Microbiome of Infected Cysts, Feces and Saliva in Patients with Autosomal Dominant Polycystic Kidney Disease: Case Reports

Background: Cyst infection is a frequent and serious complication of autosomal dominant polycystic kidney disease (ADPKD). It is often difficult to treat and can be fatal, but much is still unknown about this type of infection. Hematogenous spread via bacterial translocation in the intestine is considered to be the main cause, so intestinal flora may be involved. However, the exact role of the intestinal flora in cyst infection in ADPKD is unknown.Case presentation: We report a 66-year-old woman and a 56-year-old man with ADPKD who had severe hepatic cyst infection. We analyzed the microbiome of infected cyst content, feces, and saliva in these two patients. The microbiome of patient 1 showed various bacteria in an infected cyst, whereas that of patient 2 showed only one bacterium. In both patients, the composition of the microbiome of the cyst content was quite different from those of feces and saliva, and the main bacteria in the infected cyst content represented a small proportion of those in feces and saliva.Conclusions: Cyst infection in ADPKD can be caused by a single bacterium or multiple bacteria, and cyst content culture or blood culture may identify only some of the causative bacteria. The association between bacteria in cysts and those in feces or saliva remains uncertain, and further research on this topic is needed.