Table 2.

Overview of studies testing probiotics strains in CD. Note the high degree of heterogeneity in terms of probiotic formulations, duration of treatment, study design and target population (active vs. quiescent CD).

Probiotic Strain	Studied Population	Doses and Duration	Outcomes	Authors (Year)
Saccharomyces boulardii	CD patients (n = 20) suffering from diarrhea and augmented BEST index. After the first two weeks, patients randomly assigned to placebo or to S. Boulardii for additional 7 weeks, while the basic treatment was maintained.	▪250 mg t.i.d., initially for two weeks in addition to the basic treatment. ▪250 mg t.i.d. or placebo for additional 7 weeks, while the basic treatment was maintained.	Reduction in the frequency of bowel movements and in the BEST Index compared to baseline.	Plein and Hotz. (1993) [41]
Saccharomyces boulardii	CD patients (n = 32) in clinical remission (CDAI < 150) randomly treated with either mesalamine or mesalamine plus a preparation of Saccharomyces boulardii.	Six months with either mesalamine 1 g three times a day or mesalamine 1 g two times a day plus a preparation of Saccharomyces boulardii 1 g daily.	Clinical relapses as assessed by CDAI values were observed in 37.5% of patients receiving mesalamine alone and in 6.25% of patients in the group treated with mesalamine plus the probiotic agent.	Guslandi et al. (2000) [42]
Saccharomyces boulardii	CD patients (n = 165) in remission after treatment with steroids or salicylates, randomly assigned to groups given S. Boulardii or placebo.	S. Boulardii (1 g/day) or placebo for 52 weeks.	CD relapsed in 80 patients, 38 in the S boulardii group (47.5%) and 42 in the placebo group (53.2%): non-significant difference.	Bourreille et al. (2013) [43]
Escherichia coli Nissle 1917	Intestinal epithelial Caco-2 cell line infected with CD-Associated E. coli LF82.	Cells were co-infected with EcN (MOI of 10) after 3 h of monoinfection with strain LF82. After 6 h and 9 h of infection, the number of invasive bacteria was determined.	EcN showed an inhibitory effect on invasion by strain LF82.	Huebner at al. (2011) [44]
Bifidobacterium breve, Bifidobacterium longum, Lactobacillus casei	Active CD outpatients (n = 10), who failed to achieve remission with aminosalicylates and prednisolone, initiated on a symbiotic therapy, consisting of Bifidobacterium and Lactobacillus and Psyllium.	75 billion colony forming units [CFU] daily and psyllium 9.9 g daily.	▪Improved clinical symptoms with both CDAI and IOIBD scores significantly reduced ▪Not able to achieve suspension of corticosteroids or improvement in inflammatory markers.	Fujimori et al. (2007) [45]
Lactobacillus rhamnosus GG	Children with mildly to moderately active CD (n = 4) were given Lactobacillus GG.	1010 colony forming units (CFU) in enterocoated tablets twice a day for 6 months.	Significant improvement in clinical activity and intestinal permeability. Median pediatric CD activity index scores at 4 weeks 73% lower than baseline.	Gupta et al. (2000) [46]
Lactobacillus rhamnosus GG	Patients with moderate-to-active CD (n = 11) randomly assigned to receive either Lactobacillus GG or placebo.	109 CFU twice daily or placebo for six months.	No significant difference in frequency of relapses between the two groups.	Schultz et al. (2004) [47]