Drug of Choice for Bacterial Enteritis
For most cases of bacterial enteritis, supportive care without antibiotics is the preferred approach, but when antimicrobial therapy is indicated—particularly in severe illness, immunocompromised patients, or specific pathogens—azithromycin is the drug of choice for Campylobacter, ciprofloxacin (or fluoroquinolones) for Shigella and traveler's diarrhea, and ciprofloxacin for Salmonella in immunocompromised patients. 1
When to Treat Bacterial Enteritis
The decision to use antibiotics should be made clinically before culture results are available, based on severity of presentation 2:
- Severe illness indicators requiring treatment: High fever with shaking chills, bloody stools, signs of dehydration, or immunocompromised status 1
- Mild diarrhea: Antiperistaltic agents (e.g., loperamide) can be used, but must be discontinued if symptoms worsen 1
- Contraindications to antiperistaltics: High fever or blood in stool 1
Pathogen-Specific Treatment Recommendations
Campylobacter Species
Azithromycin has become the drug of choice due to increasing fluoroquinolone resistance (19%). 1 This represents a shift from older recommendations, as fluoroquinolone resistance in Campylobacter develops rapidly during treatment 3.
Shigella Species
Ciprofloxacin or another fluoroquinolone is the treatment of choice, with azithromycin as an effective alternative. 1 Two randomized controlled trials established this as the standard approach 1.
Salmonella Species
Treatment approach depends on immune status:
Immunocompromised patients (including HIV-infected): Should receive antimicrobial therapy to prevent extraintestinal spread 1
Salmonella bacteremia: Combination therapy with ceftriaxone plus ciprofloxacin is recommended to avoid initial treatment failure before resistance results are available, allowing subsequent de-escalation to monotherapy 1
Immunocompetent patients: Antibiotic treatment is controversial, as certain studies indicate antimicrobial therapy can lengthen the shedding period 1. Treatment should be reserved for severe cases 3.
Yersinia Species
Fluoroquinolone or TMP-SMZ or doxycycline is suggested for treatment. 1 For severe disease, a third-generation cephalosporin combined with gentamicin is preferred 1.
Traveler's Diarrhea
Fluoroquinolones (ciprofloxacin, norfloxacin, ofloxacin, or fleroxacin) are drugs of choice, with regimens ranging from single-dose to 5-day treatment courses. 3, 4 These significantly reduce intensity and severity of symptoms 3.
Special Populations
HIV-Infected Patients
- Salmonella septicemia: Requires long-term secondary prophylaxis with fluoroquinolones (primarily ciprofloxacin) to prevent recurrence 1
- Household contacts should be evaluated for asymptomatic carriage to prevent recurrent transmission 1
Children
- HIV-infected children with severe immunosuppression: Should receive treatment for Salmonella gastroenteritis to prevent extraintestinal spread 1
- Antibiotic choices: TMP-SMZ, ampicillin, cefotaxime, ceftriaxone, or chloramphenicol 1
- Fluoroquinolones: Should be used with caution and only if no alternatives exist 1
- Antiperistaltic drugs: Not recommended in children 1
Pregnant Women
- Salmonella gastroenteritis: Should receive treatment due to risk of placental and amniotic fluid infection leading to pregnancy loss 1
- Treatment options: Ampicillin, cefotaxime, ceftriaxone, or TMP-SMZ 1
- Avoid: Fluoroquinolones should not be used during pregnancy 1
Critical Limitations and Pitfalls
Fluoroquinolone Resistance
A major caveat is that quinolone-resistant E. coli have become common in some communities, and quinolones should not be used unless hospital surveys indicate ≥90% susceptibility of E. coli to quinolones. 1 This is particularly important given that resistance develops rapidly in Campylobacter species during treatment 3.
Treatment Timing
Early initiation of treatment (within 48 hours of symptom onset) is of major importance for therapeutic efficacy, particularly in severely ill patients. 3 The benefit of quinolone treatment resembles that observed in early treatment of traveler's diarrhea when started promptly 3.
Failure to Eradicate Salmonella
Quinolones fail to eradicate Salmonella species in many cases, limiting their usefulness for routine empirical treatment of Salmonella enteritis. 3 Treatment should be restricted to early empirical treatment of severely ill and vulnerable patients with underlying health problems 3.
When NOT to Treat
Uncomplicated Salmonella and Campylobacter enteritis: Results from trials evaluating quinolone treatment have generally been disappointing, with differences of doubtful clinical importance 3. Reserve treatment for severe cases or immunocompromised patients.