We explore a new laboratory technique in the field of urinalysis promising a combination of speed and selectivity in support of urinary tract infection diagnosis. Laboratory experimentation demonstrates long range surface plasmon polaritons (LRSPP) waveguides as a useful biosensor to selectively detect gram negative bacteria or gram positive bacteria in human urine. The biosensor can detect bacteria at concentration of 105 CFU/ml, the internationally recommended threshold for diagnostic of urinary tract infection (UTI). Using a negative control solution at bacterial concentration 1000x higher than the targeted bacteria in urine with a weak concentration of constituents, the power ratio between the negative control signals to the target bacteria signal is measured to be 5.4. Thus we report a conclusive demonstration of the LRSPP waveguide biosensor selectivity to the gram of bacteria in human urine. In addition, the biosensor may prove useful as an alternative urinalysis test method to determine the urine specific gravity, to estimate proteinuria, and to detect biofilm formation on surfaces.