What is the recommended treatment for a patient with a mastoid bone infection, possibly with a history of ear infections or other underlying conditions?

Treatment of Mastoid Bone Infection (Mastoiditis)

Immediate Initial Management

Start intravenous cloxacillin/flucloxacillin at 50 mg/kg every 6 hours (2g every 6 hours in adults) immediately upon diagnosis, and reassess after 48 hours to determine if surgical intervention is needed. 1

• Ceftriaxone IV at 50-80 mg/kg daily serves as the second-line antibiotic option if cloxacillin/flucloxacillin is contraindicated or unavailable 1
• Pain management is paramount and should be initiated immediately alongside antibiotics 1, 2
• Consider myringotomy with or without tympanostomy tube insertion at the time of diagnosis to facilitate drainage 1, 2

Clinical Features Requiring Recognition

• Key distinguishing features from uncomplicated acute otitis media include mastoid tenderness, retroauricular swelling, and protrusion of the auricle 1
• Fever (83%), abnormal tympanic membrane (88%), narrowed external auditory canal (80%), and postauricular edema (76%) are the most common physical findings 3
• Important caveat: 45% of patients have no history of antecedent acute otitis media, and 33-81% of patients will have already received antibiotics before diagnosis 1, 3, 4

48-Hour Reassessment Algorithm

After initiating IV antibiotics, perform clinical reassessment at 48 hours 1, 2:

• If improving clinically: Continue IV antibiotics for 7-10 days total, then transition to oral antibiotics based on culture results 5
• If no improvement or clinical deterioration: Obtain CT temporal bone with IV contrast and proceed to surgical intervention 1, 2
• If subperiosteal abscess present: Mastoidectomy is required (needle aspiration may be attempted first for simple abscesses without cholesteatoma) 1, 5

Surgical Indications

Proceed to mastoidectomy if any of the following are present 1, 2:

• No clinical improvement after 48 hours of IV antibiotics
• Development of complications (intracranial extension, facial nerve palsy, labyrinthitis)
• Presence of subperiosteal abscess
• Evidence of cholesteatoma
• Bony erosion or coalescence on imaging 6

Treatment success rates vary significantly: antibiotics alone achieve only 10% success, antibiotics plus myringotomy achieve 68% success, and antibiotics plus mastoidectomy achieve 97% success 1, 7, 6

Imaging Strategy

• Obtain CT temporal bone with IV contrast if the patient fails to improve after 48 hours or deteriorates at any point 2, 5
• CT provides high spatial resolution for assessing bony erosion and intratemporal complications 2
• Consider MRI without and with IV contrast if intracranial complications are suspected (brain abscess, subdural empyema, meningitis, or dural venous sinus thrombosis), as MRI has higher sensitivity than CT for these complications 2

Bacteriology and Culture-Guided Therapy

• Streptococcus pneumoniae remains the most common pathogen despite PCV-13 vaccination, followed by Streptococcus pyogenes, Staphylococcus aureus, Haemophilus influenzae, and Pseudomonas aeruginosa 1, 8, 3
• Cultures from mastoid infections may be negative in 33-53% of cases, emphasizing the importance of clinical diagnosis and empiric therapy 1
• For patients failing initial therapy, adjust antibiotics based on culture results when available; consider clindamycin with or without coverage for H. influenzae and Moraxella catarrhalis 2

Complicated Mastoiditis Requiring Broader Coverage

For complicated cases with intracranial extension or severe disease, use broader antibiotic coverage 2:

• Vancomycin PLUS one of the following: piperacillin-tazobactam, a carbapenem, ceftriaxone plus metronidazole, or a fluoroquinolone plus metronidazole
• For confirmed Streptococcus pyogenes, consider adding clindamycin to penicillin therapy 2
• Vancomycin should be administered over at least 60 minutes to avoid infusion-related reactions 9

Complications Requiring Vigilant Monitoring

Monitor for the following serious complications 1, 2, 8:

• Intracranial: Brain abscess (most common intracranial complication), subdural empyema, meningitis, sigmoid sinus thrombosis
• Intratemporal: Facial nerve palsy, labyrinthitis
• Extracranial: Subperiosteal abscess, Bezold's abscess
• No reliable clinical signs distinguish patients with coexistent intracranial complications, making imaging crucial in non-resolving cases 2

Postoperative and Follow-Up Care

• Continue IV antibiotics for 7-10 days postoperatively, then transition to oral antibiotics based on culture results 5
• Persistent middle ear effusion is common after resolution of acute symptoms and should be monitored 2
• Perform hearing assessment if effusion persists for ≥3 months 2
• Regular follow-up is essential to ensure complete resolution and monitor for recurrence 2

Critical Pitfalls to Avoid

• Do not assume prior antibiotic treatment prevents mastoiditis development - this occurs in 33-81% of cases 1, 4
• Do not delay imaging in non-resolving cases - intracranial complications can develop rapidly 2
• Do not rely solely on antibiotics for complicated cases - success rate is only 10% without surgical intervention 1, 7
• Do not overlook the possibility of cholesteatoma - its presence mandates mastoidectomy rather than conservative management 5
• Amoxicillin-clavulanate should be taken with meals to reduce gastrointestinal upset 10
• Monitor for Clostridium difficile associated diarrhea, which can occur up to 2 months after antibiotic administration 9