WCE 2017: Microbiome of Stone Disease
The true size of the bacterial cells exceeds the human cells by roughly 10 times. Majority of these organisms are found in the intestinal track and assist our body in the breakdown of various compounds. One of these compounds is oxalate. Oxalate is readily absorbed by the intestinal tract, which is problematic as this predisposes us to the formation of calcium oxalate stones. However, a bacterium known as oxalobacter formigenes is able to digest oxalate, thus preventing it from accumulating inside our bodies.
Dr. Lange indicates that many patients lack this specialized bacterium, which predisposes them to the formation of calcium oxalate stones. In turn, probiotics were created with oxalobacter formigenes as a tool to help colonize these oxalobacter formigenes naive patients. Initial results indicated a rise of this bacterium in the intestinal flora; however this was only short lived. Dr. Lange provides an explanation for this outcome, stating that this bacterium requires highly specific growth requirements and we need to consider the symbiotic environment of the intestine.
A study has shown that increased bacteroides species is associated with an increased risk of stone formation, whereas increased prevotella species is associated with a lower stone risk. Another study on wood rats showed that increasing oxalate consumption leads to increase oxalate breakdown. Based on these findings, Dr. Lange said that oxalobacter formigenes is not the sole player in the breakdown of oxalate, but instead that there exists an Oxalobacter network, and that non-stone formers have a more robust and extensive network.
From his talk, Dr. Lange concludes that the intestinal microbiome has a definite role in recurrent kidney stone disease. Initially this role was restricted to oxalobacter formigenes, but recent evidence strongly suggests that the maintenance of a healthy oxalate homeostasis involves multiple bacterial species (Oxalobacter Network) working symbiotically to form an oxalate microbiome.
Presented by: Dirk Lange, PhD
Plenary Chairs: John Denstedt, MD, FRCSC, FACS, FCAHS, Margaret Pearle, MD, PhD,
Affiliation: University of British Columbia, Division of Urology, Western University, London, Ontario, Canada, Department of Urology, UT Southwestern
Written by: Egor Parkhomenko, Department of Urology, University of California-Irvine at 35th World Congress of Endourology– September 12-16, 2017, Vancouver, Canada.