What antibiotics (Abx) are used to treat salmonella infections?

Antibiotic Treatment for Salmonella Infections

Antibiotics are NOT routinely recommended for uncomplicated Salmonella gastroenteritis in immunocompetent patients, as they do not shorten illness duration and may prolong bacterial shedding and increase adverse effects. 1, 2

When Antibiotics ARE Indicated

Antibiotic therapy should be reserved for specific high-risk populations where systemic spread is a concern:

High-Risk Populations Requiring Treatment 1, 3

• Infants < 6 months of age 1
• Adults > 50 years of age 1
• HIV-infected or immunocompromised patients (including those on anti-TNF therapy, corticosteroids, or other immunosuppressants) 1, 3
• Pregnant women (due to risk of placental/amniotic fluid infection) 1, 3
• Patients with prosthetic devices, valvular heart disease, severe atherosclerosis, malignancy, or uremia 1
• Patients with severe or invasive disease (bacteremia, septicemia, or extraintestinal manifestations) 1, 3

First-Line Antibiotic Choices

For Adults (Immunocompetent with Indications) 1, 3, 4

Fluoroquinolones are the drugs of choice:

• Ciprofloxacin 500 mg PO twice daily for 5-7 days 1, 4
• Alternative fluoroquinolones: Ofloxacin 300 mg or norfloxacin 400 mg twice daily 1

Alternative agents (if fluoroquinolone-resistant or contraindicated): 1, 3, 5

• TMP-SMZ (if susceptible) 1
• Ceftriaxone (third-generation cephalosporin) 1, 5
• Azithromycin (increasingly preferred due to less resistance development and better safety profile) 1, 5

For Children 1, 3, 6

Fluoroquinolones should be avoided in children < 18 years due to arthropathy risk. 1, 4

Preferred pediatric options:

• TMP-SMZ (5 mg/kg trimethoprim component twice daily) 1
• Ceftriaxone 100 mg/kg/day (in 1-2 divided doses) 1, 6, 5
• Cefotaxime 1
• Ampicillin (if susceptible) 1
• Azithromycin (emerging as preferred option) 1, 5
• Chloramphenicol (if other options unavailable) 1

For Pregnant Women 1, 3

Fluoroquinolones are contraindicated in pregnancy. 1

Safe options include:

• Ampicillin 1, 3
• Ceftriaxone or cefotaxime 1, 3
• TMP-SMZ (avoid in first trimester and near term) 1, 3

Treatment Duration by Clinical Scenario

Immunocompetent Patients (when treatment indicated) 1

• 5-7 days of therapy 1

HIV-Infected/Immunocompromised Patients 1, 3

• CD4 > 200 cells/μL: 7-14 days 3
• CD4 < 200 cells/μL: 2-6 weeks 3
• Severe immunosuppression or gastroenteritis: 14 days (ciprofloxacin 750 mg twice daily) 1
• Salmonella septicemia: Long-term suppressive therapy required to prevent recurrence 1, 3

Invasive/Severe Disease 1

• 14 days or longer if relapsing 1

Critical Pitfalls to Avoid

Do NOT use antimotility agents (loperamide, diphenoxylate): 1

• Contraindicated in children < 18 years 1
• Contraindicated if high fever or bloody stools present 1
• Discontinue if symptoms persist > 48 hours 1

Antibiotic resistance concerns: 6, 5, 7

• Increasing fluoroquinolone resistance is a major problem 6, 5
• Extended-spectrum beta-lactamase (ESBL) production emerging 6
• Multidrug-resistant strains increasingly common 6, 5
• Always obtain cultures and susceptibility testing before initiating therapy when possible 1, 4

Paradoxical effects of antibiotics in uncomplicated cases: 2

• Antibiotics prolong fecal shedding of Salmonella beyond 3 weeks 2
• Increase relapse rates 2
• Increase adverse drug reactions (OR 1.67) 2
• Provide no clinical benefit in otherwise healthy patients 2

Supportive Care (All Patients) 3

• Fluid and electrolyte replacement is the cornerstone of therapy 3
• Oral rehydration preferred for mild-moderate dehydration 3
• IV fluids for severe dehydration 3
• Ondansetron may facilitate oral rehydration in children > 4 years with vomiting 3

Secondary Prophylaxis

HIV-infected patients with Salmonella septicemia require chronic suppressive therapy with fluoroquinolones (typically ciprofloxacin) to prevent recurrence. 1, 3

Household contacts of HIV-infected patients should be screened for asymptomatic carriage to prevent reinfection. 1, 3