Calcified bacteria in renal stones: electron-microscopic aspects

Area of Science:

• Nephrology
• Microbiology
• Materials Science

Background:

• Renal calculi (kidney stones) are complex structures.
• The role of bacteria in kidney stone formation is debated.
• Calcium phosphates are common components of renal calculi.

Purpose of the Study:

• To investigate the presence and morphology of bacteria within renal calculi.
• To determine if bacterial remnants contribute to the structure of kidney stones.

Main Methods:

• Analysis of renal calculi using thin section microscopy.
• Examination with transmission electron microscopy (TEM).
• Imaging with scanning electron microscopy (SEM).

Main Results:

• Rods resembling bacteria were observed within defective apatite calcium phosphate renal calculi.
• TEM revealed partially calcified bacterial structures.
• SEM provided images of bacterial impressions, not intact bacteria.
• Bacteria were rarely found in struvite stones, suggesting incompatibility with high ammonium environments.

Conclusions:

• Bacterial remnants, particularly partially calcified forms, are present in certain types of renal calculi.
• These findings suggest a potential role for bacteria in the formation of apatite calcium phosphate stones.
• High ammonium concentrations may inhibit bacterial preservation in struvite stones.