Necrotising Otitis Externa

In stable patients samples should be obtained before antibiotic initiation

It is essential to include that there is clinical concern about Necrotising Otitis Externa in the clinical details on TRAK/form requests. Theatre samples should be taken to the microbiology lab as a matter of urgency. Yellow paper microbiology request forms can be used instead of TRAK requests, but should be reserved for theatre samples.

1. Blood cultures X 2 sets

2. Deep operative sampling/biopsy specimens:

• • Bacterial culture (Order on TRAK as “C&S – Tissue” and select correct Body/Sample site).
  • Fungal culture (Order on TRAK as “Mycology FUNGI Ix – hair/scraping/tissue).
  • Histopathology (to rule out squamous cell carcinoma).

3. Ear swabs:

• • Bacterial culture (Order on TRAK as “C&S – Swabs” and select specimen type “Swab, ear” (TRAK as routine microbiology).

4. Imaging: (likely to be CT +/- MRI) but needs to be discussed with a named Otologist.

5. Check FBC, U+E’s, LFTs, CRP, HbA1c (if high for diabetic review) and BBV screen.

Urgent ENT review is required and samples should be taken in stable patients before antibiotic initiation

For patient with uncomplicated NOE; Ciprofloxacin 750mg oral every 12 hours should be considered.

Complicated NOE would be manifested by the following:

• Recurrent use of oral/topical ciprofloxacin
• Recurrent NOE
• Central venous thrombosis on MRI or contrast enhanced CT
• Facial nerve or other lower cranial nerve palsy
• Extensive bone involvement , demonstrated by any of the following:
  • CT showing bone erosion in other skull base locations in addition to the external ear canal wall (eg, around stylomastoid foramen, clivus, petrous apex, temporomandibular joint).
  • MRI showing bone marrow oedema extending to central skull-base.
  • CT or MRI showing extensive soft tissue oedema or inflammation or fluid collection below the skull base.
  • Intracranial spread of the disease (eg, dural thickening, extradural or subdural empyema, cerebral/cerebellar abscess).

* For patients with non-severe penicillin allergy, please review for penicillin allergy delabelling

** Avoid fluoroquinolones if taking steroids and in the elderly. Review MHRA Quinolone Warning before prescribing. If an alternative agent is required, please contact Microbiology.

Topical therapy can be used in addition to systemic therapy, until the external auditory canal is cleared.

Discuss with microbiology/infection service and ENT.

Targeted antibiotic treatment is best guided by microbiology results.

Prolonged courses of antibiotics are required (e.g. a minimum of 6 weeks). Long term IV access should be considered (e.g. midline/PICC line). OPAT treatment options should be considered e.g. Piperacillin/Tazobactam via continuous elastomeric infuser or self-administration training.

The decision to stop antibiotics, after a minimum of 6 weeks, should be based on improved otalgia, biochemical markers +/- improvements in imagining. This decision to stop antibiotics should involve a discussion between ENT and Microbiology.

Most common organism is Pseudomonas aeruginosa and other bacteria include Staphylococcus aureus, Enterobacterales, anaerobes and fungal infection (Aspergillus spp. and other fungi).

If Aspergillus spp. is thought to be the causative organism, specialist infection advice is required and this may require prolonged treatment with voriconazole. 

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