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Describe the differences in bacterial spectrum among 1st, 2nd, and 3rd generation cephalosporins
- 1st gen cephs: only gram + aerobes (but best at this category!)
- 2nd gen cephs: WHAT WE'LL PRESCRIBE: effective against GRAM + AEROBES, gram + anaerobes, and GRAM - ANAEROBES (best anaerobe coverage)
- 3rd gen cephs: pretty much useless- oral agents provide NO effectiveness against anaerobes. May treat gram + aerobes
Explain why erythromycin causes so mush GI upset compared to newer macrolides
ERYTHROMYCIN causes gastrointestinal upset because it causes GUT MOTILITY (clarithromycin does a little and azithromycin causes none). Mechanism = motilin receptor agonist in the gut and gallbladder. (Erythromycin is being studied for use as a prokinetic.)
Explain advantages of clarithromycin over azithromycin.
- Clarithromycin has not been overused compared to azithromycin (z-pack)
- CLARITHROMYCIN retains ACTIVITY AGAINST VIRIDANS GROUP STREP and ANAEROBES (what we need to target in dental infection!)
Explain disadvantages of clarithromycin over azithromycin
- clarithromycin inhibits CYP 3A4, so there are more drug interactions than with azithromycin
- clarithromycin has a bad taste
Identify 6 major drug interactions with macrolides (will get handout for this)
- 1. Anticoagulants- increased risk of bleeding disorders. Monitor pt.
- 2. Bromocriptine- increase in bromocriptine toxicity. Consult physician
- 3. Carbamazapine- toxic effects. Avoid concurrent use.
- 4. Cyclosporine- increase in renal toxicity. Consult physician
- 5. Diltiazem and verapamil- prolonged QT interval with risk of sudden death. Avoid concurrent use.
- 6. Theophyllines- avoid concurrent use if possible. SBE ok.
Recognize and categorize the 6 orally available fluoroquinolones
- Gatafloxacin- limited use against gram - anaerobes
- Levofloxacin- best fluoroquinolone against gram + aerobes
- Moxafloxacin- limited use against gram -anaerobes
- Sparfloxacin- longest half-life
- Trovafloxacin- use limited to life-threatening conditions due to liver toxicity. Best fluoroquinolone against gram - anaerobes.
Describe adverse effects or contraindications for fluoroquinolones
- Arthropathies: contraindicated for children, adolescents, pregnant or lactating
- CNS stimulation/toxicity
- GI Disturbances
- Black box warning, achiles tendon
List the four requirements for CDIC
- Presence of Clostridia difficile in GI tract
- Altered GI flora
- Presence of Toxin A and B (must have receptors in the gut)
- Predisposing factors
List the 5 risk factors for CDIC
- Recent hospitalization
- Recent broad-spectrum antibiotic use
- History of Colitis
- Advanced age
- Recent instrumentation of the lower bowel
List signs and symptoms of CDIC
- Profuse, watery diarrhea 1-20 times/day
- Bloody diarrhea in 5-10% of cases
- Foul smelling
- Abdominal cramping
List five drug interactions w/ metronidiazole