Table 2.
Bariatric surgery clinical trials.
| Study identification | Description | N | Population description | Outcomes |
|---|---|---|---|---|
| Palleja et al. 2016 [36] | Longitudinal observational study | 13 | Participants were recruited for bariatric surgery: BMI > 40 kg/m2 or BMI > 35 kg/m2 with T2D/hypertension | Gut microbial diversity increased within the first 3 months after RYGB and remained high 1 year later. RYGB led to altered relative abundances of 31 species: Escherichia coli, Klebsiella pneumoniae, Veillonella spp., Streptococcus spp., Alistipes spp., and Akkermansia muciniphila. |
| Fecal samples | ||||
| Quantification of gut microbiomes at baseline (n = 13), 3 months (n = 12) after RYGB, and 12 months (n = 8) after RYGB | ||||
| 16S rDNA shotgun sequencing | ||||
|
| ||||
| Tremaroli et al. 2015 [29] | Clinical trial | 21 | Weight-stable women 9 years after randomization to either RYGB or LSG and matched for weight and fat mass loss Control: 2 groups of nonoperated women with BMI matched to patients' (1) presurgical BMI and (2) postsurgical BMI |
Significant differences in microbiota composition for RYGB versus OBS samples but not for LSG versus OBS or RYGB versus LSG. 29 microbial genera differed significantly between RYGB and controls: ↑ Gammaproteobacteria class and ↓ three species in the Firmicutes phylum (C. difficile, C. hiranonis, and G. sanguinis). At the genus level: ↑ Proteobacteria (Escherichia, Klebsiella, and Pseudomonas) in RYGB. No different microbiota profiles for RYGB and LSG patients. |
| Fecal samples | ||||
| 16S rDNA | ||||
| Illumina HiSeq 2000 | ||||
| Shotgun sequencing | ||||
|
| ||||
| Damms-Machado et al. 2015 [34] | Clinical trial | 10 | 10 unrelated subjects with obesity grade III at 3 time points: (1) baseline (2) 3 months after LSG (3) 6 months after LSG (N = 5) or dietary weight loss regimen (N = 5) |
Both interventions resulted in changes of the B/F ratio but with an inverse relationship between the main phyla. LSG: ↑ Bacteroidetes and ↓Firmicutes Dietary intervention: ↓ Bacteroidetes and ↑Firmicutes In LSG: Bacteroidetes correlated negatively with weight. Firmicutes positively correlated with weight. |
| Fecal samples | ||||
| SOLiD long-mate-paired shotgun sequencing | ||||
|
| ||||
| Graessler et al. 2013 [37] | Clinical trial | 6 | 3 men and 3 women, recruited for RYGB 38–53 years Preoperative BMI 40.9–52.1 |
↓ Firmicutes, Bacteroidetes, Actinobacteria, and Cyanobacteria. However, the ratios of B/F shifted from 0.99 to 1.31, showing an apparent increase. ↑ Proteobacteria, Verrucomicrobia, and Fusobacteria. 3 months after RYGB, ↑ E. cancerogenus, Veillonella parvula, V. dispar, Shigella boydii, and Salmonella entérica. Postoperative abundances of these species were also significantly higher than those in lean controls. |
| Fecal samples | ||||
| 16S rDNA | ||||
| Illumina HiSeq 2000 | ||||
| Shotgun sequencing | ||||
BMI: body mass index, expressed as kg/m2; RYGB: Roux-en-Y gastric bypass; LSG: sleeve gastrectomy.