The role of anaerobic bacteria in the pathogenesis of urinary tract infections.

Because of the rarity of anaerobic infections of the urinary tract and the difficulty of establishing these organisms as pathogens, anaerobic culture is not included as part of routine urine bacteriological examination. Pyuria was found during examination of a 41-year-old man with a chronic renal allograft rejection reaction. Aerobic urine cultures failed to yield any pathogens. Urine cytology demonstrated intracellular organisms that proved to be Fusobacterium nucleatum on anaerobic culture. The serotypically identical organism was isolated from a needle biopsy specimen of the renal allograft. In the presence of pyuria the finding of micro-organisms in the urine sediment that fail to grow on routine aerobic cultures should lead to examination for anaerobic bacterial infection of the urinary tract.