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Infectious Disease and Microbiology - Mastoiditis
Mastoiditis is an infection and inflammation of the mastoid air cells of the temporal bone, typically classified as acute or chronic based on duration. Acute mastoiditis usually follows untreated or inadequately treated middle ear infection, whereas chronic mastoiditis is characterized by persistent ear discharge lasting more than three weeks, often associated with a perforated tympanic membrane.
The incidence of mastoiditis has significantly declined in the antibiotic era due to prompt treatment of otitis media. However, a recent shift toward conservative management of ear infections has led to a slight increase in cases in some regions. It remains a relatively rare condition, with incidence rates ranging from approximately 1.2 to 3.8 cases per 100,000 patient-years. Risk factors include inadequate treatment of otitis media, lack of vaccination against Streptococcus pneumoniae and Haemophilus influenzae, and the presence of cochlear implants.
The disease typically develops as an extension of infection from the middle ear into the mastoid air cells. In acute mastoiditis, the most common causative organisms mirror those of acute otitis media, including Streptococcus pneumoniae, Haemophilus influenzae, Streptococcus pyogenes, and Pseudomonas aeruginosa. Chronic mastoiditis is often polymicrobial, involving organisms such as Pseudomonas aeruginosa, Staphylococcus aureus, gram-negative bacilli, anaerobes, and rarely fungi or mycobacteria.
Clinically, patients often present with symptoms of acute otitis media, including fever, ear pain, and hearing impairment. Physical examination reveals erythema of the tympanic membrane, ear discharge (otorrhea), and characteristic postauricular findings such as swelling, tenderness, and redness over the mastoid region. A key sign is displacement of the pinna outward and downward. In chronic cases, symptoms may be more subtle, including persistent ear discharge and hearing loss.
Diagnosis is supported by laboratory findings such as elevated white blood cell count and inflammatory markers (CRP and ESR). Imaging plays a crucial role, with radiographs showing destruction of mastoid air cell septa and fluid accumulation, while CT or MRI provides detailed assessment of disease extent and complications. Microbiological diagnosis is achieved through culture of ear discharge or middle ear fluid obtained via tympanocentesis.
Management requires prompt and aggressive treatment due to the risk of serious complications. Intravenous antibiotics are the mainstay of therapy, typically using broad-spectrum agents such as third- or fourth-generation cephalosporins, piperacillin-tazobactam, or combinations targeting resistant organisms. Treatment duration is usually 3–4 weeks, with transition to oral therapy after clinical improvement. Chronic mastoiditis may also require local antibiotic therapy and meticulous ear care.
Surgical intervention is indicated in cases of treatment failure, complications, or evidence of bone destruction. Procedures such as mastoidectomy are performed to remove infected tissue and prevent further spread. Less invasive approaches, including drainage and ventilation tube placement, may be considered in selected cases without intracranial involvement.
The prognosis is generally very good when mastoiditis is diagnosed early and treated appropriately. However, delayed or inadequate treatment can lead to serious complications, including subperiosteal abscess, facial nerve paralysis, intracranial infections such as meningitis or brain abscess, and permanent hearing loss.
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