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Otomycosis

Fungal infection of the external auditory canal, usually a superficial colonisation of macerated keratin rather than tissue invasion, accounting for roughly 10 percent of all otitis externa and considerably more in humid tropical settings.

  • Aspergillus species cause 60 to 90 percent of cases, with Aspergillus niger predominant, followed by A. fumigatus and A. flavus.
  • Candida albicans and C. parapsilosis account for most of the remainder and produce a less visually obvious picture.
  • Mixed bacterial and fungal growth is common in previously treated canals.

The canal offers warm humid keratin, an ideal substrate. Disease follows loss of the acidic cerumen film and epithelial disruption. Prolonged antibacterial ear drops are the single most important iatrogenic cause, eliminating competing flora and providing a moist vehicle. Corticosteroid containing drops compound this by local immunosuppression.

Predisposing factors

  • Antibacterial or steroid ear drops used beyond 10 to 14 days.
  • Humid climate, swimming, occlusive hearing aids and earphones.
  • Self instrumentation with cotton buds.
  • Open mastoid cavity, which retains keratin and cannot self clean.
  • Diabetes mellitus, HIV, chemotherapy, long term corticosteroids.
  • Tympanic membrane perforation, which allows fungal colonisation of the middle ear mucosa.

Invasive disease is rare and confined to the immunocompromised, where Aspergillus penetrates the canal floor and produces fungal skull base osteomyelitis with a mortality far exceeding that of pseudomonal disease.

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Continue reading · Surgery

Recurrent Tonsillitis

Repeated discrete episodes of acute tonsillitis with complete resolution between episodes. It is defined by frequency and severity thresholds because these determine whether tonsillectomy delivers benefit that exceeds its risk.

Why recurrence happens

  • Bacterial biofilms within the tonsillar crypts, which resist antibiotic penetration and host clearance and reactivate with each viral trigger.
  • Beta lactamase producing organisms in the crypts, principally Haemophilus influenzae, Staphylococcus aureus, Moraxella catarrhalis and anaerobes, which inactivate penicillin locally even when the pathogen is a susceptible Streptococcus pyogenes. This is the mechanism of apparent penicillin failure in a patient with a penicillin sensitive organism.
  • Streptococcal carriage, in which the organism colonises without invading, with viral illnesses producing symptoms that are then attributed to the streptococcus.
  • Impaired local immunity and, occasionally, systemic immunodeficiency.
  • High exposure settings: young children, day care, teachers, healthcare workers, large households.

Threshold criteria, commonly known as the Paradise criteria, which define the group in whom tonsillectomy has demonstrated benefit:

  • Seven or more adequately documented episodes in the preceding year, or
  • Five or more episodes per year in each of the preceding 2 years, or
  • Three or more episodes per year in each of the preceding 3 years.

Each episode must have been clinically significant, with sore throat plus at least one of temperature above 38.3 degrees Celsius, cervical lymphadenopathy, tonsillar exudate, or a positive test for group A streptococcus, and each must have been treated appropriately and documented at the time.

The evidence position, stated honestly

Tonsillectomy in children meeting the strict criteria reduces episodes by around three per year in the first year, with the difference narrowing thereafter. In adults, the reduction in days with sore throat is smaller but still meaningful. Many children improve spontaneously with time regardless of surgery. The decision is therefore a genuine balance of a modest, temporary benefit against a real risk of haemorrhage and a painful recovery, and it belongs to the informed patient or family.