AUA 2018: Evaluation of Bacterial Biofilms on Renal Calculi

San Francisco, CA USA ( Negar Motayagheni, MD, from the Wake Forest School of Medicine, presented data regarding the relevance of bacterial biofilms on and in renal calculi and urine culture to establish a cause for sepsis. He prefaced his research by stating bacterial biofilms have been found anchored on indwelling medical devices and in UTIs. Motayagheni hypothesized that the presence and aggregation of bacteria on uroliths can be a cause for sepsis.

A total of 23 patients were surveyed and followed prospectively. Percutaneous nephrolithotomy was used for the extraction of renal stones before they were sterilized with ethanol. The stones were then crushed to determine the presence of the bacteria inside the calculi. MALDI-TOF mass spectrometry identified bacterial species while scanning electron microscopy (SEM) provided insight to morphological features. Each patient’s urine cultures and antibiotic therapies within 30 days before and after the procedure were reviewed.

Eight urine samples tested positive for bacteria while nine stone cultures confirmed gram negative pathogens. Of the nine positive stone cultures, only seven revealed bacterial aggregation detected by microscopy. Interestingly, four of the nine patients with positive stone cultures were maintained on antibiotics the month prior to stone extraction. Urine tests were negative in four patients even with infected calculi. Of the positive results, only one patient had a positive renal calculi and urine culture which was similar to E. coli.

In conclusion, Dr. Motayagheni discovered that bacteria could be found both superficially and internally within renal calculi. However, the study team found no relationship between the presence of bacteria on or in renal calculi and urine culture and therefore, bacteria on or in the renal calculi and sepsis.

Presented by: Negar Motayagheni, MD

Written by: Ruchita Patel, Department of Urology, University of California-Irvine at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA
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