Other Antibiotics Flashcards
List of Quinolones
4 listed
- Ciprofloxacin
- Levofloxacin
- Moxifloxacin
- Norfloxacin
Quinolones MOA
Inhibit bacterial topoisomerase enzymes for bacterial DNA synthesis
- DNA gyrase
- induces double-stranded break
- Repairs break
- Topoisomerase IV
- separated daughter chromosomes
- “Decantenation”
Inhibition of these -> DNA damage -> Cell death
Quinolones AKA
Fluoroquinolones if they have a Fluorine attached
Mechanisms of resistance to Quinolones
3 listed
- Alterations of DNA gyrase and/or Topoisomerase IV
- Alterations in cell permeability
- Efflux of drug
Coverage of Quinolones
- Many
- Gpos
- Gneg
- Atypicals
Clinical uses of Quinolones
Adults only
- UTIs (E. coli, other enteric gram negatives)
- Pneumonia (S. pneumo, H. flu, atypicals)
- Abdominal infections (enteric gram negatives)
What is Nalidixic acid and Norfloxacin?
- Not a fluoroquinolones but just a Quinolones because they didn’t have fluorine
- Had mostly Gneg coverage and limited/no Gpos coverage
Ciprofloxacin coverage
- some Gpos coverage
- rarely used for Gpos (resistance)
- very good Gneg coverage
- Most reliable Pseudomonas coverage
Ciprofloxacin Clinical uses
Used in
- UTIs
- GI infections
- Ciprofloxacin ear drops for otitis externa (swimmer’s ear caused by Pseudomonas)
Otitis externa
Swimmer’s ear caused by Pseudomonas
Swimmer’s ear
Otitis externa caused by Pseudomonas
Levofloxacin coverage
More than ciprofloxacin
- Gpos
- Atypicals
- better strep penumo
- covers most Methicillin-susceptible Staph aureus
- Less effective against Pseudomonas than ciprofloxacin
Levofloxacin Clinical uses
Commonly used in Pneumonia (Strep, Atypicals)
Modern quinolones
3 listed
- Gatifloxacin
- Sparfloxacin
- Moxifloxacin
Modern Quinolones coverage
- Better Gpos/Atypical coverage than Levofloxacin
- Less effective for Pseudomonas than Levofloxacin
Modern Quinolones clinical uses
Also used in Pneumonia
Quinolones adverse effects
- GI upset
- Anorexia, NV and abdominal discomfort
- 17% of patients
- Neurologic side effects
- Headache, dizziness
- 2 to 6% of patients
- Very rare but feared: QT prolongation of EKG
- caused by blockade of K+ channels
- can lead to Torsade de pointes
- Tendon rupture/tendonitis
- most commonly achilles
- More common older patients (>60), people on steroids
- Mechanism not well understood
- Cannot use in pregnancy or children
- toxic to developing cartilage in animal studies
Antacids and Quinolones
- Disrupt the absorption of many drugs
- Aluminum and Magnesium hydroxide
- Sucralfate (contains aluminum)
- key drugs
- Tetracycline
- Fluoroquinolones
- Isoniazid
- Iron supplements
Vancomycin MOA
Inhibits peptidoglycan formation (cell wall)
binds D-alanyl-D-alanine peptides and prevents cross linking causing cell wall breakdown > formation -> cell death
Basically same effect as beta-lactams but via a different mechanism
Beta-lactams inhibit transpeptidases (PBPs)
Vancomycin blocks transpeptidase binding
Vancomycin bacterial effect
Bacteriocidal
Mechanisms of resistance to Vancomycin
- Terminal amino acids change
- D-alanyl-D-alanine changed to D-alanyl-D-lactate
- VRSA emerges
VRSA resistance mechanism
- Terminal amino acids change on peptidoglycan D-alanyl-D-alanine changed to D-alanyl-D-lactate
- VRSA emerges
Vancomycin coverage
Gpos only because it is an enormous molecule so it is too large to pass Gneg outer membranes
Vancomycin clinical uses
generally 2 common uses
- Methicillin Resistant Staph Aureus (MRSA)
- Oral therapy for C. diff Pseudomembraneous colitis
Also, often given empirically when MRSA is a concern
- Endocarditis
- Severe pneumonia/sepsis