Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

gastroenteritis

1st line – supportive care

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ACUTE
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gastroenteritis
|
immunocompetent nonpregnant: <60 years
1st line – 

supportive care

Listeria gastroenteritis is typically self-limited and requires no specific antibiotic treatment.[1][2][6][41]

Maintenance of fluid status and supportive treatment as needed are recommended.

1st line – amoxicillin or trimethoprim/sulfamethoxazole

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ACUTE
|
gastroenteritis
|
immunocompromised or ≥60 years or pregnant
1st line – 

amoxicillin or trimethoprim/sulfamethoxazole

Patients with febrile gastroenteritis who are immunocompromised, of older age (i.e., 60 years or older), or pregnant require treatment with amoxicillin or trimethoprim/sulfamethoxazole.[42]

Penicillins are generally considered to be safe in pregnancy. Trimethoprim/sulfamethoxazole should be avoided during the first trimester of pregnancy due to its effect on folic acid metabolism.[2][20] It could be used in very severe cases, when the benefits outweigh the risks, as an alternative to penicillin therapy; however, there are no adequate studies to support this indication. 

Treatment course: 3-5 days.

Primary options

amoxicillin: children: consult specialist for guidance on dose; adults: 500 mg orally three times daily

OR

sulfamethoxazole/trimethoprim: children: consult specialist for guidance on dose; adults: 160 mg orally twice daily

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systemic infection: not gastroenteritis, not meningitis/meningoencephalitis

1st line – ampicillin

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ACUTE
|
systemic infection: not gastroenteritis, not meningitis/meningoencephalitis
1st line – 

ampicillin

Ampicillin is the drug of choice in patients with systemic infection.[21]​ It is considered safe in pregnancy.[20]

Treatment course: duration of therapy for bacteremia is at least 14 days. Treatment duration for brain abscess is at least 6 weeks.[47][48]​ Recommended duration of therapy for endocarditis is 4-6 weeks. 

Specialist surgical consultation is recommended in the settings of brain abscess and endocarditis.

Repeat blood cultures may be done to help document and confirm clearance of infection in bacteremia and endocarditis. Repeat brain imaging may also help document improvement in CNS abscess treatment.

Primary options

ampicillin: children: consult specialist for guidance on dose; adults: 2 g intravenously every 6 hours

Consider – gentamicin

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ACUTE
|
systemic infection: not gastroenteritis, not meningitis/meningoencephalitis
Consider – 

gentamicin

Treatment recommended for SOME patients in selected patient group

Consideration of combination therapy with gentamicin for 14-21 days is suggested for severe infections, typically bacteremia.[20][21]​​ Gentamicin should be used with caution because of the association with renal failure in two retrospective studies.[43]  

Aminoglycosides should be avoided in pregnancy unless the benefits outweigh the risks, in which case gentamicin may be used due to lesser likelihood of auditory or vestibular nerve damage than with other aminoglycosides. Gentamicin is used only rarely during pregnancy, and only in consultation with an infectious diseases specialist.

Primary options

gentamicin: children: consult specialist for guidance on dose; adults: 5-7 mg/kg intravenously every 24 hours

2nd line – trimethoprim/sulfamethoxazole or meropenem

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ACUTE
|
systemic infection: not gastroenteritis, not meningitis/meningoencephalitis
2nd line – 

trimethoprim/sulfamethoxazole or meropenem

Trimethoprim/sulfamethoxazole is considered an acceptable alternative in penicillin-allergic patients. Meropenem may also be used but it is associated with a higher treatment failure and mortality rate.[45][46]

Trimethoprim/sulfamethoxazole should be avoided during the first trimester of pregnancy.[2] It could be used in very severe cases, when the benefits outweigh the risks, as an alternative to penicillin therapy; however, there are no adequate studies to support this indication. There are no safety and efficacy studies evaluating the implementation of a safe second-line therapy due to penicillin allergy in pregnant women with listeriosis. Alternatives to penicillin may be used but may risk harming the fetus. Consult an infectious disease specialist.

Each case should be individualized.

Treatment course: duration of therapy for bacteremia is typically 14 days. Treatment duration for brain abscess is at least 6 weeks.[47][48]​ Recommended duration of therapy for endocarditis is 4-6 weeks.[49] Duration of treatment in immunocompromised patients is variable and depends upon the individual case.

Specialist surgical consultation is recommended in the settings of brain abscess and endocarditis.

Repeat blood cultures may be done to help document and confirm clearance of infection in bacteremia and endocarditis. Repeat brain imaging may also help document improvement in CNS abscess treatment.

Primary options

sulfamethoxazole/trimethoprim: children ≥2 months of age: consult specialist for guidance on dose; adults: 10-20 mg/kg/day intravenously given in divided doses every 6-12 hours

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OR

meropenem: children ≥3 months of age: consult specialist for guidance on dose; adults: 500 mg intravenously every 8 hours

meningitis/meningoencephalitis

1st line – ampicillin

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ACUTE
|
meningitis/meningoencephalitis
1st line – 

ampicillin

Ampicillin is recommended as first line therapy.[1][42][54]

Penicillins are generally considered to be safe in pregnancy.

The treatment approach should be individualized for each patient, and consultation with infectious disease specialists is recommended.

Expert consultation is strongly recommended for pregnant women with systemic illness.

Treatment course: 21 days.

Primary options

ampicillin: children: consult specialist for guidance on dose; adults: 2 g intravenously every 4 hours

Consider – gentamicin

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ACUTE
|
meningitis/meningoencephalitis
Consider – 

gentamicin

Treatment recommended for SOME patients in selected patient group

Adding gentamicin to ampicillin could be considered to treat L monocytogenes meningitis.[43] It should be used with caution because of the association with renal failure in two retrospective studies.[43]

Aminoglycosides should be avoided in pregnancy unless the benefits outweigh the risks, in which case gentamicin may be used due to lesser likelihood of auditory or vestibular nerve damage than with other aminoglycosides.

The treatment approach should be individualized for each patient, and consultation with infectious disease specialists is recommended.

Expert consultation is strongly recommended for pregnant women with systemic illness.

Treatment course: 21 days.

Primary options

gentamicin: children: consult specialist for guidance on dose; adults: 5-7 mg/kg intravenously every 24 hours

2nd line – trimethoprim/sulfamethoxazole

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ACUTE
|
meningitis/meningoencephalitis
2nd line – 

trimethoprim/sulfamethoxazole

If the patient is penicillin-allergic, trimethoprim/sulfamethoxazole is recommended.[53]

Trimethoprim/sulfamethoxazole is also an alternative treatment for pregnant patients with a penicillin allergy or intolerance, however it should be avoided it is unsafe during the first trimester due to its effect on to the folic acid metabolism.[2][20]

The treatment approach should be individualized for each patient, and consultation with infectious disease specialists is recommended. Expert consultation is strongly recommended for pregnant women with systemic illness.

Treatment course: 21 days.

Primary options

sulfamethoxazole/trimethoprim: children ≥2 months of age: consult specialist for guidance on dose; adults: 10-20 mg/kg/day intravenously given in divided doses every 6-12 hours

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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