What is the best treatment for diarrhea in a patient with a history of Lyme disease who has been on antibiotics that destroyed their microbiome?

Treatment of Antibiotic-Associated Diarrhea in Post-Lyme Disease Patients

Probiotics, specifically Saccharomyces boulardii, should be offered to reduce symptom severity and duration in patients with antibiotic-associated diarrhea following Lyme disease treatment. 1

Initial Assessment

Before initiating treatment, you must rule out Clostridioides difficile infection (CDI), which can occur after any antibiotic use and ranges from mild diarrhea to fatal colitis 2. This is critical because:

• CDI has been reported to occur up to 2 months after antibiotic administration 2
• If CDI is suspected or confirmed, ongoing antibiotics not directed against C. difficile must be discontinued 2
• Patients presenting with worsening diarrhea, fever, or severe abdominal pain require immediate evaluation for CDI 1

First-Line Treatment: Probiotics

Specific Probiotic Recommendations

The most effective probiotic for antibiotic-associated diarrhea is Saccharomyces boulardii I-745, which has demonstrated superior efficacy with minimal adverse effects 3. The evidence supporting this includes:

• Two randomized controlled trials showed S. boulardii combined with standard therapy reduced CDI recurrence rates from 45-50% to 17-26% 1
• The Infectious Diseases Society of America recommends probiotics may be offered to reduce symptom severity and duration in immunocompetent adults with antimicrobial-associated diarrhea 1
• S. boulardii outperforms other probiotic strains including Lactobacillus and Bifidobacterium species 3

Alternative Probiotic Options

If S. boulardii is unavailable, consider a Lactobacilli strain mixture containing L. acidophilus CL1285, L. casei LBC80R, and L. rhamnosus CLR2, which has been tested in multiple hospitals and found effective in reducing CDI rates 1.

Critical Contraindication

Do not prescribe probiotics to immunocompromised patients due to rare but serious risk of bacteremia 1.

Supportive Care

Rehydration Strategy

• Oral rehydration solution (ORS) is the primary treatment for mild to moderate dehydration from any cause of diarrhea 1
• Continue ORS until clinical dehydration is corrected 1
• Replace ongoing stool losses with ORS until diarrhea resolves 1

Dietary Management

• Resume age-appropriate usual diet immediately after rehydration is completed 1
• Consider lactose intolerance as a potential contributor if symptoms persist beyond initial treatment 1

When Antimotility Agents Are Appropriate

Loperamide may be considered once the patient is adequately hydrated, but only if:

• The patient is an immunocompetent adult 1
• There is no fever or bloody diarrhea present 1
• CDI has been ruled out (antimotility drugs should be avoided when toxic megacolon is a risk) 1

Never give antimotility drugs to patients under 18 years of age with acute diarrhea 1.

Persistent Symptoms Beyond 14 Days

If diarrhea persists for 14 days or more despite probiotic therapy:

• Reassess for non-infectious conditions including inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) 1
• Reevaluate fluid and electrolyte balance and nutritional status 1
• Consider testing for lactose intolerance 1
• Do not prescribe additional antibiotics for persistent nonspecific symptoms following standard Lyme disease treatment who lack objective evidence of reinfection 4

Common Pitfalls to Avoid

• Do not use rifaximin for antibiotic-associated diarrhea—it is FDA-approved only for travelers' diarrhea caused by noninvasive E. coli, hepatic encephalopathy, and IBS-D, not for antibiotic-associated diarrhea 2
• Do not prescribe prolonged or repeated courses of antibiotics for persistent post-treatment symptoms, as this represents dysbiosis rather than active infection and will worsen the microbiome disruption 4
• Do not dismiss the possibility of CDI based on timing alone—it can occur weeks to months after antibiotic exposure 2
• Do not use probiotics in immunocompromised patients without careful consideration of bacteremia risk 1