Intracellular crystallisation caused by Proteus mirabilis plays a significant role in recurrent urolithiasis

Abstract number: P1300

Torzewska A., Budzynska A., Bialczak-Kokot M., Rozalski A.

Objectives:Proteus mirabilis are the most common bacilli associated with the formation of bacteria-induced bladder and kidney stones. In 50% of cases, this is recurrent illness, which can lead to the loss of kidneys if not properly treated. Bacterial urease is the essential virulence factor in stones formation. Ammonia, produced by the enzymatic hydrolysis of urea, elevates urine pH causing a supersaturation and crystallisation of struvite and apatite. Crystals may grow intra as well as peribacterially. The aim of this work was to show that P. mirabilis bacilli can grow and form crystals inside urothelial cells. In this enviroment bacteria may be protected against antibiotic killing and thus cause persistent or recurrent infections.

Methods:P. mirabilis strains were recovered from encrusted biofilm on Foley catheter of long-term catheterised patients. The in vitro model was used to analyse intracellular growth and crystallisation. In this model human renal (HRPTEC), ureter (Hu 608) and bladder (HCV 29) epithelial cells were infected and incubated (3–72 h) in the presence of synthetic urine and amikacin to prevent extracellular bacterial growth. Number of intracellular bacteria was determined after host cells lysis by plating lysates on TSB plates. Crystallisation was determined using radioactive isotope of calcium. Crystals and bacteria were also observed by crystal violet and van Kossa method staining.

Results: It was found that P. mirabilis isolated from urinary catheter demonstrated a significant ability to adhere and penetrate normal urothelium, especially Hu 608 cell lines. These strains could multiply intracellularly within epithelial cells and were able to induce crystallisation. From 24 to 72 hours after infection a degree of crystallisation increased and it depended on the number of bacteria within host cells. This finding was confirmed by microscopy. The dark deposites of calcium salts within infected epithelial cells were observed.

Conclusion: Our results showed P. mirabilis ability to persist and form crystals inside the host cells, despite antibiotics presence. In this situation bacteria induce infection, usually chronic, which commonly results in the formation of bladder and kidney stones.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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