What is the recommended treatment for Listeriosis?

Treatment of Listeriosis

The recommended treatment for listeriosis is ampicillin or amoxicillin, preferably in combination with gentamicin, for a duration of 2-3 weeks. 1, 2, 3

First-Line Treatment Options

• Ampicillin (2g IV every 4 hours) plus gentamicin is the treatment of choice for listeriosis, as this combination provides synergistic bactericidal activity against Listeria monocytogenes 1, 2, 4
• For patients with CNS involvement (meningitis/encephalitis), high-dose therapy is required due to poor penetration of these antibiotics into the cerebrospinal fluid 3
• Treatment duration should typically be 2-3 weeks to ensure complete eradication of the infection 3

Alternative Treatment Options

• Trimethoprim-sulfamethoxazole (TMP-SMX) is the preferred alternative for penicillin-allergic patients 1, 2
• Other second-line agents include:
  • Erythromycin 2, 5
  • Vancomycin 2, 5
• Fluoroquinolones have shown some activity but clinical data are limited 3

Important Considerations

• Cephalosporins should NOT be used for treating listeriosis as they lack activity against L. monocytogenes 1, 2, 4
• Dexamethasone, which is sometimes used as adjunctive therapy in bacterial meningitis, should be discontinued if Listeria is identified as the causative pathogen 1
• A French cohort study showed that dexamethasone use within the first 24 hours of neurolisteriosis treatment was associated with increased mortality 1

Special Populations

Pregnant Women

• Pregnant women are approximately 18 times more likely to develop listeriosis than the general population due to pregnancy-related immune suppression 6
• Prompt treatment with ampicillin or amoxicillin is crucial to prevent fetal infection 6
• Maternal listeriosis typically presents as a mild febrile illness but can lead to severe fetal and neonatal complications 6
• Fetal listeriosis has a high mortality rate of 25-35%, while neonatal listeriosis has a case fatality rate of approximately 20% 6

Immunocompromised Patients

• HIV-infected individuals and other immunocompromised patients are at higher risk for listeriosis 1
• For patients over 50 years or those with risk factors for listeriosis (diabetes mellitus, immunosuppressive drugs, cancer), empiric treatment for suspected bacterial meningitis should include coverage for Listeria with ampicillin/amoxicillin in addition to standard therapy 1

Prevention

• Immunocompromised individuals, especially those with HIV infection, should avoid:

  • Soft cheeses (feta, Brie, Camembert, blue-veined, and Mexican-style cheese such as queso fresco)
  • Ready-to-eat foods unless reheated until steaming hot
  • Delicatessen counter foods unless heated/reheated until steaming
  • Refrigerated pâtés and meat spreads
  • Raw or unpasteurized milk or milk products 1

• Pregnant women should follow the same preventive measures due to their increased risk of listeriosis 1, 6

Treatment Challenges

• Despite appropriate antibiotic therapy, the cure rate for listeriosis is only approximately 70% 3
• The intracellular habitat of L. monocytogenes limits the efficacy of many antibiotics 4, 3
• The need for prolonged high-dose therapy and the poor penetration of antibiotics into the CNS contribute to treatment challenges 3