Acute Mastoiditis

Case Definition:

An infection of the mastoid air cell system and may arise as a complication of acute otitis media. Common causative organisms are Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis. Less common causes are Group A Streptococci, and Staphylococcus aureus. Chronic mastoditis may follow. Chronic suppurative otitis media (cholesteatoma); surgical intervention is usually the treatment of choice.


Diagnostic criteria:

Otalgia that is not settling with tenderness over the mastoid antrum. The external ear canal may be narrowed by oedema of the posterior-superior wall. A subperiosteal abscess can develop posteriorly behind the ear pushing the ear downwards and forwards. Often these classic signs may not be present leading to the term ‘masked mastoiditis’. Clinical suspicion of the presence of mastoiditis is required and a CT or MRI scan is usually required to confirm the diagnosis.


Specimens to be collected:

  • Ideally from the post-auricular abscess or mastoid cavity following surgical drainage

1st line oral/iv antibiotics

Penicillin allergy
(see explanatory notes)

Minor to severe life threatening infection 

Review doses in renal impairment



CO-AMOXICLAV 625mg po tds or 1.2g iv tds




Typical total duration: 2-4 weeks

LEVOFLOXACIN 500mg po/iv bd

(Oral route preferred. Consider reducing to 500mg od if patient clearly improving)


METRONIDAZOLE 400mg po tds

(500mg iv tds treatment only if critically ill, nil by mouth, or concern re. patient's ability to absorb drugs following oral administration)

Typical total duration: 2-4 weeks

IV to Oral Switch (explanatory notes

CO-AMOXICLAV 625mg po tds


Typical total duration: 2-4 weeks

LEVOFLOXACIN 500mg po od
METRONIDAZOLE 400mg po tds

Typical total duration: 2-4 weeks

Last reviewed 23/04/14

For guidance on the administration of intravenous antibiotics
click here (GHNHSFT intranet only)