Immunomagnetic recovery of Chlamydia trachomatis from urine with subsequent colorimetric DNA detection

There is need for integrated systems that provide rapid and sensitive diagnosis of Chlamydia trachomatis. Here we describe for the first time that specific antibodies to a C. trachomatis surface protein can be used for magnetic recovery of bacteria directly from crude urine samples. The combination of immunomagnetic separation (IMS), where the bacterial cells are both purified and concentrated, with a colorimetric PCR assay makes the method sensitive and suitable for routine clinical screening in microtiter format. No filtrations, centrifugations, extractions, or electrophoretic techniques are required throughout the whole procedure. Using magnetic beads as the solid phase, the colorimetric detection of immobilized amplified nucleic acids (DIANA) also allow direct DNA sequencing of positive samples for more detailed analysis. Of the 27 urine samples analyzed, eight were found to be positive using this method. Only five out of these eight were determined to be positive by cell culture.