Antibiotic Resistance

Question 1

What are some intrinsic mechanisms by which antibacterials gain resistance?

Answer 1

Intrinsic mechanisms:
* Impenetrability of antibiotics into the bacterial cell
* Lack of affinity to the antibiotic’s cell target
* Ejection of the drug by chromosomally encoded efflux pumps
* Production of drug-degrading enzymes (ex: beta-lactamase)

Question 2

Some gram-negative organisms like E.coli have become resistant to tetracyclines via the _ mechanism

Answer 2

Some gram-negative organisms like E.coli have become resistant to tetracyclines via the efflux pump mechanism

Question 3

Bacteria can acquire antibiotic resistance genes from other bacteria in one of three ways:

Answer 3

Bacteria can acquire antibiotic resistance genes from other bacteria in one of three ways:
1. Conjugation: mating
2. Transduction: bacteriophage
3. Transformation: competent bacteria

Bacteria can pick up resistance genes horizontally or vertically (across generations)

Question 4

_ is a prophylactic antibiotic given to individuals with rheumatic fever or cellulitis

Answer 4

Penicillin G is a prophylactic antibiotic given to individuals with rheumatic fever or cellulitis

Question 5

_ is a prophylactic antibiotic given to individuals with close contact with meningococcal diseases

Answer 5

Rifampin is a prophylactic antibiotic given to individuals with close contact with meningococcal diseases
* Patients get ceftriaxone

Question 6

_ is a prophylactic antibiotic given to individuals for uncomplicated UTIs and bacterial peritonitis

Answer 6

Trimethoprim-sulfamethoxazole is a prophylactic antibiotic given to individuals for uncomplicated UTIs and bacterial peritonitis

Question 7

_ is a prophylactic antibiotic given to individuals for dog, cat, human bites

Answer 7

Ampicillin-sulbactam and ceftriaxone is a prophylactic antibiotic given to individuals for dog, cat, human bites

Question 8

_ is a prophylactic antibiotic given to individuals before surgery

Answer 8

Cephalosporin is a prophylactic antibiotic given to individuals before surgery (specifically ceftriaxone)

Question 9

blaZ lactamase is the beta-lactamase responsible for S aureus becoming resistant to _ (drug)

Answer 9

blaZ lactamase is the beta-lactamase responsible for S aureus becoming resistant to penicillin
* However, some strains will still be susceptible to derivatives like oxacillin, methicillin

Question 10

MRSA stands for _

Answer 10

MRSA stands for methicillin-resistant S aureus

Question 11

To become resistant to methicillin, S aureus has gained an alteration in _ protein

Answer 11

To become resistant to methicillin, S aureus has gained an alteration in penicillin-binding protein 2a (PBP2a)

Question 12

The gene involved in MRSA is _

Answer 12

The gene involved in MRSA is mecA –> encodes for PBP2a

Question 13

In order to treat MRSA we started using vancomycin in the early 1980s, however, resistant S aureus started popping up that had decreased affinity of vancomycin for the _

Answer 13

In order to treat MRSA we started using vancomycin in the early 1980s, however, resistant S aureus started popping up that had decreased affinity of vancomycin for the binding site (steric hindrance)

Question 14

_ are gram-positive, facultative anaerobic cocci that can cause UTI, biliary tract infection, and subacute endocarditis

Answer 14

Enterococci are gram-positive, facultative anaerobic cocci that can cause UTI, biliary tract infection, and subacute endocarditis

Question 15

Some enterococci have become resistant to vancomycin; these vancomycin-resistant enterococci have gained resistance through _

Answer 15

Some enterococci have become resistant to vancomycin; these vancomycin-resistant enterococci have gained resistance through amino acid modification of D-Ala-D-Ala terminus of the peptidoglycan subunit due to pyruvate hydrogenase

Question 16

The gene assocaited with vancomycin-resistant enterococci is _

Answer 16

The gene assocaited with vancomycin-resistant enterococci is vanH

Question 17

The two drugs that are reserved for treating VRE are _ and _

Answer 17

The two drugs that are reserved for treating VRE are linezolid and tigecycline

Question 18

Multidrug-resistant infections are most often treated with _ or _

Answer 18

Multidrug-resistant infections are most often treated with polymyxins or carbapenems

Question 19

Polymyxins are able to treat multi-drug resistant infections by binding to _ on the cell surface of gram-negative bacteria

Answer 19

Polymyxins are able to treat multi-drug resistant infections by binding to phospholipids on the cell surface of gram-negative bacteria, disrupting the cell membrane

Question 20

_ is an organism that can become multidrug resistant, causing pneumonia, sepsis, ecthyma grangrenosum, UTIs, otitis externa, nosocomial infection, skin infections

Answer 20

P aeruginosa is an organism that can become multidrug resistant, causing pneumonia, sepsis, ecthyma grangrenosum, UTIs, otitis externa, nosocomial infection, skin infections

Question 21

_ , which are used against multi-drug resistant bugs are beta-lactam drugs that have broad spectrum activity against gram-positive cocci and gram-negative rods; they have significant side effects like seizures

Answer 21

Carbapenems , which are used against multi-drug resistant bugs are beta-lactam drugs that have broad spectrum activity against gram-positive cocci and gram-negative rods; they have significant side effects like seizures

Question 22

_ are enzymes that confer resistance to most beta-lactam antibiotics; they are found in gram-negative organisms

Answer 22

Extended-spectrum beta-lactamases are enzymes that confer resistance to most beta-lactam antibiotics; they are found in gram-negative organisms
* Carbapenems are used to treat these