Bacteremic kidney cyst infection caused by Helicobacter cinaedi

Cyst infection is one of the major complications in patients with autosomal dominant polycystic kidney disease (ADPKD). The causative pathogen in kidney cyst infection frequently goes undetected. Although only one case report of kidney cyst infection caused by Helicobacter cinaedi (H. cinaedi) is published in English literature, it may be an important pathogen in kidney cyst infection. Kidney cyst infection and H. cinaedi infection share the common characteristic of tendency to relapse and chronic kidney disease is a major risk factor for H. cinaedi infection. Moreover, a long period is required to detect H. cinaedi in blood cultures, potentially causing false-negative results. After the identification of H. cinaedi, we must carefully select antibiotics and the antibiotic treatment period should be extended to prevent recurrence. Here we present a case of a 58-year-old male with ADPKD who developed bacteremic kidney cyst infection caused by H. cinaedi. He was admitted to our hospital because of fever, lower left back pain, vomiting, and feeling of abdominal enlargement. H. cinaedi was detected from the blood cultures obtained at admission after 4 days of culture. Antibiotics were administered for 8 weeks after confirming negative blood cultures. There was no evidence of kidney cyst infection relapse at 3 months after treatment completion. Nephrologists should regard H. cinaedi as a challenging but important pathogen in kidney cyst infection, particularly when the causative organism is unknown or kidney cyst infection is recurrent.