in
anaerobes and microaerophiles

A

Metronidazole

32
Q

What antibiotics inhibit folic acid synthesis?

A

Sulfanilamide

33
Q

What are the resistance mechanisms for penicillins and cephalosporins?

A

Hydrolysis of B-lactam ring by B-lactamase

34
Q

What is the resistance mechanism for methicillin?

A

Changes in penicillin-binding proteins

35
Q

What is the resistance mechanism for oxazolidinones?

A

Mutations in 23S rRNA

36
Q

What is the resistance mechanism for vancomycin?

A

Change in the binding site in the peptidoglycan target

36
Q

What unique mechanism for transferring antibiotic resistance genes could occur at a relatively
high frequency for a gene on a bacterial chromosome adjacent to a phage genome insertion site?

A

transduction

37
Q

What mechanism is present for transferring antibiotic resistance genes occurs for genes that are
on bacterial chromosomal DNA present in the local environment due to bacterial cell death and lysis

A

Transformation

38
Q

What are strategies for preventing emerging drug resistance?

A

a. Give high concentrations
b. Give 2 or more drugs at once
c. Only use drugs when necessary

39
Q

What is the primary mechanism for transferring antibiotic resistance genes present on R plasmid
within drug-resistant bacteria?

A

Conjugation

39
Q

What are the 3 ways that antibiotic resistance genes can be transferred at high frequencies from
one bacterium to another?

A

a. Conjugation (sex plasmid)
b. Transduction (phage)
c. Transfomation (naked DNA)

Microbiology (6 decks)

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