13.1 Antimicrobials & Antibiotic Stewardship
Key Takeaways
- Antimicrobials are an adjunct to, not a substitute for, source control — drainage and debridement of the dental cause remain the primary treatment of odontogenic infection.
- First-line for an acute spreading dento-alveolar infection is amoxicillin 500 mg three times daily; metronidazole 400 mg three times daily is added or substituted for anaerobic or severe infection, or penicillin allergy.
- SDCEP advises a 3-day course when source control has been achieved and a 5-day course otherwise, with review at 48–72 hours; the shortest effective course reduces resistance selection pressure.
- Antibiotic prophylaxis against infective endocarditis is NOT recommended for dental procedures (NICE CG64); give antibiotics only if there is infection at the surgical site.
- Dentistry should use WHO AWaRe 'Access' antibiotics (amoxicillin, metronidazole); narrow-spectrum, short courses are the stewardship standard.
Why Antimicrobial Stewardship Matters
Dentists prescribe a significant share of community antibiotics, and inappropriate prescribing directly drives antimicrobial resistance — one of the greatest threats to modern healthcare. The FGDP/SDCEP Antimicrobial Prescribing for Dental Practice (3rd edition, 2020) and the Antimicrobial Prescribing Self-Assessment Framework set the UK standard: prescribe only when there is a clear clinical indication, use the narrowest effective agent for the shortest effective time, and always combine the drug with operative treatment of the cause.
The core principle is source control. A draining abscess, a necrotic pulp, or a pericoronitis pocket will not resolve with antibiotics alone; the infection must be drained, the tooth extirpated or extracted, or the pocket irrigated. Antibiotics are an adjunct, not a substitute.
When to Prescribe — Indications
| Indication | Action |
|---|---|
| Localised infection, no systemic signs, source controllable | Operative treatment only; NO antibiotics |
| Spreading infection (cellulitis, swelling beyond the vestibule, lymphadenopathy, trismus) | Operative treatment + antibiotics |
| Systemic involvement (fever, malaise, tachycardia) | Operative treatment + antibiotics; consider referral |
| Immunocompromised / high-risk medical patient | Lower threshold; consult physician |
| Surgical site prophylaxis | Not routine; only specific defined high-risk circumstances |
| Infective endocarditis prophylaxis | NOT recommended for dental procedures (NICE CG64) |
A localised abscess with a draining sinus and no systemic features is the classic 'do NOT prescribe' stem.
First-Line Agents, Doses & Duration
The UK first-line regimen for acute dento-alveolar infection:
| Clinical situation | Drug | Adult dose | Duration |
|---|---|---|---|
| First-line | Amoxicillin | 500 mg tds (up to 1 g tds if severe) | 3 days with review; up to 5 days if severe |
| Penicillin allergy or anaerobic/severe | Metronidazole | 400 mg tds | 3 days with review; up to 5 days |
| Severe penicillin allergy (anaphylaxis, angioedema, urticaria) | Clindamycin | 300 mg qds | 5 days |
| Macrolide alternative | Clarithromycin | 250–500 mg bd | 5 days |
SDCEP key point: send a 3-day quantity for amoxicillin or metronidazole when source control is achieved and review at 3 days; stop if systemic signs have resolved. Prolonging courses after resolution increases resistance selection pressure.
Penicillin Allergy — Grade Matters
- Non-severe allergy (vague history, gastrointestinal upset): metronidazole is the usual alternative.
- Severe allergy (anaphylaxis, angioedema, immediate urticaria): avoid all beta-lactams; use clindamycin 300 mg qds. Warn the patient to stop and seek advice if diarrhoea develops (Clostridioides difficile risk).
Metronidazole Cautions
- Alcohol interaction: a disulfiram-type reaction (nausea, vomiting, flushing, headache) — avoid alcohol during the course and for 48 hours afterwards.
- Warfarin: metronidazole potentiates warfarin and is contraindicated (see Section 11.2).
- Neurological: prolonged courses risk peripheral neuropathy — another reason to keep courses short.
