Response to Lange re: Calcium Oxalate Urolithiasis: A Case of Missing Microbes? by Batagello et al. (From: Lange D. J Endourol 2018;32:1006;DOI: 10.1089/end.2018.0606)

The role of Oxalobacter formigenes in maintaining the overall oxalate homeostasis is unquestionable. Numerous studies from multiple animal species have consistently shown that the relative abundance of O. formigenes increases in the gut, when exposed to dietary oxalate. ^{1 –3} In addition, and as reported in the original article, oral administration of O. formigenes reduces urinary oxalate, at least ephemerally. ^{4 –8} However, our meta-analysis of the data clearly reveals that O. formigenes is not a good predictor of either urinary oxalate excretion or risk for calcium oxalate stone formation in humans. Rather the data point to the ongoing importance of the microbiome as a whole instead of single bacterial species. The bacterial network working together to maintain oxalate homeostasis is the puzzle we need to unravel. Research focused on the impact of the human microbiome as a whole on urinary stone disease is promising. This work may ultimately lead to more effective and persistent bacteriotherapy options than those focused on a single species. The gut microbiota harbored by the human gut are not only simple residents of our bodies, but also they work for us contributing to our health. The future is bright!