Should I take antibiotics for food poisoning?

Antibiotics for Food Poisoning

Most cases of food poisoning do not require antibiotics and should be managed with rehydration alone. 1, 2 Empiric antibiotics are only indicated in specific high-risk situations, and indiscriminate use can worsen outcomes—particularly in Shiga toxin-producing E. coli (STEC) infections where antibiotics increase the risk of hemolytic uremic syndrome. 1

When Antibiotics Are NOT Indicated

• Uncomplicated watery diarrhea without fever or blood in otherwise healthy adults and children should never receive antibiotics. 1, 2
• Confirmed or suspected STEC O157:H7 or other Shiga toxin 2-producing E. coli infections are an absolute contraindication to antibiotics, as they significantly increase the risk of hemolytic uremic syndrome. 1
• Asymptomatic household contacts of patients with diarrhea should not receive antibiotics. 1
• Non-typhoidal Salmonella gastroenteritis in healthy adults generally should not be treated with antibiotics, as they may prolong bacterial shedding without clinical benefit. 3, 1
• Staphylococcal food poisoning (toxin-mediated) does not respond to antibiotics and requires only supportive care. 4

When Antibiotics ARE Indicated

Empiric antibiotics should be started immediately in the following situations:

• Infants less than 3 months of age with suspected bacterial etiology. 1
• Fever, abdominal pain, and bloody diarrhea suggesting bacillary dysentery (presumptively Shigella). 1
• Recent international travelers with temperature ≥38.5°C and/or signs of sepsis. 1
• Immunocompromised patients with severe illness and bloody diarrhea. 1, 5
• Clinical features of sepsis with suspected enteric fever. 1
• High-risk patients with non-typhoidal Salmonella: those <6 months or >50 years old, or with prosthetic devices, valvular heart disease, severe atherosclerosis, malignancy, or uremia. 1

First-Line Antibiotic Choice

Azithromycin is the preferred first-line empiric antibiotic for food poisoning requiring treatment. 1

• Adult dosing: Single 1-gram dose OR 500 mg daily for 3 days. 1
• Rationale: Fluoroquinolone-resistant Campylobacter now exceeds 90% in many regions (Thailand, India, Southeast Asia), making azithromycin superior. 1
• Coverage: Effective against Campylobacter, Shigella, Salmonella, and most common bacterial pathogens. 1

Second-Line Options (When Azithromycin Is Unavailable)

• Ciprofloxacin: 500 mg twice daily for 3-5 days OR single 750 mg dose for moderate-to-severe cases. 1 Use only in regions with documented low fluoroquinolone resistance. 1
• Ceftriaxone: 2g IV daily for severe infections, bacteremia, or infants <3 months. 6

Pediatric Considerations

• Infants <3 months: Use third-generation cephalosporin (ceftriaxone 50 mg/kg/day IM/IV), NOT azithromycin or fluoroquinolones. 1, 6
• Children >3 months: Azithromycin is preferred based on local susceptibility patterns. 1
• Fluoroquinolones should be avoided in children <18 years except when no alternatives exist. 3, 1

Critical Pitfall to Avoid

Never start antibiotics for bloody diarrhea without first ruling out STEC. 1 Obtain stool culture and Shiga toxin testing before initiating therapy. 1 If STEC is confirmed, antibiotics are contraindicated and may precipitate life-threatening hemolytic uremic syndrome. 1

Management Algorithm

1. Assess for danger signs: bloody diarrhea, high fever (≥38.5°C), signs of sepsis, severe dehydration, immunocompromised status, age <3 months or >50 years. 1, 5

2. If bloody diarrhea is present: Obtain stool culture and Shiga toxin testing BEFORE starting antibiotics. 1

3. Start rehydration immediately with reduced osmolarity oral rehydration solution (ORS) for mild-to-moderate dehydration, or IV fluids for severe dehydration, shock, or altered mental status. 1 Rehydration is the cornerstone of treatment regardless of antibiotic use. 1, 2

4. If antibiotics are indicated (based on criteria above): Start azithromycin 1 gram single dose or 500 mg daily for 3 days. 1

5. Reassess at 48-72 hours: If no improvement, consider antibiotic resistance, inadequate rehydration, non-infectious causes, or need for hospitalization. 1

6. Modify or discontinue antibiotics once a specific pathogen is identified and susceptibilities are known. 1

Special Populations

• Pregnant women: Avoid fluoroquinolones. 3 Use ampicillin, cefotaxime, ceftriaxone, or TMP-SMZ for Salmonella. 3 Azithromycin is generally safe. 1
• HIV-infected patients: Treat Salmonella gastroenteritis with ciprofloxacin 750 mg twice daily for 14 days to prevent extraintestinal spread, though evidence is limited. 3 Long-term suppressive therapy may be needed for recurrent Salmonella septicemia. 3
• Elderly and diabetic patients: Consider empiric antibiotics due to higher risk of complications. 5

Common Pitfalls

• Overuse of fluoroquinolones: Ciprofloxacin should not be used as first-line due to widespread resistance. 1 The FDA has issued safety warnings about fluoroquinolones and recommends using them only when no more appropriate options are available. 1
• Neglecting rehydration: Focusing solely on antibiotics while ignoring fluid replacement is a critical error. 1, 2
• Treating non-typhoidal Salmonella routinely: Reserve antibiotics only for high-risk patients. 1
• Using antibiotics for viral or toxin-mediated food poisoning: These do not respond to antimicrobial therapy. 4, 7