Antibiotics

Question 1

What is a broad spectrum antibiotic?

Answer 1

Kills a lot of species of bacteria

Question 2

What is a narrow spectrum antibiotic?

Answer 2

Kills few species of bacteria

Question 3

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

Answer 3

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

Question 4

What is the problem with narrow-spectrum antibiotics?

Answer 4

You have to wait for a positive culture and sensitivity assay

Question 5

What might an antibiotic target?

Answer 5

Cell wall synthesis
DNA replication enzymes
Bacterial ribosomes

Question 6

How does penicillin target bacteria?

Answer 6

It blocks the transpeptidation step in PG synthesis

Question 7

What does resistance evolve from?

Answer 7

Overuse and the lack of development of new antibiotics

Question 8

What is bacterial transformation?

Answer 8

Uptake of free DNA from the environment

Question 9

What does bacterial transformation require?

Answer 9

Sequence similarity for integration into genome

Question 10

What is bacterial transduction?

Answer 10

Viral-mediated DNA exchange

Question 11

How does bacterial transduction work?

Answer 11

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

Question 12

What is bacterial conjugation?

Answer 12

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

Question 13

What does repeat, short exposure to antibiotics lead to?

Answer 13

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

Question 14

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

Answer 14

Resistance can be shared by horizontal gene transfer

Question 15

What are 4 mechanisms of antibiotic resistance?

Answer 15

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

Question 16

How does impermeable barriers cause resistance?

Answer 16

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

Question 17

What are some examples of impermeable barriers?

Answer 17

Mycobacteria
Bacteria in a biofilm

Question 18

What are multidrug efflux pumps?

Answer 18

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

Question 19

What does exposure to antibiotics increase?

Answer 19

The expression of endogenous pumps

Question 20

What are ABCs?

Answer 20

ATP-dependent general efflux pumps, broadest class

Question 21

What is an example of ABCs causing resistance?

Answer 21

E. coli resistance to chloramphenicol

Question 22

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

Answer 22

Proton-motive force-powered efflux pump
tetracycline resistance

Question 23

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

Answer 23

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

Question 24

What are resistance mutations?

Answer 24

Mutations that modify the target proteins of antibiotics

Question 25

What are 2 examples of resistance mutations?

Answer 25

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

Question 26

How does inactivation of antibiotics occur?

Answer 26

By covalent modification of the antibiotic

Question 27

What are 2 ways that an antibiotic could be inactivated?

Answer 27

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

Question 28

What are ESKAPE pathogens?

Answer 28

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

Question 29

What does Enterococus faecium cause?

Answer 29

Blood infection UTIs

Question 30

What is VRE and how does it work?

Answer 30

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

Question 31

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

Answer 31

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

Question 32

What are some examples of ESKAPE pathogens?

Answer 32

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

Question 33

What is beta-lactamase?

Answer 33

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

Question 34

How do beta-lactamases inactivate penicillin?

Answer 34

By digestion