Antibiotics That Interfere With Folate Synthesis or Nucleic Acid Processing Flashcards
What step of the bacterial folic acid pathway do sulfonamides stop?
First step
Disruption of the folate pathway is generally ______ in single agent therapy
bacteriostatic
What was the first sulfonamide that is no longer used? Was a pro-drug. worked against staph and strep
Prontosil
What type anitiobitcs are sulfonamides considered on their own?
Bacteriostatic
What bacteria do sulfonamides work against?
Gram positive and negative bacteria
How do bacteria have resistance against sulfonamides?
Additional production of PABA
changes in binding sites from sulfonamides
What are the three sulfonamides used today (oral absorbable)?
Sulfadiazine
Sulfisoxazole
Sulfamethoxazole (+Trimethoprim)
What is the oral, non absorbable sulfonamide?
Sulfasalazine
What is sulfasalazine used for?
Anti-rheumatic (used for RA)
What are 2 topical sulfonamides agents?
Sodium sulfacetamide
Silver sulfadiazine
What topical sulfonamide is used in opthalmic solution or ointment for bacterial conjunctivitis or treatment of chalmydia trachoma?
Sodium sulfacetamide (Sulamyd)
What is a topical sulfonamide used for topical burn infection prophylaxis?
Siver sulfadiazine (Silvadene)
Are sulfas well absorbed?
Yes, excpet sulfasalazine
What sulfa drug is highly protein bound to albumin?
Sulfamethoxazole
What are other protein bound drugs that you should be careful with prescribing sulfamethoxazole with?
Warfarin
Phenytoin
Sulfonylureas
What is the most common AE with sulfonamides?
Photosensitivity (N/V/D, HA)
What is the pregnancy category of silver sulfadizine?
Category B (because it is applied topically)
What is the problem with giving sulfa drugs to pregnant patients?
Neonatal kernicterus
What part of the folic acid pathway does trimethoprim interfere with?
Second part
Are trimethoprim or sulfa drugs more potent?
Trimethoprim
What is the prime indication of sulfa plus trimethoprim?
UTIs
When sulfas are combined with trimethoprim, what type antibiotic does it turn into?
Bactericidal
What sulfa drug is trimethoprim combined with?
Sulfamethoxazole
What is sulfamethoxazole/ trimethoprim the drug of choice for?
Pneumocystis carinii
bacterial diarrhea
prophylaxis for UTI
Periotonitis prevention in patients w/ cirrhosis
Is there a lot of resistance to sulfamethoxazole/ trimethoprim?
Yes
What is sulfamethoxazole/ trimethoprim used for in AIDS patients?
PCP & toxoplasma gondii
What is another name for sulfamethoxazole/ trimethoprim?
Bactrim
What are three drugs that inhibit DNA processing?
Quinolones (same as floroquinolones)
Rifampin
Nitrofuratoin
How do quinolones block bacterial DNA synthesis ?
Inhibit DNA topoisomerases
What bacterias do quinolones act against?
Gram + and gram - bacteria
What type antibiotic are quinolones considered?
Bactericidal
What type bacteria does ciprofloxacin cover?
Really good gram -
lost a lot of gram positive
Levofloxacin and moxifloxacin cover against what bacterias and how well?
Really good gram negative covered
even better gram positive coverage than Cipro
What quinolone class has continued gram negative and gram positive coverage but also covers anaerobic (B. fragilis)
trovafloxacin
What atypical pneumonia organisms do quinolone cover?
CHalymydia penumoniae
mycoplasm pneumoniae
What intracellular pathogens do quinolones cover?
Legionella
Mycobacteria TB
mycobacteria avium complex
what quinolone is indicated for post-exposure prophylaxis for anthrax?
Cipro
What quinolone treats anthrax?
Levofloxacin
What is trovafloxacin restricted to due to severe hepatic toxicity?
FDA restricted to life or limb threatening infections
What should quinolones not be used for in order to avoid increase in resistance?
Upper or lower respiratory infections
Skin/ soft tissue infections
What do the quinolone class end in?
“floxacin”
How are most quinolones excreted?
renally
How is Cipro excreted?
50% renal, 40% bile (still need dose adjustment for renal insufficiency)
What are the most common AE for quinolone?
N/V/D
What are some people who may have seizures with cipro?
little old ladies with renal impairments, on NSAIDs
What are some rare AEs of quinolones?
Seizures
blood dyscarsias
peripheral neuropathy (irreversible)
What is the most common type of interaction with cipro?
CYP interactions
What drugs can cipro interact with?
Antacids
sucralfate
Iron
Multivitamins
What type patients do you want to be worried about tendinitis and tendon rupture on Cipro?
Elderly
Renal failure, glucoccorticoid use
With Cipro, levels of what drugs will be increased due to CYP interactions?
Increased levels of methadone and theophyilline
with glyburide- will get severe levels hypoglycemia
What forms is moxifloxacin avaliable as?
Oral or IV; broad spectrum single dose
What is gemifloxacin used to treat?
mild-moderate CAP due to multi-drug resitsanct Streptococcus pneumoniae
What type antibiotic is metronidazole?
bactericidal
How is metrondiazole avalaible?
Oral
IV
Topical
What is the main type organism that metrondiazole works against?
Anaerobic and protozoan infections
Metrondiazole treats what two GI conditions? (main indications)
C. diff
H. pylori
What trimesters of pregnancy in metrondiazole ok in?
2nd and 3rd (not in first trimester)
What 3 drugs does metrondiazole interact with?
Warfarin (increased INR)
cimetidine (increase metrondiazole levels)
lithium toxicity
What happens when metrondiazole and ETOH?
disulfiram-liek rxn. (flushin, HA< N/V)
What are some side effects with metrondiazole?
N/V/D/ constipation
Darkened urine
Edema (patients w/ heart failure)
transient luekopenia, neutropenia
When is nitrofurantoin bacteriostatic? Bactericidial?
Bacteriostatic in low concentrations
bactericidal in high concnetrations
Nitrofuratoin reaches high concentrations where?
In the urine
What are some side effects with nitrofuratoin?
N/V
interstitial pulmonary fibrosis w/ chronic use
Patients with G6PD deficiency will experience what with nitrofuratoin?
hemolysis
What type antibiotic is polymyxin B?
Bactericidial (leads to lysis)
What type bacteria does plymyxin B work against?
Gram negative (Pseudomonas aeruginosa)
Polymyxin B has high rates of what toxicities, so it is limited to only topical use?
Nephro and neuro toxicity
What is polymyxin B used for (topical)?
gut sterilization
bladder irrigation
ophthalmic
How can polymyxin B be used?
only topically
What is daptomycin used for (what type bacteria)?
Multi-drug resistant gram + bacteria
What are some side effects of daptomycin?
Reversible myopathy, GI
What type antibiotic is daptomycin?
Bactericidal