Micro 12 - Penicillins

Question 1

Which type of Penicillin comes in oral and which one in IV?

Answer 1

Penicillin G : IV form.

Penicillin V : Oral.

Question 2

What are the clinical uses of Penicillin?

Answer 2

1. G(+): S. pneumoniae, S. pyogenes, Actinomyces, Group B Strep.
2. Spirochets: Syphilis.
3. G(+) rods: Clostridium, Listeria, Bacillus.
4. G(-) cocci: Neisseria.

Question 3

What are the toxicities of Penicillin?

Answer 3

1. Hypersensitivity reactions.
2. Hemolytic anemia.
3. Thrombocytopenia.

Question 4

Which are the four penicillinase-resistant penicillins?

Answer 4

Methicillin, Nafcillin, Oxacillin, Dicloxacillin.

Question 5

What is a penicillinase and which type of bacteria have them?

Answer 5

A type of beta-lactamase. Numerous Gram (-) organisms can hydrolyse the beta-lactam ring by bacterial beta-lactamase in periplasm, causing resistance to beta-lactam antibiotics.

Question 6

What are the clinical uses of Penicillinase-resistant penicillins?

Answer 6

S. aureus.

Question 7

When is Methicillin used?

Answer 7

It is used to determine resistant strains of Staph. We do not use it clinically because of toxicity: causes interstitial nephritis.

Question 8

Which one are the aminopenicillins?

Answer 8

Ampicillin and amoxicillin.

Question 9

What are the clinical uses for ampicillin and amoxicillin? Which has a greater oral bioavailability?

Answer 9

They are extended spectrum penicillin.
1. G(+) and G (-); [HEELPSS]:
  Haemophilus influenzae
  E. coli
  Enterococci
  Listeria
  Proteus mirabilis
  Salmonella
  Shigella

So they can be used in UTIs, neonatal infections.

Question 10

What is the mechanism of Penicillin?

Answer 10

1. Bind penicillin-binding proteins: no cell wall synthesis.
2. Inhibit formation of cross-linkages between peptidoglycan chains: weak cell wall.
3. Increase the bacterial production of autolysins, and penicillin may upregulate autolysins: death of bacteria.

Question 11

Which one has greater bioavailability: ampicillin or amoxicillin?

Answer 11

Amoxicillin has greater oral bioavailbility. Ampicillin is used more often as an IV form.

Question 12

What is an interesting side effect of aminopinicillin rash?

Answer 12

Causes generalized rash when given for mononucleosis.

Question 13

What are three beta-lactamase inhibitors?

Answer 13

[Central Standard Time]

1. Clavulanic acid
2. Sulbactam
3. Tazobactam

Question 14

What are some common aminopenicillin and beta-lactamase inhibitor combo, and in what pathology do we use it?

Answer 14

1. Amoxicillin + clavulanic acid: resistant otitis media.

2. Ampicillin + sulbactam (IV): surgical infections.

Question 15

What are three important carboxipenicillin and what is a common name for them?

Answer 15

1. Ticarcillin.
2. Carbenicillin.
3. Piperacillin.

They are sometimes called anti-psudomonal antibiotics.

Question 16

In what organisms do we use carboxipenicillin?

Answer 16

1. Pseudomonas.

2. G(-) rods.

Question 17

Which penicillin drug would you use in syphilis?

Answer 17

Penicillin G.

Question 18

Which penicillin drug would you use in UTI?

Answer 18

Amoxicillin.

Question 19

Which penicillin drug would you use in Pseudomonas?

Answer 19

Ticarcillin, carbenicillin, piperacillin.

Question 20

Which penicillin drug would you use in neonatal infection?

Answer 20

Ampicillin + gentamicin.

Question 21

What organisms can be treated with ampicillin or amoxicillin?

Answer 21

1. URIs: Gram (+) and H. influenza
2. UTIs and colonic infections: E. coli, Proteus, Enterococci, and Salmonella.
3. Neonatal infections: E. coli and Listeria.

Question 22

Which three penicillins can be used to treat Pseudomonas infection?

Answer 22

1. Carbenicillin.
2. Ticarcillin.
3. Piperacillin.

Question 23

What are the two different mechanisms of resistance bacteria use to fight penicillin agents?

Answer 23

1. Beta-lactamases to hydrolyze the beta-lactam rings of penicillins.
2. Alteration of beta-lactam targets, the PBPs (Penicillin Binding Proteins).

Question 24

What is the major cause of bacterial resistance to penicillin?

Answer 24

Beta-lactamase production.