Antibacterial Agents (continued) Flashcards
Indications for Sulfasalazine?
prodrug used in UC and RA broken down to 5-ASA (5-aminosalicylic acid) for (UC) and SP (sulfapyridine)
This drug can treat Crohns confined to the colon as well
Trimethoprim and pyrimethamine inhibit what part of folic acid synthesis?
dihydrofolate reductase
Sulfonamides inhibit what part of folic acid synthesis?
dihydropteroate synthetase
Indication for Cotrimoxazole? What is another name for it?
trimethoprim-sulfamethoxazole
DOC nocardia
listeria (backup)
gram negative infections (E. coli, Salmonella, Shigella, H. influenza
Gram-positive infections (staph, including community acquired MRSA, Strep)
Fungus Pneumocycstis jiroveci (back up drugs are pentamidine and atovaquone)
protozoa: toxoplasma gondii (sulfadiazine and pyrimethamine)
What are the S/E of using folic acid inhibitors?
kernicterus in neonates (avoid in third trimester)
What are the S/E of sulfonamides?
HSR (SJS)
Hemolysis in G6PD deficiency
phototoxic
S/E trimethoprim or pyrimethamine.
bone marrow suppression (leukopenia)
What are the direct inhibitors of nucleic acid synthesis drugs?
quinolones
What microbials are useful against bacillus anthraces?
anthrax is treated with quinolones as well as pens and tetracyclines
What is the common suffix of the quinolone family of drugs?
“floxacins”
MOA of quinolones?
are bactericidal and interfere with DNA synthesis
inhibit topoisomerase II (DNA gyrase) and topoisomerase IV (responsible for separation of replicated DNA during cell division_
Indications for use of quinolones?
anthrax
UTI and other gram (-) especially in cases of drug resistance
drug resistant pneumococci( levofloxacin)
What can limit the absorption of quinolones?
iron and calcium
What are the side effects of quinolones?
NEED TO REMEMBER TENDONITIS, tendon rupture, nerve damage
(peripheral neuropathy)
phytotoxicity, rashes
What are quinolones contraindicated in? Why?
pregnancy and in children (inhibition of chondriogenesis)
MOA of metronidazole?
in anaerobes, converted to free radicals by ferredoxin, binds to DNA and other macromolecules and is bactericidal
What spectrum of organisms can metronidazole work against?
antiprotozoal: giardia, trichomonas, entamoeba
antibacterial: strong activity against most anaerobic gram-negative bacterioides species Clostridium species, Gardnerella, and H. pylori
GET BaC on the METro G
Indication for Metronidazole?
pseudomembranous colitis
S/E of using Metronidazole?
metallic taste, disulfiram-like effect
How many months would you use rifampin and isoniazid for prophylactic treatment in the management of mycobacterium tuberculosis?
rifampin (4 months)
isoniazid (9 months)
What type of antibiotics are typically used for H. pylori induced GI ulcers?
clarithromycin and amoxicillin (2 antibiotics) with PPI omeprazole
BMT regimen bismuth, metronidazole, and tetracycline
How can prophylaxis of MAC be treated?
azithromycin or clarithromycin
Other ways besides macros to treat MAC?
clarithromycin + ethambutol + rifabutin (rifampin like drug)
Isoniazid MOA and how an organism may confer resistance to this drug?
inhibits mycolic acid synthesis
prodrug requires conversion by catalase
high level resistance deletions in katG gene (encodes catalase needed for INH bioactivation
S/E INH?
- hepatitis
- peripheral neuritis (use vit. B6)
- sideroblastic anemia (use B6)
- SLE in slow acetylators (rare)
Rifampin MOA?
inhibits DNA - dependent RNA polymerase (nucleic acid synthesis inhibitor)
S/E of rifampin?
hepatitis
red orange metabolites
MOA of Ethambutol?
inhibits synthesis of arabinogalactan (cell-wall component)
S/E of ethambutol?
dose dependent retrobulbar neuritis >visual acuity and red green discrimination
Pyrazinamide S/E?
hepatitis
hyperuricemia
Streptomycin S/E?
deafness
vestibular dysfunction
nephrotoxicity
