Small Intestinal Bacterial Overgrowth: What It Is and Isn't
Small Intestinal Bacterial Overgrowth: What It Is and Isn't
Two clinical scenarios may be encountered that may involve SIBO. The first, which may be regarded as classical SIBO, refers to the situation in which clinical features can be pathophysiologically linked with SIBO; affected patients typically present with features of malabsorption and/or maldigestion. Here the diagnostic and therapeutic approaches have been rather well developed and, to some degree, validated. In this more restricted concept of SIBO, culture of jejunal fluid remains a valuable benchmark as abnormal results correlate well with such clinical and pathological consequences as steatorrhea and anemia. The second relates to the patient with no overt evidence of malabsorption/maldigestion in whom symptoms have been linked to SIBO. Here it is clear that we do not have validated criteria for the incrimination of SIBO as the accuracy of all current tests remains limited in this context. When we extend the concept of SIBO into these areas, we are bereft of a gold standard and issues such as the clinical implications of lower levels of contamination and distal overgrowth come into play; these issues are unresolved. From a clinical perspective, only a full clinical response to a course of appropriate antibiotics can satisfy the clinician that SIBO is the villain but here, again, effects on the colonic flora may complicate interpretation. Modern genomic and metabolomic techniques offer much promise in defining true normality and then fully identifying alterations in the flora in disease states; we look forward to their application to the diagnosis and management of SIBO.
Conclusion
Two clinical scenarios may be encountered that may involve SIBO. The first, which may be regarded as classical SIBO, refers to the situation in which clinical features can be pathophysiologically linked with SIBO; affected patients typically present with features of malabsorption and/or maldigestion. Here the diagnostic and therapeutic approaches have been rather well developed and, to some degree, validated. In this more restricted concept of SIBO, culture of jejunal fluid remains a valuable benchmark as abnormal results correlate well with such clinical and pathological consequences as steatorrhea and anemia. The second relates to the patient with no overt evidence of malabsorption/maldigestion in whom symptoms have been linked to SIBO. Here it is clear that we do not have validated criteria for the incrimination of SIBO as the accuracy of all current tests remains limited in this context. When we extend the concept of SIBO into these areas, we are bereft of a gold standard and issues such as the clinical implications of lower levels of contamination and distal overgrowth come into play; these issues are unresolved. From a clinical perspective, only a full clinical response to a course of appropriate antibiotics can satisfy the clinician that SIBO is the villain but here, again, effects on the colonic flora may complicate interpretation. Modern genomic and metabolomic techniques offer much promise in defining true normality and then fully identifying alterations in the flora in disease states; we look forward to their application to the diagnosis and management of SIBO.