9.1 Sulfa Flashcards
Broadly speaking, what is the mechanism of sulfa drugs?
Prevent folate synthesis- which is necessary for nuclei acid production
What are the 2 mechanisms sulfa drugs use?
Sulfamethoxazole mimic PABA –> competitively inhibits DHT synthetase
Trimethoprim (TMP) – analog of dihydrofolate –> DHF reductase
What is the IV sulfa drug?
Trimethroprim – sulfamethoxazole
What are the PO sulfa drugs?
Trimethroprim – sulfamethoxazole (TMP-SMZ)/Bactrim/Septra
Dapsone
Sulfisoxazole/erythromycin (Pediazole)
What G+ coverage do Sulfa drugs have?
Strep
Staph
Listeria
What G+ are NOT covered by Sulfa? Why?
Enterococcus- Can bring in folate from host
What G- coverage do sulfa drugs have?
H. flu
Enterobacteriaceae
What is Dapsone used for?
Leprosy/ mycobacterium leprae
What are the common side effects of Sulfa?
GI effects Fever Rash (including Stevens-Johnson syndrome) Leukopenia Thrombocytopenia Hepatitis Hyperkalemia
What are special risks with Dapsone?
Hemolysis
Methemoglobinemia = decreased ability of RBC to carry O2
What was the first Quinilone?
Nalidixic acid
What G+ coverage does Nalidixic acid have?
Staph aureus
Strep
What G- coverage does Nalidixic acid have?
E. coli
What is the mechanism of Nalidixic acid against G+/G-?
G+: Topoisomerase
G-: DNA gyrase
= both interfere with unwinding of DNA
What are the IV quinolones?
-oxacin
Ciprofloxacin
Levofloxacin
Moxifloxacin
What are the PO quinolones?
-oxacin Ciprofloxacin Levofloxacin Moxifloxacin Gemifloxacin Ofloxacin
How do bacteria become immune to quinilones?
Mutation of topoisomerase IV/gyrase
Overexpression of reflux pumps
What is the spectrum for Quinilones?
G+ = strep, staph G- = H. Flu, Enterobacteriacea, Neisseria Anaerobic = Clostridia, Bacteroids Atypical = Chlamydia, Mycoplasma, Legionella Mycobacteria = TB, MAC, Mycobacterium leprae
What does Cipro cover?
R1 = piperazine – enhance G- activity (similar to PCN)
Covers Pseudomonas
Weak G+ activity – Not to treat Strep Pneumo infection
Many atypical
Some mycobacteria
What does Levofloxacine cover?
2x more potent than ofloxacin Less active against G- than Cipro Covers Pseudomonas More active against G+ than Cipro Ok for strep pneumo including PCN resistant
What is the difference between cipro/levo?
Cipro- more G-, weaker G+, pseudomonas
Levo- More G+, weaker G-
What do Moxifloxin and Gemifloxacin cover?
Enhance activity against strep pneumo including PCN resistant
Atypical
Less active against G- (i.e. pseudomonas)
Good coverage for anaerobes
What populations are quinilones contraindicated with?
Peds
Pregnancy
What are the SA of quinilones?
QT prolongation Achilles rupture \+ risk for C Diff N/V/D, abd pain Headache/dizzy Rash
