Gut Microbiota

Question 1

Describe small intestinal bacterial overgrowth

Answer 1

An increase in bacteria in the small intestine, which usually has a very low bacterial load. Symptoms include chronic diarrhea, foamy or frothy stool, vomiting, foul-smelling stool, bloating, and constipation. Typical treatment includes broad-spectrum antibiotics. Pilot studies show promise with probiotic supplementation

Question 2

What criteria must an organism meet to be considered a probiotic?

Answer 2

Strain identification
Human origin
Live microorganism
Viable
Safe for human consumption
Survive proximal GI tract
Reach distal intestine and colon
Function/adhere to gut epithelial tissue
Colonize distal gut, affecting microbiome composition
Scientifically proven health benefits

Question 3

Describe the proposed mechanisms of action of probiotics

Answer 3

Colonization resistance
Intestinal barrier function maintenance
Enhancement of gut microbiome pattern
Modulation of inflammatory and immunoregulatory signaling
Increased mucin regulatory genes and mucin production
Metabolic effects (nutrient metabolism, bacteriocins, decrease luminal pH, quorum sensing)

Question 4

What is a prebiotic?

Answer 4

A selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the GI microbiota, that confer benefits upon host well-being

Question 5

What is the optimal dose and dosing schedule for probiotic and prebiotic effect?

Answer 5

Approximately 10 to the 9th power to 10 to the 12 power CFU/day for probiotic
5-20 gm/day for prebiotic. Dosing schedules vary from 1 or 2 times daily to 3-4 times per week

Question 6

When would the use of a probiotic be appropriate for a tube-fed patient with new onset diarrhea?

Answer 6

Osmotic diarrhea from feeds or medication is ruled out
Recent antibiotic use
Positive stool cultures (C. diff)
Formula has previously been well tolerated

Question 7

Describe the risk factors for Antibiotic-associated diarrhea (AAD) and C. difficile-associated disease (CDAD)

Answer 7

Most like causative antibiotics are fluoroquinolones. Other risk factors include severe illness, advanced age, presence of NG tube, provision of medications to raise gastric pH, GI surgery or manipulation, immunocompromised status, extended hospital stay.
AAD typically begins 4-9 days following antibiotic cessation, but it can occur up to 8 weeks later

Question 8

Describe the treatment for Antibiotic-associated diarrhea (AAD) and C. difficile-associated disease (CDAD)

Answer 8

Stop use of the inciting antibiotic. Typically treated with metronidazole initially with correction of fluid and electrolyte imbalance as needed. Treatment is repeated if initial treatment fails, then treated with oral vancomycin if fail again. Probiotic therapy (S. boulardii for C. diff; LGG and S. boulardii for AAD)

Question 9

How would you manage a patient with ulcerative colitis and a newly created ileal pouch who is receiving PN?

Answer 9

If patient at risk for onset of acute pouchitis and SIBO, begin daily VSL#3 immediately after surgery. Provide oral rehydration solution and a diet high in starch and low in simple sugars once oral diet is advanced

Question 10

Describe prebiotic characteristics

Answer 10

Must be resistant to gastric acidity, hydrolysis by mammalian enzymes, and GI absorption
Must be fermented in the GI tract by gut microbiota
Must be selective in the stimulation of the gut microbiota growth and/or activity that contribute to health and well-being
Simple, naturally occurring or synthetic sugars:
Inulin (chicory, leeks, onion, garlic, artichoke, asparagus)
Inulin-type fructans (oligofructose or fructooligosaccharide)
Transgalactooligosaccharides
Enzymatic synthesis based on lactose
Lactulose