Spreading odontogenic infection in a patient with poorly controlled diabetes
Mr K, 58, attends as an emergency at 09:40 with a three-day history of a dull ache in the lower right quadrant that became constant overnight. He has a swollen right cheek, temperature 38.6 °C, trismus limiting opening to 25 mm, and a firm, raised swelling of the right floor of the mouth with the tongue deviated to the left. He is drowsy and has eaten nothing since yesterday. History: type 2 diabetes (HbA1c 8.9%), hypertension, BMI 34. Medicines: metformin 1 g twice daily, empagliflozin 25 mg daily, ramipril 10 mg, atorvastatin 20 mg. Blood pressure 158/92 mmHg, capillary glucose 19.4 mmol/L, eGFR 52 mL/min/1.73 m² recorded last month. The practice has no oxygen cylinder and the nearest oral and maxillofacial unit is 20 minutes away by car.
1. What is your immediate disposition decision for Mr K, and what clinical features drive it?
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Decision: emergency referral now, not an in-surgery extraction or a prescription-and-home plan.
Features that make this a spreading, potentially life-threatening infection rather than a localised abscess:
- Raised, firm floor of the mouth with tongue deviation - submandibular/floor-of-mouth space involvement; the airway is the concern, not the tooth.
- Trismus 25 mm - spread into the medial pterygoid/masticator region.
- Systemic upset: fever 38.6 °C, drowsiness, nil oral intake, glucose 19.4 mmol/L.
- Host compromise: HbA1c 8.9% and eGFR 52 impair immune response and wound healing.
Action sequence: airway and swallow check; record NEWS-type observations; phone the OMFS unit and describe the floor-of-mouth swelling, trismus and glucose explicitly so they can prioritise; arrange urgent transport (ambulance if any airway or conscious-level concern - drowsiness alone justifies this); send a written summary of medicines and eGFR. Do not attempt incision or extraction in a practice without airway support. Antibiotics are an adjunct to drainage, never a substitute for it.
2. If antibiotics are to be started before transfer, which agent(s) and dose would you choose, and which of Mr K's regular medicines need action?
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Antibiotic (check local formulary): amoxicillin 500 mg 8-hourly as first line; add metronidazole 400 mg 8-hourly because the infection is severe and likely anaerobic-rich. Penicillin allergy → clarithromycin 500 mg 12-hourly. Avoid clindamycin as a routine first alternative (C. difficile risk).
Medicine actions - this is the higher-yield part of the question:
- Empagliflozin: withhold. SGLT2 inhibitors cause glycosuria and volume depletion and are associated with euglycaemic DKA during acute illness - glucose 19.4 mmol/L with reduced intake is exactly the scenario. Advise the receiving team and the patient explicitly.
- Metformin: withhold during the acute illness (sick-day rule) because of dehydration/AKI risk with an eGFR already of 52; restart only after renal function is confirmed.
- Ramipril + a NSAID would be a triple-hit nephrotoxicity risk - avoid NSAIDs for analgesia; paracetamol instead.
- Flag that hyperglycaemia itself worsens infection control; the receiving team should manage the diabetes, not the dental team.
All of this must be documented and handed over in writing, not just said at the door.
3. Six weeks later Mr K is well and asks why he became so unwell 'from a tooth'. How would you explain the link between his diabetes and the infection, and what would you build into his ongoing care?
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Explanation (plain language, non-blaming): high blood glucose impairs neutrophil function and healing and favours bacterial growth, so a dental infection spreads faster and responds more slowly; in return, infection raises blood glucose and can precipitate a hyperglycaemic crisis. It is a two-way relationship, not a moral failing.
Ongoing care plan:
- Prevention focus - the priority is eliminating active disease and preventing recurrence: complete caries treatment, periodontal assessment (diabetes and periodontitis are bidirectionally linked), and diet/fluoride advice.
- Risk-based recall - short interval (3 months) until stability, then extend.
- Medical liaison - write to his GP/diabetes team noting the admission and asking for HbA1c review; target reduction substantially improves outcomes.
- Sick-day and emergency plan - written instructions on who to call, and a note that any facial swelling with trismus or floor-of-mouth involvement is an emergency, not a 'wait and see'.
- Record the counselling and confirm he can restate the red flags (teach-back), since comprehension, not information-giving, is what changes behaviour.