Does Weight Loss Surgery and Probiotic Supplementation Lead to a "Lean" Gut Microbiota?

Inclusion criteria

• Age greater than or equal to 18 years
• Able to give informed consent and report on side effects
• Tolerating an oral/enteral diet
• Stable comorbid conditions
• Outpatient

Exclusion criteria

• Inpatients
• Pregnancy (urine test done on all patients routinely pre-op)/ unwilling to comply with contraceptive requirement after gastric bypass surgery
• Known use of LGG or another probiotic (not including yogurt) within the previous 30 days
• Presence of an active bowel leak, acute abdomen, active intestinal disease, or significant bowel dysfunction
• Presence of an absolute neutrophil count less than 500 per cubic mm (must have had a Complete Blood Count within the last 6 months) or anticipation post chemotherapy that the absolute neutrophil count will fall below 500 per cubic mm.
• History of adverse reaction to product containing lactobacillus
• Active colitis (*see definition below)
• Known or suspected allergies to probiotics, lactobacillus, milk protein, or microcrystalline cellulose
• Structural heart disease, history of endocarditis or valve replacement, implanted cardiac device, congestive heart failure
• Positive baseline stool culture for LGG
• Recent or planned chemotherapy or radiation therapy
• Solid organ transplant within the prior year
• Stem cell transplant within the prior year
• On active immunosuppressive medication [anti-rejection, injectable immunosuppressive drugs for autoimmune disease, or corticosteroids (greater than ½ mg per kg body weight of prednisone or its equivalent) not including inhaled or topical steroids]
• Allergy or intolerance to or contraindication to two or more of the rescue antibiotic regimens (ampicillin, clindamycin, moxifloxacin)
• Participating in another clinical trial
• Uncontrolled psychiatric illness