Methods, devices and compositions for diagnosing, predicting and monitoring a urinary tract infection in a subject are described. The present invention also relates to a novel process for preparing the sulfonic acid metal cation salts and to a novel process for preparing aldehydes of the formula 2from the corresponding sulfonic acid metal cation salts. The compression elements are arcuate in shape and joined at the ends. A preload mechanism is positioned to bias the second surfaces of the abrasive member toward the substrate surface.