Antifungals and Antivirals
- Oral candidiasis — topical nystatin suspension (100,000 units/mL, 1 mL qds, hold in mouth) is first-line for mild localised disease; miconazole oral gel is effective but systemically absorbed and must be avoided in patients on warfarin (MHRA warning). Systemic fluconazole 50–100 mg daily for 7–14 days is reserved for resistant, extensive, or immunocompromised cases.
- Primary herpetic gingivostomatitis — aciclovir 200 mg five times daily for 5 days if started within 72 hours, especially in severe or immunocompromised cases; otherwise supportive care.
- Varicella zoster of the trigeminal dermatome — systemic aciclovir 800 mg five times daily for 7 days, started within 72 hours of rash onset.
Severe, recurrent, or refractory oral candidiasis or HSV should prompt consideration of immunocompromise.
Stewardship in Practice — the AWaRe Classification
The WHO AWaRe (Access / Watch / Reserve) classification groups antibiotics by stewardship concern:
| Group | Definition | Dental relevance |
|---|---|---|
| Access | First-line narrow-spectrum agents with low resistance potential | Amoxicillin, metronidazole — dentistry should stay here |
| Watch | Higher resistance potential; should be targeted | Clarithromycin, co-amoxiclav — not routine first-line |
| Reserve | Last-resort agents for multidrug-resistant infections | Not used in routine dental practice |
Common Pitfalls
- Prescribing for an uncomplicated apical abscess with a draining sinus (source-control the tooth — antibiotics will not help).
- Prolonged 7-day courses when 3 days suffice.
- Using co-amoxiclav as first-line (promotes resistance; reserve for failure of first-line).
- Confusing the NICE 'no prophylaxis' position with older American Heart Association guidance that still recommends prophylaxis in selected high-risk groups.
Condition-Specific Prescribing
The site and severity of infection dictate whether antibiotics have any role at all. For several classic MFDS stems, operative source control is the primary treatment, and antibiotics are reserved for spreading or systemic features.
| Condition | Primary management | Antibiotic if indicated |
|---|---|---|
| Pericoronitis | Local irrigation under the operculum, warm saline rinses, and consider operculectomy or extraction of the opposing tooth if it is traumatising the soft tissue | Metronidazole 400 mg tds only if spreading infection, systemic signs, or severe trismus; amoxicillin is not first-line |
| Acute necrotising ulcerative gingivitis (ANUG) | Meticulous oral hygiene, debridement of necrotic tissue, chlorhexidine mouthwash, and smoking cessation | Metronidazole 400 mg tds for 3 days — amoxicillin is NOT first-line because ANUG is an anaerobic spirochaetal infection |
| Periodontal abscess | Drainage through the pocket, subgingival debridement, and irrigation | Antibiotics only if spreading infection, systemic features, or immunocompromise |
| Ludwig's angina | Medical emergency — urgent hospital referral, airway protection, and surgical drainage in theatre | IV co-amoxiclav + metronidazole (or amoxicillin + metronidazole); clindamycin if penicillin-allergic |
Clinical Governance — Auditing Your Prescribing
The Antimicrobial Prescribing Self-Assessment Framework is a clinical governance tool that asks the practitioner to audit a sample of prescriptions against the SDCEP standard. Each case is checked for a recorded indication, the correct drug, dose, and duration, and a documented review at 48–72 hours. Repeated cycles track whether prescribing improves over time — audit is the mechanism by which stewardship is delivered and demonstrated, not merely aspired to.
Why the 3-Day Review Matters
Reviewing the patient at 3 days stops the course the moment systemic signs resolve, cutting unnecessary exposure and the resistance selection pressure that follows every unnecessary day of antibiotic.
A 35-year-old has a tender, fluctuant swelling buccal to a non-vital lower first molar but no fever or malaise. What is the most appropriate management?
A 24-year-old with a prosthetic aortic valve attends for a routine scale and polish. He is systemically well with no current dental infection. According to current UK guidance, what antibiotic prophylaxis against infective endocarditis is indicated?
A patient is prescribed metronidazole 400 mg tds for acute necrotising ulcerative gingivitis. Which counselling point is essential?
Which antibiotic used in UK dental practice falls within the WHO AWaRe 'Access' group, making it an appropriate stewardship choice for acute dento-alveolar infection?