GASTROINTESTINAL TRACT INFECTIONS

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Peptic Ulcer Disease

Infection/Condition and Likely Organism

Suggested Treatment

Comments

Preferred Treatment

Alternative Treatment

Helicobacter pylori

Triple regimen*

Clarithromycin 500mg PO q12h

PLUS

Amoxicillin 1 gm PO q12h

Metronidazole 400mg PO q12h**

Levofloxacin-based Triple regimen*

Levofloxacin 500mg PO q24h

PLUS

Amoxicillin 1 gm PO q12h

Quadruple therapy* Metronidazole 200mg PO q6h

PLUS

Tetracycline 500mg PO q6h

PLUS

Bismuth subsalicylate 300mg PO q6h

*PLUS

Pantoprazole 40mg PO q12h OR

Omeprazole 20mg PO q12h OR

Esomeprazole 20mg PO 12h OR

Rabeprazole 20mg PO q12h OR

Lansoprazole 30mg PO q12h

Duration of Treatment: 14 days.

**Metronidazole is not preferred as the first line in a triple regimen as its resistance is common in Nepal. The dose can be 400mg q8-12h.

Candidiasis

Infection/Condition and Likely Organism	Suggested Treatment		Comments
Infection/Condition and Likely Organism	Preferred Treatment	Alternative Treatment	Comments
Oropharyngeal Candidiasis	Clotrimazole Mouth Paint 10-20 drops (about 1ml) apply locally q6h OR Nystatin suspension 4-6 lakh Units (4-6ml) locally q6h	Moderate to severe or Unresponsive to topical therapy Fluconazole 200mg orally on Day 1 then 100-200mg orally q24h	Duration – 7-14 days (can be extended to 28 days for refractory disease).
Esophageal Candidiasis	Fluconazole 400mg IV/PO on Day 1 then 200-400mg q24h	Voriconazole 200mg IV/ PO q12h	Duration – 14-21 days (can be extended to 28 days for refractory disease).

Acute Gastroenteritis

Infection/Condition and Likely Organism

Suggested Treatment

Comments

Preferred Treatment

Alternative Treatment

Viral

Entero-toxigenic

Escherichia coli

Entero-pathogenic

Escherichia coli

Food Poisoning

Staphylococcus aureus

Bacillus cereus

Clostridium botulinum

No antibiotics

Rehydration (oral or IV based on hydration status and ability to drink).

Cholera

Infection/Condition and Likely Organism

Suggested Treatment

Comments

Preferred Treatment

Alternative Treatment

Vibrio cholerae

Doxycycline 300mg PO stat

Azithromycin 1 gm PO stat

Ciprofloxacin 500mg PO q12h for 3 days

Dysentery

Infection/Condition and Likely Organism	Suggested Treatment		Comments
Infection/Condition and Likely Organism	Preferred Treatment	Alternative Treatment	Comments
Bacillary dysentery Shigella spp. Campylobacter* Non-typhoidal salmonella	Ceftriaxone 2 gm IV q24h for 5 days OR Cefixime 10-15mg/kg/day PO in divided doses q12h for 5 days	Azithromycin 1 gm PO q24h for 3 days	*For Campylobacter, Azithromycin is the drug of choice, if treatment is indicated.
Bacillary dysentery Shiga toxin-producing Escherichia coli	No antibiotics		Antibiotic use may be associated with hemolytic uremic syndrome.
Amoebic dysentery Entamoeba histolytica	Metronidazole 400mg PO q8h for 7-10 days	Tinidazole 2g PO q24h for 3 days	Add Diloxanide furoate 500mg q8h for 10 days

Giardiasis

Infection/Condition and Likely Organism	Suggested Treatment		Comments
	Preferred Treatment	Alternative Treatment
Giardia lamblia	Tinidazole 2g PO stat	Metronidazole 400mg PO q8h for 7-10 days

