Urease Inhibitor Therapy in Infected Renal Stones
Struvite (ammonia and magnesium triplophosphate) and carbonate-apatite lithiasis is the effect of urinary infection due to ureaseproducing bacteria, such as Proteus, Providencia and Klebsiella. The splitting of urea induced by bacterial urease brings about the formation of NH3, the increase of bicarbonates and alkalinization of the urine, which leads in turn to supersaturatioin with regard to struvite and carbonate-apatite. It can be stated that formation of such calculi can only occur in the presence of ureolysis.
Treatment of these types of lithiasis, which were almost constantly prone to recurrence until recently, consists of: a) surgical removal of all stones; b) antibiotic therapy; c) administration of urease-inhibitors.
Acetohydroxamic acid (AHA) and hydroxyurea (UH) are the only clinically available drugs that can block urease activity.
In a group of 41 patients with infectious lithiasis a comparison between the two drugs was performed and the results accurately recorded.
AHA, at the daily dose of 500 mg is, in our view, the drug of choice. Its side-effects are less than following HU and its activity is greater, as far as normalization of ammoniuria and synergism or even potentiation of antibiotic therapy is concerned. The latter finding can be explained on the ground that bacterial urease and urinary ammonia formation represent important factors interfering with the sensitivity of urease producing bacteria to antibiotics.
KeywordsUrease Activity Hydroxamic Acid Urinary Infection Urinary Stone Stone Recurrence
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