What is the recommended treatment for Listeria (Listeria monocytogenes) infection?

Treatment of Listeria Monocytogenes Infection

The first-line treatment for Listeria monocytogenes infection is high-dose intravenous ampicillin or amoxicillin, often in combination with gentamicin for synergistic effect, especially in cases of invasive disease such as meningitis or septicemia. 1, 2

Recommended Treatment Regimens

• For invasive listeriosis (meningitis, endocarditis): 15-20 million units/day of IV penicillin G for 2-4 weeks depending on infection site 3
• For immunocompromised patients: Combination therapy with ampicillin/amoxicillin plus gentamicin is recommended for synergistic effect 2
• For penicillin-allergic patients: Trimethoprim-sulfamethoxazole (TMP-SMX) is the preferred alternative 1, 2
• Fluoroquinolones should be avoided, particularly during pregnancy 4

Treatment Considerations for Special Populations

Pregnant Women

• Prompt treatment is critical as Listeria infection during pregnancy can lead to miscarriage, stillbirth, and neonatal infection 5
• Safe antibiotics for pregnant women with listeriosis include ampicillin, cefotaxime, ceftriaxone, or TMP-SMX 1, 4
• Fluoroquinolones should be strictly avoided during pregnancy 4

Immunocompromised Patients

• Patients on immunosuppressive therapy (especially anti-TNF agents) are at higher risk for severe Listeria infections 1
• Immunosuppressive therapy should be temporarily withheld until resolution of active infection 1
• Higher doses and longer treatment durations may be necessary for immunocompromised patients 3

Clinical Presentation and Diagnosis

• Listeriosis can present as:

  • Mild gastroenteritis with fever, diarrhea, nausea, and vomiting in immunocompetent hosts 2
  • Invasive disease (bacteremia, meningitis) in high-risk populations 6
  • Maternal-fetal infection during pregnancy 5

• Diagnosis is made by:

  • Appropriate microbiological blood and cerebrospinal fluid Gram staining 1
  • Bacterial cultures from blood, CSF, or other sterile sites 1, 2
  • PCR-based detection in patients who have received prior antimicrobial therapy 6

Prevention Strategies

• Prevention of Listeria infection consists of food hygiene and careful food choices 1
• High-risk individuals should avoid:
  • Unpasteurized milk and dairy products 1
  • Soft cheeses made from raw milk 7
  • Raw or undercooked meats 1
  • Ready-to-eat deli meats unless thoroughly heated 2, 5
  • Refrigerated smoked seafood 6

Common Pitfalls and Caveats

• Listeriosis can mimic other infections, leading to delayed diagnosis and treatment 6
• A high index of suspicion is needed for patients on immunosuppressive therapy who present with neurological symptoms 1
• Comprehensive investigation, including lumbar puncture, should be performed promptly when Listeria infection is suspected in high-risk individuals 1
• Between 17% and 33% of all cases of invasive Listeria disease occur among pregnant women, unborn fetuses, or newborn infants, representing a 13-17 fold increase compared with the general population 1
• Mortality remains high (20-30%) in invasive listeriosis despite appropriate antimicrobial therapy 2, 8