Detection of bacteria by hybridization of rRNA with DNA-latex and immunodetection of hybrids.

A novel nucleic acid hybridization assay with a DNA probe immobilized on 1.25-micron-diameter latex particles was developed. Hybridization of the immobilized probe DNA with sample rRNA was complete in 10 to 15 min. Alkaline phosphatase-labeled anti-DNA-RNA was allowed to bind to the DNA-RNA hybrids on the latex particles. Then the latex was collected on a small glass fiber filter pad, and bound alkaline phosphatase was quantitated by reflectance rate measurement. The method detected a broad range of bacterial species and had a detection limit of 500 cells per assay. The assay was used to screen urine samples for bacteriuria and had a sensitivity of 96.2% compared with conventional culture at a decision level of greater than or equal to 10(4) CFU/ml. The hybridization method could have broad application to the detection of bacteria and viruses.