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61 Cards in this Set

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  • Back
Macrolides are drugs that are ______spectrum antibiotics,
that inhibit bacterial
____________
broad
protein synthesis
their large size
what is the best known and oldest member of the macrolides?
erythromycin
what are the second generation macrolides?
azithormycin and clarithromycin
Telithromycin is what generation of what class?
thrid generation macrolide
what is the mechanism of action of all macrolides?
by inhibiting bacterial protein synthesis
macrolides bind to the bacterial ___________,
blocking protein synthesis—no protein
synthesis = no bacterial replication
50s subunit ribosome
what frequently serves as a great alternative then someone is penicillin allergic?
Why?
the macrolide Erythormycin
Erythromycin has a similar spectrum as PCN
G, great for G+ but more limited G- coverage,
Not similar chemically to PCN and has no
allergic cross-reactivity
what would be a good class of drugs to look at when needing to treat more exotic species of bacteria?
The Macrolides:
Erythromycin
what is an acronym for remembering the macrolides you have to know?
Big Macs
Earn (Erythomycin)
A (Azithromycin)
CLap (Clarithromycin)
what macrolide is great for treating patients with renal failure?
Why?
Erythromycin
because it is eliminated primarily in the liver, with excretion into the bile.
are macrolides good for treating upper respiratory tract infections cause by strep pneumo and strep pyogenes? Why?
Yes, excellent.
because those two orgs are G+ and Macrolides are effective against G+
which of the macrolides is very sensitive to gastric acid degredation?
Erythromycin base
How is the problem erythromycin's acid susceptibility addressed?
This type of erythromycin is known as erythromycin base, frequently given as an enteric-coated tablet, to protect it from stomach acid
Several newer formulations of erythromycin have been
developed, with more stability in stomach acid, and
better bioavailability
• Erythromycin stearate, ethylsuccinate, estolate… these are all
basically erythromycin base, with a specific coating. The
coating dissolves, and all these forms are converted to base in
the small intestine and absorbed
• There is no difference in antibiotic activity, or spectrum
what would you use to treat legionella pneumophila or bortadella pertussis?
macrolides
what would you use to treat diptheria, mycoplasma pneumoniae, or chlamidia?
macrolides
do any of the macrolides inhibit cP450?
Erythromycin and clarithromycin
what are the adverse effects of erythomycin?
1.GI upset: pain, nausea, vomiting, and diarrhea… sometimes these can be reduced by giving with food, but only with the ethylsuccinate, estolate varieities
2.Cholestatic hepatitis, and the estolate formulation: occurs
exclusively in adults
• Symptoms include nausea, vomiting, abdominal pain, jaundice, elevated levels of bilirubin and transaminases
3.Ototoxicity at high doses, but completely reversible when the
drug is stopped
which of the macrolides would you use with another drug that uses cp450 in its metabolism? Why?
Azithromycin/Zithromax
b/c it does not have any cP450 effect.
what is adventageous about azithromycin/Zithromax over the other macrolides?
T1/2 = 68 hours, Z-pack, 6 tablets over 5 days=10 days of tx
people are much more likely to finish their z-pack
what is different btw tne 2nd gen macrolides (azithromycin & clarithromycin) and the 3rd gen Telithromycin/Ketek?
locks protein synthesis at two locations on
the bacterial ribosome.
how do some bacteria resist macrolides?
Some bacteria have demonstrated
resistance to these antibiotics by
altering their ribosomes, so that
erythromycin no longer binds to
ribosomes
what spectrum are macrolides?
Broad Spectrum
what ABT would you use against an atypical infection involving anaerobic organisms?
Clindamycin/Cleocin
what adverse effect is almost always a problem with Clindamycin?
psuedomembranous collitis/ C. diff
clindamycin/cleocin will work against basically the same organisms as what two drugs?
Penicillin and erythromycin
where is Clindamycin/Cleocin metabolized and eliminated?
liver
urinary and billiary elimination
where are the Macrolides metabolized and eliminated?
the liver
principally in the feces
what drug might you see prescribed for a c. diff infection?
metronidazole or oral vcancomycin
what is the mechanism of action of Clindamycin/Cleocin?
inhibits protein sythesis at the level of the 50s ribosome
what spectrum are tetracyclines?
Broad
what is the mechanism of action for tetracyclines?
TCN bind to the 30s subunit of the baterial ribosome, which inhibits protein synthesis.
Are tetracyclines bactericidal or bacteriostatic?
Bacteriostatic?
How do tetracyclines enter the bacterial cell?

