Combination Probiotic: BB-12 With LGG (Different Doses) in Treating Children With Autism Spectrum Disorder

Inclusion Criteria: * Healthy children with autism spectrum disorders (4 - 16 years old) and gastrointestinal symptoms, based on the GI Severity Index, with no other recognized illness will be enrolled in this study. There will be no selection on the basis of age, race, or gender. Although the investigators anticipate the majority of subjects will be male and/or pre-pubertal, in females of childbearing potential, a pregnancy test (urine) will be performed on females participating (at each visit). Exclusion Criteria: * Pregnancy or breastfeeding * Subjects taking immunosuppressive medications, including oral corticosteroids * A History of Positive result of HIV, Hepatitis B, and/or Hepatitis C test * Abnormal lab test results (Section 5.2) * Gastrointestinal diseases such as celiac disease, inflammatory bowel disease * Subjects with an allergy to antibiotics * Presence of fever or a pre-existing adverse event monitored in the study * Use of probiotics in the last 30 days * Acute diarrheal illness within the past 30 days * Recent (within 2 weeks) or current use of oral antibiotics /anti-fungals Current use of oral laxatives * Subjects with implanted prosthetic devices including prosthetic heart valves * The investigators will require that subject not take any other probiotic-containing products, including yogurt supplemented with probiotics during the study period.