Penicillins (CWIs)

Question 1

How can we classify penicillins?

Answer 1

We classify penicillins on the basis of antibacterial spectrum,

1. Natural penicillins
2. Antistaphylococcal penicillins
3. Extended-spectrum penicillins
4. Antipseudomonal penicillins

Question 2

Give examples of natural penicillins.

Answer 2

Penicillin G (benzylpenicillin)
Penicillin V

Question 3

Natural penicillins are obtained from the fermentation of fungus __________ ___________

Answer 3

Penicillium chrysogenum

Question 4

What is the antibacterial spectrum of natural penicillins?

Answer 4

Gram-positive and negative cocci
Gram-positive bacilli
Spirochetes

Question 5

__________ (Penicillin G/Penicillin V) is not used to treat bacteremia because of poor oral absorption.

Answer 5

Penicillin V

Question 6

Penicillin ____ (G/V) is more acid-stable and is often employed orally in the treatment of infections.

Answer 6

Penicillin V

Question 7

__________ is the drug of choice in treating gas gangrene and syphilis.

Answer 7

Penicillin

Question 8

What are the examples of Antistaphylococcal penicillins?

Answer 8

Methicillin
Nafcillin
Oxacillin
Dicloxacillin

Question 9

Antistaphylococcal penicillins are __________ resistant penicillins

Answer 9

Beta-lactamase

Question 10

__________ is not used because it causes interstitial nephritis.

Answer 10

Methicillin

Question 11

Penicillinase resistant penicillins have no activity against __________ bacteria

Answer 11

gram-negative

Question 12

________ use is restricted to the tx of infections caused by penicillinase-producing staphylococci, including MSSA

Answer 12

Antistaphylococcal penicillins

Question 13

Potency of penicillin ___ is five times more greater than penicillin ___

Answer 13

Potency of penicillin G is five times more greater than penicillin V

Question 14

Piperacillin has activity against _______________ (bacteria)

Answer 14

Pseudomonas aeruginosa

Question 15

Formulation of piperacillin with _________ extends the antimicrobial spectrum to include penicillinase producing organism

Answer 15

tazobactam

Question 16

What is the mechanism of resistance to penicillins?

Answer 16

B-lactamase production
Decreased permeability
Altered PBPs

Question 17

Gram +ve organisms secrete B-lactamases ___________ (intracellularly/extracellularly)

Answer 17

extracellularly

Question 18

Gram -ve drugs inactivate B-lactam drugs in the _________(cytoplasm/periplasm)

Answer 18

periplasm

Question 19

How do b-lactam antibiotic enter gram -ve bacteria

Answer 19

they have porins

Question 20

Pseudomonas aeruginosa shows resistance by lacking ________ (PBP/porins)

Answer 20

porins

Question 21

How does Klebsiella pneumonia show resistance to B-lactam antibiotic?

Answer 21

K. pneumonia has efflux pumps

Question 22

How does MRSA works?

Answer 22

Modified PBP have a lower affinity for B-lactam antibiotics requiring clinically unattainable concentrations of the drug to effect inhibition of bacterial growth

Question 23

Ampicillin w/ sulbactam is given _______ (IV/IM/orally/IV and IM)

Answer 23

IV and IM

Question 24

Name the B-lactamase resistant penicillins.

Answer 24

Flucloxacillin
Nafcillin
Dicloxacillin
Oxacillin
Methicillin
Cloxacillin

Question 25

Penicillin V is available as ______ (IV/oral) form

Answer 25

oral

Question 26

Piperacillin w/ tazobactam is given ______ (orally/IV/IV and IM)

Answer 26

IV and IM

Question 27

What antistaphylococcal penicillins are administed orally?

Answer 27

Dicloxacillin

Question 28

What antistaphylococcal penicillins are administed IV or IM?

Answer 28

Nafcillin | Oxacillin

Question 29

Procaine penicillin G and benzathine penicillin G are administered _____

Answer 29

IM (depot forms)

Question 30

Food __________ absorption of penicillinase resistant penicillins (dicloxacillin)

Answer 30

decreases

Question 31

Amoxicillin is _________ (acid-stable/acid-sensitive)

Answer 31

acid stable

Question 32

We can take dicloxacillin orally. Is this true?

Answer 32

No. Stomach acid destroyes dicloxacillin

Question 33

Can we take amoxicillin orally?

Answer 33

Yes

Question 34

______ (all/some) penicillins cross the placental barrier

Answer 34

ALL

Question 35

Penicillins penetrate bone and CSF ___________ (easily/hardly/only when tissue is inflammed)

Answer 35

only when tissues are inflammed

Question 36

Pencillins are ________ (good/bad) for prostate infections. | Also give reason why they are good/bad.

Answer 36

bad | penicillin levels are insufficient in the prostate to be effective against infxn

Question 37

What b-lactam antibiotics are metabolised in the liver?

Answer 37

Nafcillin | Oxacillin

Question 38

Which penicillins do not require dose adjustments in renal impairement?

Answer 38

Nafcillin | Oxacillin

Question 39

_________ Inhibits the secretion of penicillins by competing for active tubular secretion via the organic acid transporter hence can increase blood levels

Answer 39

Probenecid

Question 40

Are penicillin excreted in breast milk?

Answer 40

yes

Question 41

What are the adverse reactions of penicillin?

Answer 41

``` Hypersensitivity reactions Diarrhea Nephritis Neurotoxicity Cytopenias ```

Question 42

______ from Clostridium difficile and other organisms may occur with penicillin use

Answer 42

Pseudomembranous colitis

Question 43

The penicillins are irritating to neuronal tissue, and they can cause ________ (dizziness/seizures) if injected intrathecally or if very high blood levels are reached

Answer 43

seizures

Question 44

Epileptic patients are particularly at risk due to the ability of penicillins to cause _________ inhibition

Answer 44

GABAergic

Question 45

__________ (Increased/decreased) coagulation may be observed with high doses of piperacillin and nafcillin if therapy is continued for greater than 2 weeks

Answer 45

Decreased