Flashcards in Micro - Antimicrobials (Antimicrobials inhibiting Folate synthesis & DNA) Deck (32):
What are 3 examples of sulfonamides?
(1) Sulfamethoxazole (SMX) (2) Sulfisoxale (3) Sulfadiazine
What is the mechanism of sulfonamides?
Inhibit folate synthesis. Para-aminobenzoic acid (PABA) antimetabolites inhibit dihydropteroate synthase.
Are sulfonamides bacteriostatic or bacteridical?
What is the clinical use for sulfonamides?
Gram-positive, Gram-negative, Nocardia, Chlamydia. Triple sulfas or SMX for simple UTI.
What is the medication for simple UTI?
Triple sulfas or SMX for simple UTI
What are 6 toxicities of sulfonamides?
(1) Hypersensitivity reactions (2) Hemolysis if G6PD deficient (3) Nephrotoxicity (tubulointerstitial nephritis) (4) Photosensitivity (5) Kernicterus in infants (6) Displace other drugs from albumin (e.g., warfarin)
What effect can sulfonamides have on G6PD deficient patients?
Hemolysis if G6PD deficient
What effect can sulfonamides have related to albumin? Give a specific example of this.
Displace other drugs from albumin (e.g., warfarin)
What are 3 mechanisms of resistance against sulfonamides?
(1) Altered enzyme (bacterial dihydropteroate synthase), (2) decreased uptake, or (3) increased PABA synthesis
Draw the folate synthesis pathway from PABA to DNA/RNA/Protein, noting where sulfonamides and trimethoprim/pyrimethamine act.
Pg. 185 in First Aid 2014 for visual at bottom of the page
What is the mechanism of trimethoprim?
Inhibits bacterial dihydrofolate reductase.
Is trimethoprim bacteriostatic or bactericidal?
With what other drug is trimethoprim used in combination, and why? For what is this combination used clinically?
Used in combination with sulfonamides (trimethoprim-sulfamethoxazole [TMP-SMX], causing sequential block of folate synthesis; Combination used for UTIs, Shigella, Salmonella, Pneumocystis jirovecii pneumonia treatment and prophylaxis, toxoplasmosis prophylaxis.
What are 3 toxicities associated with trimethoprim? How may this be alleviated?
(1) Megaloblastic anemia (2) Leukopenia (3) Granulocytopenia; May alleviate with supplemental folic acid; Think: "TMP: Treats Marrow Poorly"
What is are 8 examples of fluoroquinolones?
(1) Ciprofloxacin (2) Norfloxacin (3) Levofloxacin (4) Ofloxacin (5) Sparfloxacin (6) Moxifloxacin (7) Gemifloxacin (8) Enoxacin
What is another drug type that acts similarly to fluoroquinolones? What is a specific example of this type of drug?
Nalidixic acid (a quinolone)
What is the mechanism of fluoroquinolones?
Inhibit DNA gyrase (topoisomerase II) and topoisomerase IV.
Are fluoroquinolones bacteriostatic or bactericidal?
With what must fluoroquinolones not be taken?
Must not be taken with antacids
What is the clinical use for fluoroquinolones?
Gram-negative rods of urinary and GI tracts (including Pseudomonas), Neisseria, some gram-positive organisms
What are the 5 most common toxicities of fluoroquinolones?
(1) GI upset (2) Superinfections (3) Skin rashed (4) Headache (5) Dizziness
Again, what are the 5 most common toxicities of fluoroquinolones? What are 4 less common toxicities of fluoroquinolones?
(1) GI upset (2) Superinfections (3) Skin rashes (4) Headache (5) Dizziness; Less commonly, can cause (1) tendonitis, (2) tendon rupture, (3) leg cramps, and (3) myalgias; Think: "fluoroquinoLONES hurt attachments to your BONES."
What are 3 patient populations in which fluoroquinolones are contraindicated, and why?
Contraindicated in (1) pregnant women, (2) nursing mothers, and (3) children under 18 years old due to possible damage to cartilage.
What cardiovascular toxicity may be caused by some fluoroquinolones?
Some may cause prolonged QT interval
In what 2 patient populations may fluoroquinolones cause tendon rupture?
May cause tendon rupture in people > 60 years old and in patients taking prednisone
What is the mechanism of resistance against fluoroquinolones?
Chromosome-encoded mutation in DNA gyrase, plasmid-mediated resistance, efflux pumps.
What is the mechanism of metronidazole?
Forms free radical toxic metabolites in the bacterial cell that damage DNA.
Is metronidazole bacteriostatic or bactericidal?
What is the clinical use for metronidazole?
Antiprotozoal. Treats Giardia, Entamoeba, Trichomonas, Gardnerella vaginalis, Anaerobes (Bacteroides, C. difficile). Used with a proton pump inhibitor and clarithromycin for "triple therapy" against H. Pylori.; Think: "GET GAP on the Metro with Metronidazole!"
What treats anaerobic infection below the diaphragm versus above the diaphragm?
Metronidazole treats anaerobic infection below the diaphragm versus clindamycin (anaerobic infection above diaphragm)
What drugs are used in "triple therapy" against H. pylori?
Metronidazole used with a proton pump inhibitor and clarithromycin for "triple therapy" against H. pylori