Table 2

Summary of studies culturing small bowel microbiome

StudyNumber of patientsSample typeMicrobiology resultsComments
Drasar and Shiner76 13 Diarrhoea, all investigations negativeJejunal capsuleNo difference from controls; no increased numbers of pathogens or non-pathogensPossible IBS but not defined as IBS
Rumessen et al 77 60 Patients suspected of SIBOProximal jejunal aspirate15 With no predisposing cause had no evidence of SIBO; of 23 with SIBO, 4 had no predisposing causeGroups poorly defined, 8 IBS identified and all negative for SIBO; 22 cases considered inconclusive
Corazza et al 78 31 Chronic diarrhoea, no predisposing causeProximal jejunal aspirate10 Had SIBO (≥106 cfu/ml or colonic bacteria), 2 IBS, 8 other multiple other diagnosesIBS not defined, and total IBS not clear
Bardhan et al 79 10 Controls; 4 irritable colon; 22 otherEndoscopic aspirates from proximal jejunumNo positive cultures in irritable colonPositive cultures in 11 cases, many postsurgical
Lewis et al 80 23 With functional bowel disordersDuodenal endoscopic aspirateMean control count 3.2×102 cfu/ml, no anaerobes, no sterile samplesNo specific IBS, defined as functional bowel disorders
Sullivan et al 81 7 IBS; 20 controlsProximal jejunal biopsy using Watson capsuleNo differences, flora similar to normal oropharyngeal floraColonic pathogen in 2 healthy subjects
Posserud et al 82 162 IBS; 42 controlsProximal jejunal aspirate4%≥105 cfu, same as controls. Subanalysis using ≥5×103, 43% IBS vs 12% controlsNo correlation with motor pattern in IBS group
Kerckhoffs et al 83 8 IBS; 9 controlsProximal jejunal aspirateNo different number diagnosed with SIBO using multiple definitionsNo differences also using molecular-based counts
Choung et al 84 148 IBS; 542 ‘other indications to test for SIBO’Duodenal endoscopic aspirate2% IBS >105 cfu/ml 10% in ‘other’ indicationsRetrospective study 18% IBS >0<105 cfu/ml
Pyleris et al 85 85 IBS 150 non-IBSDuodenal endoscopic aspirate37% IBS >103 cfu/ml 15.11% non-IBSAll investigated because of UGI bleed
  • IBS, irritable bowel syndrome; SIBO, small intestinal bacterial overgrowth; UGI, upper gastrointestinal.