Cyst infection in autosomal dominant polycystic kidney disease: our experience at Toranomon Hospital and future issues

Cyst infection is a frequent and serious complication of autosomal dominant polycystic kidney disease (ADPKD) that is often difficult to treat and can be fatal. However, much is still unknown about cyst infection. Positron emission tomography (PET) is generally recommended for detecting infected cysts, but it has the disadvantages of limited availability, high cost, and radiation exposure. We have devised magnetic resonance imaging (MRI) diagnostic criteria for cyst infection. Lipid-soluble antibiotics such as fluoroquinolones show good penetration into cysts and are recommended for cyst infection. However, we reported that fluoroquinolone-resistant microorganisms showed a high prevalence in cyst infection. We should, therefore, reconsider the empirical use of fluoroquinolones for ADPKD patients with cyst infection. We have suggested a new antibiotic strategy according to the severity of cyst infection. It may be important to consider the drug half-life in serum in addition to the drug susceptibility when selecting antibiotics Cyst drainage is necessary for some patients with refractory cyst infection; however, cyst drainage can be associated with severe adverse events. We suggest adaptation criteria for cyst drainage in patients with cyst infection in ADPKD. Most causative bacteria of cyst infection are enterobacteria, and hematogenous spread via bacterial translocation in the intestine is considered the main cause of cyst infection. Therefore, intestinal flora may be important for cyst infection. The role of the intestinal flora in cyst infection in ADPKD is unknown and should be explored in future research.