33.5 Antimicrobial Stewardship and First-Line Regimens

Principles of Antimicrobial Stewardship in UK Dentistry

Dental practitioners in the UK generate approximately 8–10% of all primary care antibiotic prescriptions within the National Health Service (NHS). Inappropriate prescribing drives the emergence of multi-drug-resistant pathogens (such as MRSA, carbapenemase-producing Enterobacteriaceae, and vancomycin-resistant enterococci).

The Faculty of General Dental Practice (FGDP UK), the Scottish Dental Clinical Effectiveness Programme (SDCEP), and the National Institute for Health and Care Excellence (NICE) establish clear prescribing principles:

                        Patient Presents with Odontogenic Pain / Swelling
                                                │
                 ┌──────────────────────────────┴──────────────────────────────┐
                 ▼                                                             ▼
   Localized Swelling / Pulpitis                                 Spreading Infection / Systemic Signs
 - Periapical / periodontal abscess                           - Diffuse facial cellulitis
 - Acute irreversible pulpitis                                - Trismus (<20 mm interincisal opening)
 - Localized alveolar osteitis (dry socket)                   - Pyrexia (>38°C), tachycardia, malaise
 - No systemic involvement                                    - Compromised airway or floor of mouth
                 │                                                             │
                 ▼                                                             ▼
    OPERATIVE DENTAL INTERVENTION                                OPERATIVE INTERVENTION + ANTIBIOTICS
 - Pulpectomy / extirpation of root canal                     - Immediate incision & drainage / extirpation
 - Incision & drainage of abscess                             - Prescribe first-line antibacterial regimen
 - Extraction of unsalvageable tooth                          - Review patient in 48–72 hours
 - ANTIBIOTICS ARE STRICTLY NOT INDICATED                     - Refer to OMFS if airway compromised

[!IMPORTANT] Core Prescribing Rules in Dental Practice:

1. Mechanical Debridement is Curative: Antibiotics do not penetrate necrotic pulpal tissue or organized, avascular abscess fluid. They cannot substitute for local operative drainage or extraction.
2. Irreversible Pulpitis: Antibiotics have no analgesic efficacy in pulpitis and must never be prescribed.
3. Periapical Periodontitis: Antibiotics are strictly contraindicated unless there is progressive, spreading infection.
4. Systemic Indications Only: Antibiotics are indicated exclusively when there is evidence of systemic involvement (fever $>38^\circ\text{C}$, regional lymphadenitis, malaise), spreading cellulitis, trismus, dysphagia, or in severely immunocompromised hosts.
5. Shortest Effective Duration: The standard course is up to 5 days; the patient must be reviewed after 48–72 hours and treatment ceased once systemic symptoms resolve.

First-Line Dental Antibacterial Regimens

Odontogenic infections are polymicrobial, mixed aerobic-anaerobic infections dominated by oral viridans group streptococci, Peptostreptococcus, and strict Gram-negative anaerobes (Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum).

Alternatives in Confirmed Penicillin Hypersensitivity

In patients with a verified history of immediate hypersensitivity to beta-lactams (anaphylaxis, angioedema, urticaria):

1. Clarithromycin:
   • Mechanism: Macrolide antibacterial; reversibly binds to the 50S ribosomal subunit, blocking bacterial protein synthesis by inhibiting transpeptidation and translocation.
   • Adult Dose: 250 mg to 500 mg twice daily (bd) for up to 5 days.
   • Drug Interactions: Potent inhibitor of cytochrome CYP3A4 and P-glycoprotein. Interacts with simvastatin/atorvastatin (causing rhabdomyolysis), direct oral anticoagulants (DOACs: apixaban, rivaroxaban), carbamazepine, and prolongs the cardiac QTc interval.
   • Alternatives: Azithromycin (500 mg once daily for 3 days) or Erythromycin (250–500 mg qds).
2. The Clindamycin Warning:
   • Mechanism: Lincosamide; binds to the 50S ribosomal subunit.
   • Clinical Alert: Historically prescribed for penicillin-allergic dental patients, clindamycin is now strongly discouraged in primary dental care by the SDCEP and MHRA. It eradicates the protective commensal gut microflora, predisposing patients to life-threatening pseudomembranous colitis caused by Clostridioides difficile. It should only be initiated under specialist microbiological guidance.

Prophylaxis Versus Treatment

Candidates must separate therapeutic prescribing from prophylaxis, because the rules differ. NICE clinical guideline 64 states that antibiotic prophylaxis against infective endocarditis is not routinely recommended for people undergoing dental procedures, a position that distinguishes UK practice from that of many other countries and is therefore heavily examined for overseas candidates. The guidance allows that for people at increased risk of infective endocarditis, antibiotic prophylaxis may be considered on a case-by-case basis following discussion with the patient and, where appropriate, their cardiologist. Patients at increased risk must be given clear information about the importance of oral health, the symptoms of endocarditis and when to seek advice. Prescribing prophylaxis routinely for a patient with a prosthetic valve before an extraction, without that individualised discussion, is the wrong answer in a UK examination even though it would be correct in many other jurisdictions.

Surgical prophylaxis for other indications — for example before implant placement or complex bone grafting — is a separate, single pre-operative dose decision, and should not be continued as a post-operative course "to prevent infection".

Common Prescribing Errors Examined

Several errors recur in SBA option lists. Prescribing amoxicillin for a dry socket is wrong: alveolar osteitis is not an infection requiring systemic antibiotics, and management is irrigation, debridement, an obtundent dressing and analgesia. Prescribing metronidazole with alcohol risks a disulfiram-like reaction and must be warned about. Prescribing metronidazole to a patient on warfarin without arranging INR monitoring risks a dangerous rise in INR through CYP2C9 inhibition. Prescribing clarithromycin to a patient on simvastatin risks rhabdomyolysis. Prescribing a repeat course because the patient still has symptoms, without re-examining and providing operative treatment, is the archetypal stewardship failure. Finally, the duration matters: UK dental courses are short and are reviewed at 48 to 72 hours, and a seven- or ten-day course prescribed at the outset is an examinable error.

Recording and Governance

Every antimicrobial prescription must be recorded with the indication, the drug, dose, frequency and duration, and the review arrangement. Practices are expected to audit their antimicrobial prescribing against national guidance as part of clinical governance, and dental antimicrobial stewardship toolkits exist for exactly this purpose. Candidates should be able to link the individual prescribing decision to the practice-level audit and to the national problem of antimicrobial resistance.