Enteric fever

Infection/Condition and Likely Organism

Suggested Treatment

Comments

Preferred Treatment

Alternative Treatment

Enteric fever

Cefixime 20mg/kg/day for 7-14 days

Azithromycin 1g stat on D1 followed by 500mg q24h for total of 5-7 days

Ceftriaxone 2 gm IV q12-24h for 7-14 days

Further treatment modalities in Tropical Infection section

Diarrhea

Infection/Condition and Likely Organism

Suggested Treatment

Comments

Preferred Treatment

Alternative Treatment

Clostridioides difficile Diarrhea

Metronidazole 400mg PO q8h for 10 days

For severe disease

Vancomycin 250mg PO q6h

Peritonitis

Infection/Condition and Likely Organism	Suggested Treatment		Comments
Infection/Condition and Likely Organism	Preferred Treatment	Alternative Treatment	Comments
Spontaneous bacterial peritonitis Enterobacteriaceae Escherichia coli Klebsiella spp.	Cefotaxime 2gm IV q8h	Ceftriaxone 2 gm IV q24h OR Piperacillin-tazobactam 4.5gm IV q6-8h OR Meropenem 1 gm IV q8h	Duration: 5-7 days.
Spontaneous bacterial peritonitis Prophylaxis in cirrhosis	Trimethoprim-sulfamethoxazole 160/800mg PO q24h OR Norfloxacin 400mg PO q24h In GI bleed Ceftriaxone 1 gm IV q24h*		*Switch to oral once bleeding has been controlled and patient is stable and eating.
Secondary peritonitis, Intra-abdominal abscess/ GI perforation Causative Organisms Enterobacteriaceae Escherichia coli Klebsiella spp. Bacteroides (in colonic perforation) Anaerobes	Piperacillin-tazobactam 4.5gm IV q6-8h OR Meropenem 1 gm IV q8h	In very sick patients - PLUS Fluconazole 800mg IV on Day 1 then 400mg q24h PLUS Vancomycin 15-20mg/kg IV (max 2g)	Source control to reduce bacterial load. Duration: 5-7 days if good response and excellent source control. Can be extended to 2-3 weeks depending upon response.

Biliary tract infections

Infection/Condition and Likely Organism

Suggested Treatment

Comments

Preferred Treatment

Alternative Treatment

Cholecystitis, Cholangitis

Amoxicillin-clavulanate 1.2gm IV q8h

Ceftriaxone 2 gm IV q24h

PLUS*

Metronidazole 500mg IV q8h

Piperacillin-tazobactam 4.5gm IV q6-8h

Meropenem 1 gm IV q8h

Duration: 7-10 days Surgical or endoscopic intervention for biliary obstruction.

*If biliary enteric anastomosis is present.

Diverticulitis

Infection/Condition and Likely Organism

Suggested Treatment

Comments

Preferred Treatment

Alternative Treatment

Gram-negative bacteria

Anaerobes

Mild

Amoxicillin-clavulanate 625mg PO q8h for 7 days

Moderate

Ceftriaxone 2 gm IV q24h

PLUS

Metronidazole 500mg IV q8h

Piperacillin-tazobactam 4.5gm IV q6-8h

Severe

Meropenem 1 gm IV q8h

Mild

Ciprofloxacin 500mg PO q12h for 7 days

PLUS

Metronidazole 400mg PO q8h for 7 days

Duration of treatment for moderate and severe diverticulitis: Based on clinical improvement.

Liver abscess

Infection/Condition and Likely Organism	Suggested Treatment		Comments
Infection/Condition and Likely Organism	Preferred Treatment	Alternative Treatment	Comments
Liver abscess (Pyogenic) Klebsiella spp. Escherichia coli Polymicrobial	Ampicillin 2gm IV q4h PLUS Gentamicin 5mg/kg/day IV q24h PLUS* Metronidazole 500mg IV q8h	Ceftriaxone 2 gm IV q24h OR Cefotaxime 2gm IV q8h PLUS* Metronidazole 500mg IV q8h OR Piperacillin-tazobactam 4.5gm IV q6-8h	Duration: 2-4 weeks (if good response to initial drainage) and 4-6 weeks of parenteral therapy for those with incomplete drainage. Consider drainage of abscess if impending rupture or large abscess or no response to medical treatment.
Liver abscess (Amoebic) Entamoeba histolytica	Metronidazole 500-750mg IV q8h OR Tinidazole 2g PO q24h for 5 days PLUS* Diloxanide furoate 500mg PO q8h for 10 days OR Paromomycin 25-30mg/ kg/day PO in three divided doses for 7 days		* Luminal agents Diloxanide furoate or paromomycin are used to eliminate intraluminal cysts even if stool microscopy is negative.

References

Basnyat B, Qamar F N, Rupali P, Ahmed T, Parry C M. Enteric fever BMJ 2021; 372:n437.
Chavez-Tapia NC, Soares-Weiser K, Brezis M, Leibovici L. Antibiotics for spontaneous bacterial peritonitis in cirrhotic patients. Cochrane Database Syst Rev. 2009 Jan 21;2009(1): CD002232.
Drugs for Parasitic Infections, 3rd ed, The Medical Letter, New Rochelle, NY 2013.
Harrison’s Principles of Internal Medicine 20^th
Leibovici-Weissman Y, Neuberger A, Bitterman R, Sinclair D, Salam MA, Paul M. Antimicrobial drugs for treating cholera. Cochrane Database Syst Rev. 2014 Jun 19;2014(6): CD008625. doi: 10.1002/14651858.CD008625.pub2. PMID: 24944120; PMCID: PMC4468928.
National Treatment Guidelines for Antimicrobial Use in Infectious Diseases 2016, National Center for Disease Control, Government of India.
Pappas PG, Kauffman CA, Andes D, et al. Clinical practice guidelines for the management of candidiasis: 2016 update by the Infections Diseases Society of America. Clin Infect Dis 2016; 62:e1.
Miftahussurur M, Shrestha PK, Subsomwong P, Sharma RP, Yamaoka Y. Emerging helicobacter pylori levofloxacin resistance and novel genetic mutation in Nepal. BMC Microbiol. 2016;16(1):256.