Exam 8: Fluoroquinolones Flashcards
What are 3 common fluoroquinolone formulations? What generation is each?
Ciprofloxacin (2nd)
Levofloxacin (3rd)
Moxifloxacin (4th)
What is the mechanism of fluoroquinolones?
They target DNA gyrate (Gram negatives) and DNA Topoisomerase IV (Gram positives)
Humans don’t have Gyrase, but we do have a Topoisomerase (II) that could be affected at SUPER high concentrations
Are fluoroquinolones -cidal or -static?
Bactericidal
What is an advantage of each generation of fluoroquinolones?
2nd- Good for systemic infections, Pseudomonas
3rd- Good against Strep and atypicals
4th- Good against anaerobes, gram positive and negative aerobes
What causes antibiotic resistance to fluoroquinolones?
- Plasmid encoded Quinolone resistance proteins (Qnr) shield enzymes from drug
- Plasmid encoded Efflux pumps
- Chromosomal mutations that modify quinolone binding sites
What is an important principle about Fluoroquinolone resistance?
If a bug is resistant to one fluoroquinolone, it’s probably resistant to all of them
What resistance mechanism do aminoglycosides share with Ciprofloxacin?
Plasmid encoded aminoglycoside acetyltransferase can modify Cipro too…
What can inhibit absorption of fluoroquinolones?
Polyvalent ions (Calcium , zinc, iron, aluminum)
What can’t moxifloxacin treat?
UTI because it is metabolized by the liver, not found in urine
What are 3 “respiratory fluoroquinolones”?
Levofloxacin
Moxifloxacin
Gemifloxacin
What bugs can respiratory fluoroquinolones cover?
Strep pneumo
Staph aureus (not if it’s Oxacillin resistant)
Mycoplasma pneumoniae
Legionella pneumophila
fluoroquinolones are the only orally administered antibiotics that are effective against ________? In whom are they useful?
Pseudomonas
Good for managing Pseudomonas in CF patients
How should fluoroquinolones be used in treating Pseudomonas? Why?
For acute exacerbations, not for chronic therapy.
We don’t want to cause resistance.
Which fluoroquinolone can’t treat UTIs?
Moxifloxacin
What are 3 GU infections that fluoroquinolones can treat? What don’t we use them to treat?
UTIs
Prostatitis
Chlamydia
NOT for syphilis or N. gonorrhoeae
Why can’t we use fluoroquinolones for gonorrhea anymore?
Resistance became a big problem
What are 3 GI infections we can treat with fluoroquinolones?
Traveler’s diarrhea
Shigella
Salmonella
What is a consideration when treating traveler’s diarrhea?
Be careful, because fluoroquinolones can induce expression of Shiga-like toxin
Why are fluoroquinolones good for soft tissue infections? What is a soft tissue infection that they shouldn’t be used to treat?
Really good tissue penetration
Osteomyelitis, joint infections, diabetic ulcers.
They should NOT be used to treat MRSA (resistance could be bad)
When would you use fluoroquinolones to treat TB?
MDR TB or TB in HIV patients
What is a rare use of flourquinolones? Which one is used?
Anthrax (Bacillus anthracis)
Ciprofloxacin
A terrorist sprays your patient in the face with some weird powder, but you don’t know what it is. Treatment?
Ciprofloxacin
Treatment for anthrax
What is the most common side effect of fluoroquinolones?
Nausea, GI distress
What is a serious side effect of fluoroquinolones?
C diff.
Heavy fluoroquinolone use probably selected for toxic strains of Clostridium difficile
What is a CNS side effect of fluoroquinolones?
GABA-A antagonism
Increased use of seizure
What is the black box warning for fluoroquinolones?
Chondrotoxicity
Makes people prone to tendon rupture (Achilles)
In whom are fluoroquinolones contraindicated? Why?
Pregnant women (damage bones/joints of the fetus) Children Arthropathy was observed in animal models (chondrotoxicity) Maybe no real danger in the long term though
What are 3 adverse effects of fluoroquinolones?
C diff
Seizures (GABA antagonism)
Chondrotoxicity
Who are most prone to the chondrotoxicity effects of fluoroquinolones?
Old patients
People on corticosteroids
Solid organ transplant patients
What increases the risk of seizures associated with fluoroquinolones.
NSAID use
