Mastoiditis occurs when suppurative infection extends from a middle ear affected by otitis media to the mastoid air cells. The infective process causes inflammation of the mastoid and surrounding tissues and may lead to bony destruction.

Epidemiology

• Mastoiditis in acute or chronic form is now quite rare.
• The incidence in developed countries is 1.2-6.1 per 100,000.
• There is a rising incidence, however, which is connected to restrained antibiotic therapy of AOM, inadequate dosing, choice of antibiotics and increasing resistance of bacteria.
• As serious complications are rare, guidance is that the routine use of antibiotics in AOM is not thought to be justified by the potential reduction in risk of these complications.

Risk factors

• More common in young children, peak incidence of 6-13 months
• Immunocomprimised
• Intellectual impairments or communication difficulties - As can’t communicate Sx
• Pre-existence of cholasteatoma

Infecting organisms

• Streptococcus pneumoniae (most frequently isolated).
• Streptococcus pyogenes.
• Staphylococcus spp.
• Haemophilus influenzae (this is quite rare).
• Pseudomonas aeruginosa (becoming increasingly common).