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Flashcards in 8.4 Deck (27):
1

What is the mechanism of rifamycins?

Targets RNA polymerase (which is used in transcription) to prevent DNA --> mRNA

2

How do bugs develop resistance to rifamycins?

Mutation, common

3

How are rifampin used?

TB, sometimes as an add-on coverage targeting biofilms
Prophylactically against Neiserria meningitis, and H. flu

4

What are some examples of rifampins? Consequences?

Rifampin- PO, IV induce P450
Rifabutin- PO less P450
Rifapentine- PO, q week for TB
Rifamaxin- PO, for traveller's diarrhea

5

What are the toxicities of rifampin?

N/V/D
Hepatitis
Rashes
Orange/red urine/tears

6

What is the spectrum of rifampin?

My New Strange Friend
Mycobacterium- TB, avian, leprae
Neisseria meningitis
Staph
H. Flu

7

What is the mechanism of aminoglycosides?

AG (+) bings to membrane (-) and makes a transient hole.
Binds to 30s causing mis read

8

Do ahminoglycosides cover aerobes or anaerobes?

Aerobes- the transporter that brings them in requires O2

9

What is the spectrum for ahminoglycosides?

Anaerobic G-
Enterobacteriacea, Pseudomonas, Mycobacterium tuberculosis, or mycobacterium Avium Complex (MAC)

No activity against G+ alone, can use synergistically with other drugs, eg with vanc for endocarditits

10

How do bugs become resistant to aminoglycosides?

More efflux pumps
Ribosomal mutation
** Resistance is not class-wide

11

How are aminoglycosides usually used?

Usually used together with other cell wall acting abx for synergy (i.e. PCN and Vancomycin)
Uptake of AG enhanced by cell wall acting abxs
Use for G+ enterococci even the bacteria is moderately resistant to AG

12

What is streptomycin used for?

IV, oldest, second line for TB

13

What is gentamicin used for?

IV, most commonly use

14

What is tobramycin used for?

IV, cross resistant with gentamicin; No activity against enterococcus

15

What is amikacin used for?

Reserved for resistant cases after tobra/gent therapy failed
No enterococcus coverage

16

What is neomycin used for?

topical cream, ointment, eye drops – not for systemic use due to toxicity
PO – bowel prep – 1gm Q1h x4, 1gm Q4h x 4
Hepatic encephalopathy – (reducing NH3+ level) – 1-3gm Q6h x 5-6days

17

What are the toxicities of aminoglycosides?

Risk factors: elderly and combining with other renal toxic drugs
Ototoxicity – (up to 50% with risk factors)
Auditory impairment – irreversible hearing loss
Vestibular toxicity – disturbances in balance (esp. Streptomycin)
Nephrotoxicity – penetrate proximal renal tubule cells (up to 5-10%)
Usually reversible – return to baseline after drug is d/c’ed
Usually after 4-5 days of therapy

18

What is the mechanism of macrocodes and ketolides?

The macrolides bind reversibly to the 50S subunit inhibit peptidyltransferase prevent forming peptide bonds between the amino acids.

=Target 50s, when binds prevents elongation of protein, stopping protein production

19

How do bugs gain resistance to macrolides/ketolides?

Prevent penetration – bulky size
Efflux
Enz-mediated ribosome site alteration
Mutation of ribosome binding site
Resistance is a class effect

20

What is the spectrum of macrolides/ketolides?

G(+): Strep, Staph,
G(-): Neisseria, H. Flu, Bordetella pertussis,
Atypical: Chlamydia, Mycoplasma, Legionella, Rickettsia, Mycobacterium, Spirochetes (i.e. Treponema, Borrelia)

21

Which macrocodes/ketolides are PO and IV?

Erythromycin
Azithromycin

22

What does erythromycin PO treat?

Intestinal amebiasis, syphillis, gastropheresis

23

What G- exception does erythromycin have?

No H. flu

24

What does the Z-pack treat?

Pharyngitis, Community Acquired PNA, COPD, Chlamydia

25

What is the difference between PO and IV azithromycin?

better penetration with IV

26

What is Clarithromycin (Biaxin) used for?

CAP, MAC proph, and H pilori
CAP = pna

27

What is telithromycin used for?

Community-aquired PNA inpatient