title: The effect of a multispecies probiotic mixture on the symptoms and fecal microbiota in diarrhea-dominant irritable bowel syndrome: a randomized, double-blind, placebo-controlled trial.
abstract: BACKGROUND
  The clinical effect of probiotics on irritable bowel syndrome (IBS) is still controversial.
  
  
  OBJECTIVE
  We aimed to evaluate the effects of a probiotic mixture on IBS symptoms and the composition of fecal microbiota in patients with diarrhea-dominant IBS (D-IBS).
  
  
  METHODS
  Fifty patients with D-IBS were randomized into placebo or probiotic mixture (Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Bifidobacterium breve, Bifidobacterium lactis, Bifidobacterium longum, and Streptococcus thermophilus 1.0×10 CFU) groups. Treatment was taken daily for 8 weeks. The primary outcome was adequate relief (AR) of overall IBS symptoms, which was assessed weekly for 10 weeks. A responder was defined as a patient who experienced AR for at least half of the 10-week study period. Secondary outcomes included the effects on individual symptoms, stool parameters, and IBS quality of life. The fecal flora compositions were analyzed by polymerase chain reaction denaturing gradient gel electrophoresis (DGGE).
  
  
  RESULTS
  The proportion of AR was consistently higher in the probiotics group than in the placebo group throughout the 10-week period (P<0.05). The proportion of responders was significantly higher in the probiotics group than in the placebo group (48% vs. 12%, P=0.01). Stool consistency improved significantly in the probiotics group compared with the placebo group. Percent changes in individual symptom scores were similar in the 2 groups, but IBS quality of life improvement tended to be higher in the probiotics group. Comparison of denaturing gradient gel electrophoresis profiles of fecal flora showed that the concordance rate between bacterial compositions before and after treatment was significantly higher in the probiotics group than in the placebo group (69.5% vs. 56.5%, P=0.005).
  
  
  CONCLUSIONS
  The probiotic mixture was effective in providing AR of overall IBS symptoms and improvement of stool consistency in D-IBS patients, although it had no significant effect on individual symptoms. The therapeutic effect of probiotics is associated with the stabilization of intestinal microbiota.
authors.affiliation: Department of Internal Medicine, Chung-Ang University College of Medicine, Republic of Korea.
authors.forename: Bong
authors.initials: B
authors.lastname: Ki Cha
authors.forename: Seung
authors.initials: S
authors.lastname: Mun Jung
authors.forename: Chang
authors.initials: C
authors.lastname: Hwan Choi
authors.forename: In-Do
authors.initials: ID
authors.lastname: Song
authors.forename: Hyun
authors.initials: H
authors.lastname: Woong Lee
authors.forename: Hyung
authors.initials: H
authors.lastname: Joon Kim
authors.forename: Jae
authors.initials: J
authors.lastname: Hyuk
authors.forename: Sae
authors.initials: S
authors.lastname: Kyung Chang
authors.forename: Kijeong
authors.initials: K
authors.lastname: Kim
authors.forename: Won-Seok
authors.initials: WS
authors.lastname: Chung
authors.forename: Jae-Gu
authors.initials: JG
authors.lastname: Seo
mesh_terms: D000328:Adult; D001644:Bifidobacterium / Q000145:classification / Q000502:physiology; D003967:Diarrhea / Q000382:microbiology / Q000503:physiopathology / Q000628:therapy*; D004311:Double-Blind Method; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000382:microbiology / Q000503:physiopathology* / Q000628:therapy*; D007778:Lactobacillus / Q000145:classification / Q000502:physiology; D007779:Lactobacillus acidophilus / Q000502:physiology; D008297:Male; D008875:Middle Aged; D019936:Probiotics / Q000145:classification* / Q000627:therapeutic use*; D012720:Severity of Illness Index; D013045:Species Specificity; D048249:Streptococcus thermophilus / Q000502:physiology; D016896:Treatment Outcome; D055815:Young Adult