Dental infections Flashcards
1
Q
Metronidazole
Common indications
A
- Antibiotic-associated colitis caused by C.diff, which is a G+ve anaerobe
- Oral infections (such as a dental abscess) or Aspiration pneumonia caused by G-ve anaerobes from the mouth
- Surgical and gynaecological infections caused by G-ve anaerobes from the colon e.g. Bacteroides fragilis
- Also effective for the treatment of protozoal infections including trichomonal vaginal infection, amoebic dysentery, giardiasis
2
Q
Metronidazole
MOA
A
- Metronidazole enters bacterial cells by passive diffusion
- In anaerobic bacteria, reduction of metronidazole generates a nitroso free radical
- This binds to DNA, reducing the synthesis and causing widespread damage, DNA degradation and cell death
- As aerobic bacteria are not able to reduce metronidazole in this manner, the spectrum of action of metronidazole is restricted to anaerobic bacteria (and protozoa)
- Bacterial resistance to metronidazole is generally low but is increasing in prevalence
- Mechanisms include reduced uptake of metronidazole and reduced generation of nitroso free radical
3
Q
Metronidazole
Adverse effects
A
- As with many antibiotics, metronidazole can cause GI upset (such as N&V) and immediate and delayed hypersensitivity reactions
- When used at high doses or for a prolonged course, metronidazole can cause neurological adverse effects including: Peripheral and optic neuropathy, seizures and encephalopathy
4
Q
Metronidazole
Warnings
A
- Metronidazole is metabolised by P450 enzymes, so doses should be reduced in those with severe liver disease
- Metronidazole inhibits the enzymes acetaldehyde dehydrogenase, which is responsible for clearing the intermediate alcohol metabolite acetaldehyde from the body
- Alcohol shouldn’t be drunk- N&V, flushing and headaches
5
Q
Metronidazole
Interactions
A
- Metronidazole has some CYP inhibitory effect- should not be used with warfarin or phenytoin
- Shouldn’t be used with inducers as it reduces plasma concentrations and impairs antimicrobial efficacy
- Metronidazole also increases the risk of toxicity with lithium
6
Q
Metronidazole
communication
A
- Explain that the aim of treatment is to get rid of infection and improve symptoms.
- For oral treatment, encourage the patient to complete the prescribed course. Before prescribing, always check with your patient personally or get collateral history to ensure that they have no allergy to metronidazole.
- Warn the patient not to take alcohol during or for 48 hours after treatment, explaining that if they do they may feel very unwell with nausea, vomiting, flushing and headache.
- If an allergy develops during treatment, give the patient written and verbal advice not to take this antibiotic in the future and make sure that the allergy is clearly documented in their medical records.
7
Q
Metronidazole
Monitoring
A
- Check infection resolves by reviewing symptoms and blood tests
- For treatments that last more than 10 days, measure FBC and LFTs to monitor for adverse effects
