Infection-related kidney stones

Infection and stones can be associated in two ways. Stone disease can occur due to infection by an organism that expresses the urea-splitting enzyme urease (infection stones). Nephrolithiasis can also be complicated by urinary tract infection that in turn was caused by obstruction of the urinary tract by a stone and/or colonization of a pre-existing stone, in both cases by non-urease producing organisms. Although the incidence of infection stones appears to have declined over recent years in the United States, they remain a cause of significant morbidity and mortality. A strong index of suspicion is necessary to identify infection stones before they become large, damage kidneys, or lead to acute morbidity such as urosepsis. Surgery remains the mainstay of therapy for infection stones, combined with careful attention to antibiotic choice based upon appropriate culture results. Use of medical therapy alone is reserved for those relatively unusual cases in which there is a strong contraindication to surgery. Infection-related stones also require prompt recognition, often via use of non-contrast CT. Any obstruction that is present needs to be promptly relieved in order to decompress the kidney and allow the infection to be cleared by antibiotics chosen based upon culture results.