Table 2.
Summary of studies culturing small bowel microbiome
| Study | Number of patients | Sample type | Microbiology results | Comments |
| Drasar and Shiner76 | 13 Diarrhoea, all investigations negative | Jejunal capsule | No difference from controls; no increased numbers of pathogens or non-pathogens | Possible IBS but not defined as IBS |
| Rumessen et al 77 | 60 Patients suspected of SIBO | Proximal jejunal aspirate | 15 With no predisposing cause had no evidence of SIBO; of 23 with SIBO, 4 had no predisposing cause | Groups poorly defined, 8 IBS identified and all negative for SIBO; 22 cases considered inconclusive |
| Corazza et al 78 | 31 Chronic diarrhoea, no predisposing cause | Proximal jejunal aspirate | 10 Had SIBO (≥106 cfu/ml or colonic bacteria), 2 IBS, 8 other multiple other diagnoses | IBS not defined, and total IBS not clear |
| Bardhan et al 79 | 10 Controls; 4 irritable colon; 22 other | Endoscopic aspirates from proximal jejunum | No positive cultures in irritable colon | Positive cultures in 11 cases, many postsurgical |
| Lewis et al 80 | 23 With functional bowel disorders | Duodenal endoscopic aspirate | Mean control count 3.2×102 cfu/ml, no anaerobes, no sterile samples | No specific IBS, defined as functional bowel disorders |
| Sullivan et al 81 | 7 IBS; 20 controls | Proximal jejunal biopsy using Watson capsule | No differences, flora similar to normal oropharyngeal flora | Colonic pathogen in 2 healthy subjects |
| Posserud et al 82 | 162 IBS; 42 controls | Proximal jejunal aspirate | 4%≥105 cfu, same as controls. Subanalysis using ≥5×103, 43% IBS vs 12% controls | No correlation with motor pattern in IBS group |
| Kerckhoffs et al 83 | 8 IBS; 9 controls | Proximal jejunal aspirate | No different number diagnosed with SIBO using multiple definitions | No differences also using molecular-based counts |
| Choung et al 84 | 148 IBS; 542 ‘other indications to test for SIBO’ | Duodenal endoscopic aspirate | 2% IBS >105 cfu/ml 10% in ‘other’ indications | Retrospective study 18% IBS >0<105 cfu/ml |
| Pyleris et al 85 | 85 IBS 150 non-IBS | Duodenal endoscopic aspirate | 37% IBS >103 cfu/ml 15.11% non-IBS | All investigated because of UGI bleed |
IBS, irritable bowel syndrome; SIBO, small intestinal bacterial overgrowth; UGI, upper gastrointestinal.