Antibacterials - Penicillins

Question 1

What are benefits of using bacterialcidal antibiotics?

Answer 1

Better for immunocompromised patients and difficult to penetrate locations such as meningitis, endocarditis, and bone infections.

Question 2

What does time-dependent killing mechanism mean?

Answer 2

The antibiotics work the best when they are above the MIC for at least 50% of the treatment time for best effects.
– Beta Lactams –

Question 3

How does concentration dependent killing work?

Answer 3

Where the higher the peak concentration from the start of treatment correlates to better treatment due to the drug getting into the bacteria initially and eliciting effects long afterwards.
– Aminoglycosides –

Question 4

How does the killing based upon concentration x time and area under the curve?

Answer 4

The area underneath the curve over a 24 hour period, doesn’t depend on peak dose or time over MIC.
– Quinolones –

Question 5

What are the types of drugs that target the bacterial cell wall?

Answer 5

B-Lactams, Vancomycin, Fosfomycin, and Bacitracin

Question 6

What are unique properties of B-Lactams?

Answer 6

Bactericidal. Most effective on growing bacteria.
Binds PBP, preventing cross-linking of pepidoglycan.
Short Half-Lives

Question 7

What is an intrinsic property of resistance by Gram Negative bacteria?

Answer 7

Outer Cell wall that has porins only allowing in certian molecules that are small enough.

Question 8

How can B-lactamase cause resistance for bacteria and neighboring bacteria?

Answer 8

B-Lactamase is primarily made by gram negative, but also some gram positive bacteria and released extracellularly preventing the concentration gradient of antibiotics from getting too high at the cell and surrounding cells.

Question 9

What kind of dosing is required for B-Lactams?

Answer 9

Time-Dependent, thus more frequent doses to maintain above the MIC.

Question 10

What are unique chacteristics of Penicillins?

Answer 10

Limited CSF penetration, but more can penetrate when inflammation of meningitis.
Short Half Lives
Renal Elimination into urine

Question 11

What drug is primarily used for non-B-lactamase gram positive anaerobic bacteria?

Answer 11

Penicillin G – IV/IM Only

Penicillin V - Oral

Question 12

What is the first line of therapy for syphilis and alternative therapy for lyme disease?

Answer 12

Penicillin G and V

Question 13

What are the three most common modes of resistance to B-lactams?

Answer 13

B-Lactamase
Altered PBP
Porins preventing entry

Question 14

What class of bacteria is Penicillin most effective on?

Answer 14

Streptococcus, not pneumonae though

Works very well on Neisseria Meningiditis

Question 15

What Penicillin would be used for B-lactamase producing Straph Aureas?

Answer 15

Oxacillin

Question 16

What are extended spectrum penicillins that include both gram positive and negative bacterium?

Answer 16

Ampicillin
Amoxicillin
Only if B-lactamase negative

Question 17

What is the drug of choice for Otititis Media for peds?

Answer 17

Amoxicillin

Question 18

What drug is used for Lyme disease if the patient is pregnant or breast feeding?

Answer 18

Amoxicillin

Question 19

What are the differences between Ampicillin and Amoxicillin?

Answer 19

Amoxicillin – better for oral dosing, more absorbed

Ampicillin – IV for meningitis, and PO for GI infections (due to less being absorbed)

Question 20

What penicillins are used for broad spectrum gram negative to treat pseudomonas?

Answer 20

Ticarcillin and Piperacillin

Question 21

What would be used if Pseudomonas was resistant to Ticarcillin?

Answer 21

Piperacillin. Covers Pseudomonas and Klebsiella including organisms resistant to Ticarcillin.

Question 22

What are the most common side effects of Penicillin?

Answer 22

Rash, Diarrhea, Enterocolitis, Fever, Elevated liver enyzmes, hemolytic anemia, and Anaphylaxis

Question 23

What is a problem with taking any type of antibiotics?

Answer 23

They can all cause diarrhea due to killing the natural GI flora increasing chances of enterocolitis and C.Diff

Question 24

How can you predict a pencillin allergy?

Answer 24

PrePen is a skin test used to test for penicillin allergy, which has a 95% accuracy.

Question 25

If you are allergic to one penicillin what does that mean for the rest of the penicillins?

Answer 25

If you are allergic to one, there is a significantly higher chance of being allergic to another.
Less chance with the synthetic penicillins

Question 26

What are the two B-lactamase inhibitors?

Answer 26

Clavulanic Acid
Tazobactam
–Both bind irreversibly to most B-lactamases–

Question 27

What is the benefit of combining B-lactamases with regular penicillins?

Answer 27

This can overcome resistance and successfully rid the bacteria.