What is the recommended treatment for Listeria meningitis?

Treatment of Listeria Meningitis

Ampicillin or amoxicillin plus gentamicin is the recommended first-line treatment for Listeria meningitis, with co-trimoxazole being an excellent alternative in cases of penicillin allergy or treatment failure. 1

First-line Treatment Regimen

For Adults (>18 years)

• Ampicillin: 2g IV every 4 hours 1 OR
• Amoxicillin: 2g IV every 4 hours 1

PLUS

• Gentamicin: Initially 5-7 mg/kg/day in divided doses, adjusted based on renal function and drug levels 2, 3

Duration of Treatment

• Minimum 21 days for Listeria meningitis 1
• Treatment should continue until clinical recovery is complete

Alternative Treatment Options

For Penicillin-Allergic Patients

• Co-trimoxazole: 10-20 mg/kg/day (of the trimethoprim component) in 4 divided doses 1, 4
  • Co-trimoxazole has excellent CSF penetration and may be superior to aminoglycoside combinations in some cases 4

Special Considerations

Treatment Failures

• If no clinical improvement after 48-72 hours on ampicillin/gentamicin:
  • Consider adding or switching to co-trimoxazole 5, 4
  • A study showed significantly lower failure rates with ampicillin/co-trimoxazole (6.7%) compared to ampicillin/aminoglycoside (57%) 4

Corticosteroids

• Dexamethasone is NOT recommended in Listeria meningitis
• If dexamethasone was started empirically, discontinue it once Listeria is identified 1
• Observational data shows increased mortality when dexamethasone is used in neurolisteriosis 1

Treatment Algorithm

1. Confirm diagnosis: CSF analysis, blood cultures (sensitivity of CSF culture for Listeria is only 25-35%) 1

2. Initiate treatment immediately:

   • Start ampicillin/amoxicillin plus gentamicin without delay
   • Do not wait for culture results if Listeria is suspected

3. Monitor response:

   • Clinical improvement should be evident within 48-72 hours
   • Consider repeat lumbar puncture if no improvement

4. Adjust treatment based on response:

   • If improving: continue for full 21-day course
   • If not improving: consider adding/switching to co-trimoxazole

Risk Factors for Listeria Meningitis

Empiric coverage for Listeria should be included for patients with:

• Age >50 years
• Age >18 and <50 years with:
  • Diabetes mellitus
  • Immunosuppressive drug use
  • Cancer
  • Other immunocompromising conditions 1

Common Pitfalls to Avoid

1. Inadequate dosing: Ensure high-dose ampicillin/amoxicillin (>6g/day) to achieve adequate CSF concentrations 3

2. Insufficient duration: Treat for at least 21 days; shorter courses risk relapse 1

3. Relying on cephalosporins alone: Cephalosporins have NO activity against Listeria and should not be used as monotherapy 1

4. Continuing dexamethasone: Unlike in pneumococcal meningitis, dexamethasone may worsen outcomes in Listeria meningitis 1

5. Delayed treatment: Start appropriate antibiotics immediately when Listeria is suspected, as mortality remains high (approximately 30%) despite appropriate therapy 2, 3