Kidney Week

Abstract: TH-PO1117

Ciprofloxacin Overdose-Associated Crystal Nephropathy: Ultrastructural Evidence from Electron Microscopy

Session Information

• Pathology and Lab Medicine
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pathology and Lab Medicine

• 1700 Pathology and Lab Medicine

Authors

• Kataoka, Tomoka, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan

Tomoka Kataoka

• Aoyagi, Izumi, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan

Izumi Aoyagi, MD

• Shimogawa, Maiko, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan

Maiko Shimogawa

• Tanaka, Rina, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan

Rina Tanaka, MD

• Ikeda, Mari, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan

Mari Ikeda, MD

• Ohara, Mamiko, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan

Mamiko Ohara, MD, PhD, FASN

• Suzuki, Tomo, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan

Tomo Suzuki, MD, PhD

Introduction

In recent years, crystal-induced nephropathy has gained increasing attention as a form of drug-induced kidney disease. However, crystal deposition is rarely confirmed by kidney biopsy. We report a case of ciprofloxacin-induced crystal nephropathy in which intratubular crystals were identified by electron microscopy.

Case Description

A 59-year-old man with a history of hypertension and chronic kidney disease. Twenty days prior to admission, he developed fever and shaking chills and was evaluated at a local clinic. He was started on ciprofloxacin (CPFX) at 800 mg/day (serum creatinine [Cr], 2.09 mg/dL; eGFR, 27 mL/min/1.73 m2). Blood cultures later revealed Klebsiella pneumoniae bacteremia, and the CPFX dose was increased to 1200 mg/day (Cr, 1.48 mg/dL; eGFR, 40 mL/min/1.73 m2). He completed 14 days of antibiotic therapy.
However, two days prior to presentation, laboratory testing revealed a marked increase in serum creatinine to 12.17 mg/dL. After admission, he was diagnosed with a liver abscess and started on ampicillin/sulbactam at 3 g/day. Because of limited improvement in kidney function, a kidney biopsy was performed.
Light microscopy revealed tubular epithelial cell injury with vacuolar degeneration without tubulitis. No significant glomerular abnormalities were observed. Immunofluorescence studies showed no abnormalities. Electron microscopy demonstrated needle-shaped crystalline structures (Figure) and giant mitochondria within tubular epithelial cells.
Based on these findings and the clinical course, the diagnosis was consistent with acute tubular injury secondary to ciprofloxacin-associated crystal-induced nephropathy. After discontinuation of ciprofloxacin, kidney function gradually improved.

Discussion

Ciprofloxacin is a fluoroquinolone antibiotic primarily excreted by the kidneys; therefore, dose adjustment according to kidney function is essential. Although ciprofloxacin-associated crystal-induced nephropathy due to overdose has been suggested, this case is valuable in that crystal deposition was demonstrated by electron microscopy.