RESUMEN
The different bacterial species that were isolated from human renal stones: Pseudomonas aerugniosa [urease +ve], Proteus mirabilis, Citrohacler freundii, Klebsiella pneumonia, Staphylococcus aureus, Pseudomonas aeruginosa, [urease -ve], and Escherichia coli, succeeded in stone formation in rats' kidneys, this was determined by examining tissue sections of the kidneys. However, urease producing bacteria revealed more severe than non-urease ones, which influenced, markedly, in increasing urine volume after 10 days of bacterial injecting followed by a decline after 20 - 30 days, however, pH was acidic during the first ten days of injection, changed to alkalinity later, whereas those had been injected with non-urease producers, did not show such changes in their urine.