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IMIN 200 > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

What is a broad spectrum antibiotic?

A

Kills a lot of species of bacteria

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2
Q

What is a narrow spectrum antibiotic?

A

Kills few species of bacteria

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3
Q

Which type of antibiotic will have less of an ability to cause superinfection and why?

A

Narrow-spectrum because it will not kill as many of the normal microorganisms in the body and will cause less resistance

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4
Q

What is the problem with narrow-spectrum antibiotics?

A

You have to wait for a positive culture and sensitivity assay

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5
Q

What might an antibiotic target?

A

Cell wall synthesis
DNA replication enzymes
Bacterial ribosomes

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6
Q

How does penicillin target bacteria?

A

It blocks the transpeptidation step in PG synthesis

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7
Q

What does resistance evolve from?

A

Overuse and the lack of development of new antibiotics

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8
Q

What is bacterial transformation?

A

Uptake of free DNA from the environment

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9
Q

What does bacterial transformation require?

A

Sequence similarity for integration into genome

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10
Q

What is bacterial transduction?

A

Viral-mediated DNA exchange

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11
Q

How does bacterial transduction work?

A

A phage accidentally carries bacterial DNA and transfers that to the new host

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12
Q

What is bacterial conjugation?

A

The direct transfer of plasmid DNA between related species
Plasmid MAY contain resistance genes

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13
Q

What does repeat, short exposure to antibiotics lead to?

A

Natural selection in which bacteria that can survival antibiotic exposure will predominate

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14
Q

What happens to a population that is mixed with resistant and sensitive individuals?

A

Resistance can be shared by horizontal gene transfer

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15
Q

What are 4 mechanisms of antibiotic resistance?

A

Impermeable barrier
Multidrug resistance efflux pumps
Resistance mutations
Inactivation of the antibiotic

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16
Q

How does impermeable barriers cause resistance?

A

Antibiotics cannot penetrate the barrier or lacks the target of the antibiotic

17
Q

What are some examples of impermeable barriers?

A

Mycobacteria
Bacteria in a biofilm

18
Q

What are multidrug efflux pumps?

A

Pumps secrete antibiotics from the cell
Some transporters pump them right outside of the cell while Gram-negative bacteria will secrete them into the periplasm

19
Q

What does exposure to antibiotics increase?

A

The expression of endogenous pumps

20
Q

What are ABCs?

A

ATP-dependent general efflux pumps, broadest class

21
Q

What is an example of ABCs causing resistance?

A

E. coli resistance to chloramphenicol

22
Q

What is the major facilitator family (MFS) and what is an example involving resistance?

A

Proton-motive force-powered efflux pump
tetracycline resistance

23
Q

What is the resistant nodule family (NRD) and what is unique about it?

A

An efflux pump class
Only found in Gram-negative and is also found in P. aeruginosa

24
Q

What are resistance mutations?

A

Mutations that modify the target proteins of antibiotics

25
Q

What are 2 examples of resistance mutations?

A

Gyrase mutations = allow resistance to fluoroquinolones
Small ribosomal subunit = allows streptomycin resistance

26
Q

How does inactivation of antibiotics occur?

A

By covalent modification of the antibiotic

27
Q

What are 2 ways that an antibiotic could be inactivated?

A

Catalyzed by acetyltransferase acting on aminoglycoside antibiotics
Degradation of the antibiotic such as that catalyzed by beta-lactamases acting on beta-lactam antibiotics

28
Q

What are ESKAPE pathogens?

A

A group of highly antibiotic resistant bacterial pathogens which are responsible for a large portion of hospital acquired infections worldwide

29
Q

What does Enterococus faecium cause?

A

Blood infection
UTIs

30
Q

What is VRE and how does it work?

A

Vanomycin-resistant Enterococci
Vancomycin binds to D-ala-D-ala peptidoglycan peptide preventing transglycosylation and transpeptidation

31
Q

What is the resistance mechanism to vancomycin and how is resistance acquired?

A

Loss of D-lactate in linker peptide so the antibiotic no longer recognizes it
Resistance is acquired by a mutation in PG synthesis

32
Q

What are some examples of ESKAPE pathogens?

A

Enterococcus faecium
Ones that form biofilm (MRSA, P. aeruginosa, K. pneumoniae)
Enterobacter spp.
Ones with beta-lactamases

33
Q

What is beta-lactamase?

A

Enzymes produced by bacteria and provide resistance to beta-lactam antibiotics such as penicillins

34
Q

How do beta-lactamases inactivate penicillin?

A

By digestion

IMIN 200 (23 decks)

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