GI

Common Culprits: Salmonella spp, Campylobacter spp, E. coli spp, Shigella spp, C. difficile, Campylobacter jejuni, Yersinia enterocolitica. Diagnosis is made by stool culture. 

Treatment: 

• E. coli: avoid antibiotics

• Salmonella: antibiotics not indicated for immunocompetent individuals between 12 months and 50 years of age with Salmonella gastroenteritis and mild to moderate symptoms

  1. Children

     • Azithromycin 10 mg/kg on day 1 (maximum 500 mg), followed by 5 mg/kg (maximum 250 mg) daily for four additional days

  2. Adolescents and Adults: Therapy duration 3-7 days

     • Ciprofloxacin 500 mg orally twice daily 

     • Levofloxacin 500 mg orally once daily

     • Trimethoprim-sulfamethoxazole (160 mg/800 mg orally twice daily)

     • Cefixime (400 mg orally once or twice daily)

     • Azithromycin (1 gram, followed by 500 mg daily for five to seven days). It should be noted that antimicrobial resistance testing of Salmonellae for azithromycin susceptibility is not standardized and may not be performed by many laboratories.

     • Amoxicillin (high dose: 1 gram orally three times daily)

• Shigella 

  1. Azithromycin 12 mg/kg orally once daily on day 1 (max dose 500mg/day on day 1); 6 mg/kg orally once daily for 2 to 4 days (max dose 250mg/day for subsequent days) 

     • Preferred

  2. Cefixime 8 mg/kg per day orally in 1 or 2 divided doses for 3 to 5 days (max dose 400mg/day)

     • Preferred for Shigella acquired in South Asia

  3. Ceftibuten 9 mg/kg orally once daily for 3 to 5 days (max dose400 mg/day)

     • Preferred for Shigella acquired in South Asia

  4. Ciprofloxacin 20 mg/kg per day orally in 2 divided doses for 3 to 5 days (max dose 1.5 g/day) 

     • For children <18 years: Use only if no other safe and effective alternative available

     • Dose needs to be adjusted in setting of decreased/decreasing GFR

• C. difficile 

  1. Vancomycin 40 mg/kg per day orally in four divided doses (maximum 125 mg/dose) for 10 days

     • Preferred for severe disease

  2. Metronidazole 30 mg/kg per day orally in four divided doses (maximum 500 mg/dose) for 10 days

  3. Fidaxomicin 4 to <7 kg: 80 mg orally twice daily for 10 days, 7 to <9 kg: 20 mg orally twice daily for 10 days, 9 to <12.5 kg: 60 mg orally twice daily for 10 days, ≥12.5 kg: 200 mg orally twice daily for 10 days

• Campylobacter

  1. Azithromycin 10 mg/kg/dose once daily for 3 days (max dose 500mg/dose)

     • Preferred

  2. Ciprofloxacin 10 to 15 mg/kg/dose every 12 hours (max 750 mg/dose) for 3 to 5 days

• Y. enterocolitica: treatment not generally indicated for mild infections

Special Considerations: These recommendations are for immunocompetent patients

Common Culprit: Enterobius vermicularis

Treatment:

1. Albendazole (adults and children: 400 mg orally once on empty stomach, repeat in two weeks)

2. Mebendazole (adults and children: 100 mg orally once, repeat in two weeks)

3. Pyrantel pamoate (adults and children: 11 mg/kg, maximum 1 g; repeat in two weeks; available over the counter in the United States)

Special considerations: Diagnosis should not be made off of stool samples, eggs and worms are rarely present in stool

Common Culprit: Giardia lamblia 

Treatment:

1. Tinidazole

   • Age ≥3 years: 50 mg/kg orally, single dose (maximum dose 2 g)

2. Nitazoxanide

   • Age 1 to 3 years: 100 mg orally 2 times per day for 3 days

   • Age 4 to 11 years: 200 mg orally 2 times per day for 3 days

   • Age ≥12 years: 500 mg orally 2 times per day for 3 days

3. Metronidazole

   • 15 mg/kg orally divided 3 times per day for 5 to 7 days (maximum 250 mg per dose)

     • Use in patients <12 months

Special Considerations: Many infections are self-limited, and may be able to forego treatment with antibiotics in cases with mild symptoms

Common Culprit: H. pylori 

Treatment (unknown antimicrobial susceptibility) 14-day regimen:

1. Bismuth (<10 years: 262 mg 4 times daily, ≥10 years: 524 mg 4 times daily)+ omeprazole or esomeprazole (15 to <25 kg: 20 mg twice daily, 25 to 34 kg: 30 mg twice daily, ≥35 kg: 40 mg twice daily)+Metronidazole (15 to <25 kg: 250 mg twice daily, 25 to 34 kg: 500 mg AM, 250 mg PM, ≥35 kg: 500 mg twice daily) +Tetracycline (500 mg 4 times daily)

   • ≥8 years

   • PCN allergy

2. Bismuth-PPI-AMO-MET Bismuth (<10 years: 262 mg 4 times daily, ≥10 years: 524 mg 4 times daily)+ omeprazole or esomeprazole (15 to <25 kg: 20 mg twice daily, 25 to 34 kg: 30 mg twice daily, ≥35 kg: 40 mg twice daily)+Metronidazole (15 to <25 kg: 250 mg twice daily, 25 to 34 kg: 500 mg AM, 250 mg PM, ≥35 kg: 500 mg twice daily) + Amoxicillin (15 to <25 kg: 500 mg twice daily, 25 to 34 kg: 750 mg twice daily, ≥35 kg: 1000 mg twice daily)

   • <8 years

3. Omeprazole or esomeprazole (15 to <25 kg: 20 mg twice daily, 25 to 34 kg: 30 mg twice daily, ≥35 kg: 40 mg twice daily) + Amoxicillin (high dose): (15 to <25 kg: 750 mg twice daily, 25 to 34 kg: 1000 mg twice daily, ≥35 kg: 1500 mg twice daily) + Metronidazole (15 to <25 kg: 250 mg twice daily, 25 to 34 kg: 500 mg AM, 250 mg PM, ≥35 kg: 500 mg twice daily) 

Special Considerations: treatment fails to eradicate H. pylori in at least 20 percent of patients in the real-world setting. Antibiotic susceptibility testing should be performed on cultures.

Common Culprit: Trichuris trichiura

Treatment:

1.  Albendazole 400 mg orally once daily for three days 

2. Mebendazole 100 mg orally twice daily for three days

3. Albendazole 400 mg orally once daily for three days plus ivermectin 600 mcg/kg once daily for three days