Antibiotic Resistance

Question 1

How do bacteria respond in order to evade the damaging effects of an antibiotic?

Answer 1

They change the conformation of the target enzyme

Question 2

What are three ways bacteria can be resistant to antibiotics?

Answer 2

1. Break apart the antibiotic (cell membrane or cytosol enzymes)
2. Throw the antibiotic out (cell membrane efflux pumps)
3. Modify the antibiotic target (genetic changes to cellular component structure)

Question 3

What do beta lactamase enzymes do and where are they found?

Answer 3

They break the beta lactam ring which makes the drug ineffective they are produced by the bacteria

Question 4

Are beta lactamse enzymes specific to one antibiotic or does a one kill all antibiotics?

Answer 4

They are specific. There are dozens of known beta lactamase enzymes

Question 5

What are some examples of beta lactamase enzymes?

Answer 5

• Penicillinase
• Cephalosporinase
• Carbepenemase
• ESBLs (extended spectrum beta lactamase) these can take out ALL beta lactams making bacteria with this enzyme hard to treat

Question 6

What are some of the most common antibiotic resistance pathogens?

Answer 6

Gram negative rods which synthesize cephalosporinase and carbepenemase enzymes

Question 7

What bacteria confers resistance to almost every type of beta lactam antibiotics?

Answer 7

CRE: Carbepenem Resistant Enterobacteriacae

Question 8

What are beta lactamase inhibitors?

Answer 8

Theses are drugs that can render the beta lactamase enzyme inactive, allowing the antibiotic to work.
-They have minimal antibacterial action

Question 9

What is an example of an antibiotic and beta lactamase inhibitor?

Answer 9

Amoxicillin + clavulanic acid = augmentin

*clavulanic acid is the beta lactamase inhibitor

Question 10

What two penicillins have been coupled to a BL inhibitor?

Answer 10

Ampicillin and piperacillin

Question 11

What makes MRSA resistant?

Answer 11

A transpeptidase protein that does not bind BL

Question 12

What is the difference between MSSA and MRSA?

Answer 12

MSSA = can be killed by an anti-staphylococcal penicillin
MRSA = CANNOT be killed by an anti-staphylococcal penicillin (clindamycin would be a better option)

Question 13

If the transpeptidase is altered such that it will not bind a BL antibiotic, can one treat the infection with a BL-Beta lactamase inhibitor?

Answer 13

NO, because it wouldn’t bind a BL in the first place, it won’t bind one now. A tx option would be to go to a non-beta lactam cell wall inhibitor drug

Question 14

What is the ONLY beta lactam drug that can treat MRSA?

Answer 14

Cephtaroline

Question 15

What are non beta lactam drug options to treat MRSA?

Answer 15

• Clindamycin
• Vancomycin
• Trimethoprim Sulfamethoxazole

Question 16

Why is MRSA resistant to BL drugs?

Answer 16

It is resistant to BL drugs not because of beta lactamase enzymes, but due to having a transpeptidase enzyme which is not bound by the beta lactam structure

• *The bacteria does not break the drug, it alters the target so the drug cannot bind
• *The altered enzyme is known as PBP-2a

Question 17

What is the molecule responsible for macrolide resistance?

Answer 17

Esterase - breaks cyclic ring of a macrolide

Question 18

DONT GIVE Z-PAKS TO HEALTHY INDIVIDUALS WITH……

Answer 18

VIRAL respiratory infections

Question 19

How does vancomycin resistance happen at the cellular level?

Answer 19

• Vancomycin must bind 2 terminal alanine to work
• 2 acquired genes may alter the AA sequence in the cell wall –> if not to 2 alanine molecules –> vancomycin can’t bind
• The organism mutated the binding site for vancomycin = resistance