How does resistance occur?
TCN cannot cross cell membranes, in bacteria, they must be
taken up by an active transport process, that is particular to
bacterial cells (mammalian cells lack this transport process,
which accounts for the selective toxicity of this drug)
• Resistance is demonstrated by bacteria being able to stop this
active transport uptake of the drug
Tetracyclines are limited by their _______
toxicities
What diseases are tetracyclines very useful for and would be a first choice drug?
Chancroid, Haemophilus ducreyi
• Rabbit fever/tularemia, Francisella tularencis
• Black plague, Yersinia pestis, anthrax, Bacilius anthracis
• Brucellosis, Brucells spp.
• Cholera, Vibrio cholera
• Rocky Mountain Spotted Fever, Rickettsiae spp
• Clyamydia
• Mycoplasma pneumoniae
• Lyme disease, Borrelia burgdorferi,
• Syphilis, Treponema palidium
• Gonorrhea, Neisseria gonorrhea
• Proionesbacterium acnes, common acne
tetracyclines should not be taken with what?
Dairy products
calcium
aluminum
magnesium
iron
who can you not give tetracyclines to?
kids under 8 and pregnant women
what are the first gen tetracyclines?
tetracycline
oxytetracycline
demeclocyline
TOD is First
tetracyclines have good or poor distribution to the cerebrospinal fluid?
poor
tetracyclines are eliminated by the
liver and kidneys
what are the long acting tetracyclines?
doxycycline and minocycline
(DO, RE, MI)
RE (Really Long)
which tetracycline would you use for pts with renal impairrment?
doxycline or minocycline: the long acting tetracylines
tetracyclines are what spectrum?
broad
what would you use to treat rocky mountain spotted fever and typhus fever (rickettsia diseases)
tetracyclines
which two tetracyclines would you never give to pts with kidney disease
tetracycline and demeclocycline
which two tetracyclines should you never give to pregnant women and children under 8
tetracycline and demeclocycline
what is the mechanism of action of sulfamethoxazole?
Folic acid antagonist/inhibition
what are the sulfa-based antibiotics you need to know?
sulfamethoxazole and trimethoprim
what is the mechanism of action of trimethoprim
Folic acid antagonist/inhibition - works at a slightly diff point in the production of folic acid by inhibition of a different enzyme from sulfamethoxazole
what is the spectrum of sulfamethoxazole?
very broad with good G+ and G- coverage, including some oddball: toxoplasmosis , plasmodium, chlamydia
.
.
what is an infection of the upper bladder and kidney called?
Pyelonephritis
what is an infection of the lower bladder called?
cystitis
what are the most common causitive organisms in UTI's
80-90% are caused by E. coli, Klebsiella pheumoniae, proteus mirabilus,
(All of these are Gram -)

10-15% are caused by G+ Staph saprophiticus

oddball anaerobes: bacteriodes, clostridium perifringens, c. diff
what percentage of people with Foley's will contract a UTI
50%
why does being diabetic increase risk for UTI's
sugar spills over into the urine, making for an even better growth medium
Also, WBC's don't work as well in high sugar environment
What is the drug specifically designed for lower UTI's? How does it work
Nitrofurantoin
specifically designed for UTIs because of its ability to concentrate in the urine, not in blood or body tissues.
what are the therapeutic uses of bacteriostatic drugs?
used as second line defense against organisms that are resistant to first line defense drugs.
asymptomatic persons infected with tb will always have a risk that:
latent infection may become active
drug resistance for TB is principally caused by:
inadequate drug therapy:
treatment too short
dosage too low
erratic patient adherance
too few drugs in regimen
infection with a resistant organism any be acquired in two ways:
1. contact with someone who harbors reistant bacteria
2. repeated ineffectual courses of therapy