Lecture 17: Antibiotics 2

Question 1

What are the most commonly prescribed antibiotics?

Answer 1

30% cell wall inhibitors

34% protein synthesis inhibitors

12% DNA synthesis inhibitors

Question 2

Rational behind cell wall inhibitors? How effective?

Answer 2

Bacteria have cell walls
Mammalian cells do not have cell walls

Targeting the synthesis of bacterial cell walls is one of the most widely effective and least toxic antibiotic strategies

Only effective against actively growing bacteria

Question 3

Mechanism of cell wall inhibitors

Answer 3

Blocks last step of bacterial wall synthesis.

Inhibits transpeptidases that form cross-links between peptidoglycan chains that are essential for cell wall integrity.

Causes osmotic pressure on the cells resulting in cell lysis.

Gram positive bacteria produce enzymes called autolysins that break down cell wall.

Without active cell wall synthesis, autolysins can damage cell wall

Question 4

Mechanism of protein synthesis inhibitors

Answer 4

Drug binds to 70S ribosome (50S and 30S subunits), which is bacterial (mammals have 80S ribosomes with 60S and 40S).

Question 5

Mechanism of DNA synthesis inhibitors

Answer 5

Inhibits enzymes required for bacterial DNA synthesis

Bacterial topoisomerase

DNA gyrase

Block synthesis of DNA/RNA and the growth of cells

Only effective against actively growing bacteria (bactericidal)

Question 6

Mechanism of metabolite synthesis inhibitors

Answer 6

Competitive inhibitors of essential metabolites.

Structurally similar to metabolite but does not fulfill its metabolic function within the bacteria

Question 7

When does relief of symptoms occur in patient taking antibiotics

Answer 7

Usually within 48-72 hours of taking medication

Question 8

Duration of antibiotic therapy

Answer 8

Varies

Usually 7-14 days

Longer if tuberculosis (months)

FINISH THE COURSE OF ANTIBIOTICS EVEN IF FEELING BETTER

Question 9

What to tell the patient if they miss a dose of antibiotics

Answer 9

Take the dose as soon as you remember

If it is almost time for the next dose, skip the missed dose, and continue therapy until course of antibiotics is complete

Never double up on medication unless directed by doctor

Question 10

GI side effects of antibiotics - side effects, how to minimize

Answer 10

Normal GI and vaginal flora are disrupted with most oral antibiotics, leading to 4 major side effects:

Nausea, Vomiting, Diarrhea, Yeast infection

These effects may be minimized/prevented by taking antibiotics with food (cheese, peanut butter, yogurt etc)

Question 11

How to know if patient is having allergic reaction to antibiotics

Answer 11

Can be immediate (30-60 min) or delayed (as long as 72 hours)

Symptoms include red skin, hives, itchy eyes.

Anaphylaxis: tightness of throat and chest, reduced BP, organ dysfunction

Question 12

What to do if patient is having allergic reaction to antibiotics

Answer 12

Stop antibiotic and take an antihistamine

If anaphylactic, call 911

Notify all healthcare providers of allergy