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Infectious Disease > Protein Synthesis Inhibitors > Flashcards

Protein Synthesis Inhibitors Flashcards

1
Q

What is the most common bug responsible for community acquired pneumonia?

atypical?

A

CAP- strep pneumo

atypical- mycoplasma

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2
Q

What was methicillin made for?

What makes MRSA so interesting?

A

Methicillin was made to kill bugs resistant to beta lactams (beta lactamase doesn’t hurt methicillin)

It is interesting because MRSA is resistant to methicillin which typically works against resistant bugs!

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3
Q

Why is mycoplasma pneumoniae resistant to penicillins and cephalosporins?

A

Because it lacks a peptidoglycan wall!

-these drug inhibit cell wall synthesis, no wall, no effect

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4
Q

Where do protein synthesis inhibitors exert their antimicrobial effects?

A

By targeting the bacterial ribosome within the cell, not the cell wall

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5
Q

Buy AT 30s

CELL at 50s

A

Aminoglycosides-change shape of 30s subunit–> mRNA read incorrectly
Tetracycline- binds to 30s subunit and prevents attachment of tRNA molecule to mRNA

Chloramphenicol- binds to 50s subunit and inhibits formation of polypeptide bond when making polypeptide chain
Erythromycin- binds to 50s subunit and stops ribosome movement along mRNA (can’t read info on mRNA chain)
Lincomycin- 50s
cLindamycin-50s

*all lead to protein synthesis inhibition

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6
Q

Adverse Effects of Tetracyclines

A
  • deposition in bone and dentition
  • stained teeth and stunted bone growth
  • gastric discomfort; controlled if taken with food other then dairy
  • phototoxicity (severe sunburn)
  • ototoxicity (dizziness, N/V)
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7
Q

Tetracycline Resistance

A

resistant to one tetracycline=resistant to all.

-bug decreases influx pump of abx and develops efflux pump to eject abx out of cell.

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8
Q

Absorption of Tetracycline

-Doxycycline

A

adequetly but not completely absorbed after oral ingestion. Dairy decreases absorption, can cross placental barrier and concentrate in fetal bone and dentition

Doxycycline- can eat dairy with the med, otherwise same absorption as tetracycline.

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9
Q

Distribution:

  • Tetracycline
  • Doxycycline
A

conc. in liver kidney spleen skin and tissues undergoing calcification (teeth & bones).

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10
Q

Excretion of Tetracycline and Doxycycline

A
  • Tetra: released in bile, reabsorbed from intestines to be excreted by the kidneys
  • Doxy: released in bile and excreted by the feces.
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11
Q

CI of Tetracycline

A
  • *pregnant women
  • *breast-feeding
  • *Children under 8 yo
  • Caution if impaired renal function (except doxycycline)
  • Caution if impaired liver function
  • Caution in SLE
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12
Q

Routes of Administration of Tetracyclines

A

Oral
IV
IM– not recommended d/t pain and inflamm.

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13
Q

What are tetracyclines especially useful for? What are they NEVER used for?

A
  • useful in STIs, atypical pneumonia, exacerbations of chronic bronchitis, acne vulgaris,
  • NEVER use for skin infections b/c of decreased activity against staph aureus.
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14
Q

What is the drug of choice for mycoplasma pneum. and chlamydiae, rickettsiae (rocky mtn spotted fever), and lyme disease

A

DOXYCYCLINE!!!

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15
Q

What is the drug of choice for acne vulgaris but rarely used for anything else?

A

Minocycline

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16
Q

What is used in the tx of Syndrome of Inappropriate Anti-diuretic hormone?

A

-Demeclocycline b/c of its inhibiting action of ADH

17
Q

What is the most common macrolide?

A

-Azithromycin

18
Q

MOA of Macrolides?

A

bind irreversibly to a site on 50S subunit or bacterial ribosome inhibiting translocation steps of protein synthesis.

19
Q

Macrolide Erythromycin is effective against the same organisms as Penicillin G, why would we choose this drug over a penicillin?

A

-use this w/ penicillin allergy.

20
Q

Macrolide Resistance

A
  • most strains of staphlyococci in hospitals most are resistant to erythromycin
  • Clarithromycin and azithromycin show cross resistance w/ erythromycin
21
Q

Macrolid Resistance Mechanism

A
  • alteration in binding site of ribosome
  • manifestation of efflux pump to get drug out of cell
  • enzymatic inactivation
22
Q

Macrolide Absorption, DIstribution, Metabolism, and Excretion

A

Erythromicin Absorption

  • destroyed by gastic acid, needs enteric coat.
  • adequately absorbed orally
  • Clarithromycin and Azithromycin Absorption
  • stable in stomach acid and readily absorbed

Distribution for All:
-widely distributed in tissues except CSF.

Metab:
Erythro: cytochrome P450, metabolized in liver.
Clarithromycin metabolized in liver
Azithromycin: doesnt have many interaction w/ other meds.

Excretion:
Erythro & Azithro: concentrated in bile
Clarithro: kidney as well as liver (dose needs to be adjusted in renal pt)

23
Q

Adverse Effects of Macrolides

A
  • GI distress including diarrhea, especially in erythro*** leading to poor pt compliance. Azithro and Claritho are very well tolerated (no GI upset)
  • Ototoxicity- transient deafness at high dose
  • Prolonged QT w/ erythro and clarithro (rare)
24
Q

Why is Azithromycin chosen for tx much more often than erythro and clarithro?

A

fewer adverse effects and drug interactions

for most part dont have to worry about adjustment in pt w/ kidney and liver disease

long half life= easy to use and better compliance.

azithromycin tastes good

25
Q

What bacteria specifically would you not treat w/ a macrolide? When would you specifically treat w/ a macrolide?

A
  • staphylococcal disease

- treat w/ chlamydial species and urethritis STIs, good for typical and atypical pneumonia

26
Q

Macrolides are the first line ALTERNATIVE tx for what?

A

-Group A streptococcal pharyngitis (strep throat)

27
Q

why is chloramphenicol rarely used?

A

-because of its high toxicity. use is limited to life-threatening infections in which there are NO alternatives.

28
Q

Absorption of Chloramphenicol?

A
  • completely absorbed orally

- readily enters CSF.

29
Q

Adverse Effects Chloramphenicol

A
  • hemolytic/aplastic anemia
  • Gray Baby syndrome: interferes w/ mitochondrial ribosomes lead to poor feeding, depressed breathing, cardiovascular collapse, cyanosis, and death
  • interfers w/ multiple other drugs
  • optic neuritis
30
Q

Clindimycin Absorption and Distribution

A

Well absorbed orally

Distributes well into all body fluids except for CSF.

31
Q

What is always resistant to clindamycin

A

c-diff, c-diff is normal in gut, if give clindamycin this may cause overgrowth of c-diff which can lead to potentially fatal disease referred to pseudomembranous colitis.

32
Q

SE of Clindimycin

A

diarrhea, nausea, and skin rash

33
Q

Where are most anaerobic bacteria concentrated?

A

-gut flora and female genital tract flora

Infectious Disease (10 decks)

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