Misc. antibiotics Flashcards
What is the MOA of tetracyclines?
REVERSIBLY binds to the 30S ribosomal subunit (inhibits protein synthesis - no binding of tRNA to acceptor site)
Tetracyclines ____________ bind to the 30S subunit while aminoglycosides _______________ bind to the 30S subunit
REVERSIBLY
IRREVERSIBLY
Are tetracyclines bacteriocidal or static?
STATIC (cidal at high concentrations against susceptible organisms)
What are 3 big MOR for tetracyclines?
1) efflux pumps
2) ribosomal protection proteins
3) enzymatic inactivation
Do you see cross-resistance at all for tetracyclines?
YES but not for minocycline
Which tetracycline is resistant to the MORs?
tigecycline
Describe the spectrum of activity for tetracyclines
GRAM POS: MSSA, PSSP, bacillus, listeria, nocardia
GRAM NEG: burkholderia pseudomallei, neisseria, H. flu
Aerobes: actinomyces, proprionibacterium
MISC: legionella, chlamydophila, chlamydia, mycoplasma, ureaplasma, rickettsia
What are the miscellaneous bacteria covered by tetracylcine
legionella chlamydophila chlamydia mycoplasma ureaplasma rickettsia
What is a special inclusion and exemption of tigecycline?
INCLUDED: bacteroides
OMISSION: proteus and pseudomonas
True or false: tigecycline has pseudomonas activity
FALSE (big hole in activity)
Why can you not use tigecycline for bacteremias or UTIs?
cannot maintain good levels in the blood and does not concentrate in the bladder
What is the route of admin for tigecycline?
IV
What impairs absorption of tetracyclines?
di and trivalent cations
Where is a big site of distribution of tet?
prostate
What 3 drugs are not eliminated via the kidney? andwhat 2 are?
renal: tetracycline, demeclocycline
non renal: doxy, mino, tige
what do you use tet/glycylcyclines for?
RMSF, CA pneumo, STDs
What is demeclocycline particularly useful for?
SIADH
Name 5 adverse effects of tetracyclines
1) GI (nausea and vomiting)
2) hypersensitivity
3) PHOTOSENSITIVITY (exaggerated sunburn)
4) renal (fanconi-like syndrome with expired tets)
5) PREGNANCY CAT D
What can you get with expired tet?
fanconi like syndrome (renal failure)
What effects do tetracylcines have on pregnancy?
discoloration of teeth and decreased bone growth
What is the MOA of sulfonamides?
INHIBITS dihydropteroate synthetase (so PABA cannot be incorporated into tetrahydropteroic acid)
Are sulfonamides bacteriocidal or static?
STATIC
What is the most common short acting sulfonamide?
sulfamethoxazole
What does Trimethoprim do?
inhibits dihydrofolate reductase
____________ blocks conversion of PABA —> dihydrofolic acid while __________ blocks dihydrofolic acid —-> tetrahydrofolic acid
sulfamethoxazole
trimethoprim
(both result in no purines produced)
Is resistance common to sulfonamides?
YES (structural change of enzyme)
What is the big gram positive and big gram negative bug TMP-SMX targets?
\+ = staph aureus - = stenotrophomonas maltophilia
TMP-SMX is prophylaxis of choice for what bug?
pneumocystis carinii
Where do TMP-SMX get good distribution?
prostate
Where are TMP-SMX eliminated?
liver and kidney - need to adjust dose in patients with CrCl
Name 5 clinical uses for TMP-SMX
1) acute, chronic, or recurrent infections of the urinary tract
2) acute/chronic bacterial prostatitis
3) skin infections due to CA MRSA
4) bacterial sinusitis
5) NOCARDIA
Name 4 adverse effects associated with TMP-SMX
1) leukopenia
2) thrombocytopenia
3) hypersensitivity (rash)
4) crystalluria
also get tubular necrosis and interstitial nephritis
Name 3 drug interactions common of TMP-SMX
1) phenytoin
2) warfarin
3) methotrexate
How is TMP-SMX administered?
oral (single or double strength) or IV
What is the MOA of chloramphenicol?
binds to 50S subunit of 70s ribosome
For which 3 bugs is chloramphenicol bacterioCIDAL (not static) for?
1) H. flu
2) strep pneumo
3) N. meningitidis
What are 3 resistance mechanisms for chloramphenicol?
1) reduced permeability/uptake
2) ribosomal mutation
3) acetyltransferase inactivation
You should decrease chloramphicol dose in what kind of failure?
liver (adjustment not required in renal failure)
Is chloramphenicol used for pseudomonas?
NO
What 4 bugs does chloramphenicol treat?
Ricketssiae
Spirochetes
Chlamydia
Mycoplasma
IN DEVELOPING WORLD
What are the 2 main adverse effects of chloramphenicol?
1) Aplastic anemia
2) Gray baby syndrome
What are the 2 UTI agents?
Nitrofurantoin
Methenamine
Which UTI agent is converted to formaldehyde in acidic pH?
Methenamine
Which UTI agent is used to suppress UTIs and which to treat?
Methenamine –> suppress
Nitrofurantoin –> treat
How are the UTI agents administered?
orally
What are some adverse effects of nitrofurantoin?
GI intolerance
rashes
