Medications

Question 1

How does a bacteria become resistant to penicillin?

Answer 1

Resistance is often due to beta-lactamase, a bacterial enzyme that hydrolyzes and inactivates the beta-lactam ring. The coadministration of a beta-lactamase inhibitor such as tazobactam prevents beta-lactamase producing organisms from inactivating penicillins, which extends their spectrum of activity (broadens the range of microbes that can be treated).

Question 2

Penicillin is used for:

Answer 2

Gram + cocci, N meningitidis, and T pallidum

Question 3

Beta lactamase inhibitors MOA: Examples

Answer 3

Added with use of penicillins to protect destruction from beta lactamases

Clavulanic Acid, Avibactam, Sulbactam, Tazobactam - end in bactam.

Question 4

Aminoglycosides MOA, clinical use:

Answer 4

GNAT: Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin

Aminoglycosides inhibit bacterial protein synthesis and genetic code reading by blocking the 30S ribosomal subunit.

Penicillins are often coadministered with aminoglycosides to aid in their entry into the cell (penicillins disrupt the cell wall, which allow aminoglycosides to penetrate the bacteria).

Associated with nephrotoxicity and ototoxicity (hearing loss)

Use: severe gram NEGATIVE ONLY rod infections (Streptomycin)

Question 5

Buy at 30, ccel at 50

Answer 5

Aminoglycosides, Tetracylines: 30S inhibitor

Chloramphenicol, clindamycin, Erythromycin, Linezolid: 50S inhibitors

Question 6

Tetracycline MOA:

Do NOT take with what?

Contraindicated for what?

Use for what?

Answer 6

Bind to 30S and prevent attachment of aminoacyl-tRNA.

Do NOT take with milk, antacids, or iron containing preparations bc divalents inhibit drugs absorption in the gut

DON’T TAKE WHEN PREGGERS, or else baby will have bone probs.

Use for: Mycoplasma, Rickettsia, Chlamydia, MRSA

Question 7

Macrolides MOA

Answer 7

-THROMYCIN

inhibit protein synthesis by blocking translocation; binds to 23S of 50S subunit

Treat for: atypical penumonias (myco, chalmyd, legion), chalmydia, gram + cocci, B pertussus, strep infections in patients allergic to penicilin
GRAM POSITIVE ONLY

Question 8

Fluoroquinolone:

Answer 8

fluoroquinolone (DNA gyrase inhibitor)

FLOXACIN

-inhibit prokaryotes topoisomerase II (DNA gyrase)

Use for: gram negative rods of GU and GI tracts (psudomonas)

Contraindicated in: PREGNANCY, CHILDREN bc damage to cartilage, prolong QT interval . can cause arthitis in patients over 60 taking prednisone

Question 9

TMP-SMX affects what?

Answer 9

Trimethoprim-sulfamethoxazole affects folic acid synthesis.

Question 10

Jarisch-Herxheimer reaction happens when?

Answer 10

The Jarisch-Herxheimer reaction is an acute inflammatory reaction that occurs within hours of treatment for spirochetal infections (eg, syphilis). The rapid lysis of spirochetes releases inflammatory bacterial lipoproteins into the circulation and causes acute fever, rigors, and myalgias.

Question 11

Rifampin four Rs

Answer 11

Inhibits DNA dependent RNA polymerase

RNA polymerase inhibitor
Ramps up microsomal cytochrome p450
Red/orange body fluid
Rapid resistance if used alone

Rifampin ramps up cyt 450, but rifabutin does not.

Question 12

Isoniazid:

Answer 12

inhibition of mycolic acid synthesis by bacterial peroxidase catalase, KatG

Vitamin B6 stuff

Question 13

Ethambutol

Answer 13

Eyethambutol

inhibition of arabinosyl transferase

Side effect: optic neuropathy

Question 14

Aminoglycoside mechanism of resistance:

Answer 14

bacterial transferase enzymes inactivate the drug by acetylation, phosphorylation, or adenlyation

Question 15

Cephalosporin MOA:

Answer 15

inhibit cell wall synthesis

organisms that ARE NOT covered by ceph. 1-4
LAME

listeria, atypicals (chlamy, mycolasma), MRSA, Enterococci

Question 16

What’s special about 3rd generation cephalosporins?

Answer 16

they cross the blood brain barrier- Certriaxone for meningitis, gonorrhea, disseminated lyme, ceftazidime for pseudomonas

Question 17

Carbapenem MOA

Answer 17

binds to penicillin-binding protein and inhibits cell wall synthesis ; give with cilastatin

broad spectrum; give only when very ill

Question 18

major side effect of amphotericin B

Answer 18

Hypokalemia and hypomagnesemia are common electrolyte disturbances in patients undergoing treatment with amphotericin B and reflect an increase in distal tubular membrane permeability.

Question 19

What’s a common side effect of TMP-SMX, esp in the elderly?

Answer 19

Hyperkalemia is a common adverse effect of trimethoprim-sulfamethoxazole due to the trimethoprim-induced blockade of the sodium channels in the collecting duct, which prevents sodium-potassium exchange and reduces renal excretion of potassium (similar to the action of amiloride). This effect is often magnified in the elderly population, those with renal failure, or those given other potassium-sparing diuretics, ACE inhibitors, or angiotensin receptor blockers.

Question 20

What med is used for ganicyclovir resistant CMV? and what’s the side effect?

Answer 20

Foscarnet is an analog of pyrophosphate that can chelate calcium and promote nephrotoxic renal magnesium wasting. These toxicities can result in hypocalcemia and hypomagnesemia, which can cause seizures.

Question 21

-azoles MOA and adverse?

Answer 21

inhibit fungal ergosterol synthesis by inhibiting cyt P450 enzyme that converts lanosterol to ergosterol

-gynecomastia, liver, QT interval prolongation

Question 22

Metronidazole MOA:

Answer 22

forms toxic free radical metabolites in the bacterial cell that damages DNA, bactericidal; antiprotozoal