Struvite Stone Formation by Ureolytic Biofilms

This chapter describes the role ureolytic biofilms (communities of microbes attached to surfaces) play in struvite stone formation in the urinary tract. The formation of struvite stones (MgNH4PO4·6H2O), commonly known as infection stones, is associated with urinary tract infections, particularly, with ureolytic microorganisms. Establishment of ureolytic biofilms in the urinary tract can result in increased microbial resistance to medical treatment and development of the necessary urine conditions to promote struvite (or other mineral) precipitation possibly leading to stone formation. Ureolytic microorganisms produce urease, an enzyme that breaks down urea (CO(NH2)2) generating ammonium (NH4+) and alkalizing urine, which changes urine chemistry to potentially promote struvite and other mineral precipitation. This chapter describes the series of steps involved in biofilm development and struvite precipitation leading to stone formation. Furthermore, this chapter presents an overview of controlled laboratory experiments and computer simulations currently used in different disciplines to study microbe-fluid-mineral interactions. We conclude that an interdisciplinary approach including the disciplines of engineering, mathematics, chemistry, microbiology and medicine will provide a more comprehensive understanding of the process of stone formation in the urinary tract and will ultimately allow for the development of improved management and prevention strategies for infection stones.