Rapid parallelized and quantitative analysis of five pathogenic bacteria by ITS hybridization using QCM biosensor

We developed a 2×5 model quartz crystal microbalance (QCM) DNA biosensor array for detection of five bacteria, which based on hybridization analysis of bacterial 16S–23S rDNA internal transcribed spacer (ITS) region. A pair of universal primers was designed for PCR amplification of the ITSs. The PCR products were analyzed by the biosensor. We used gold nanoparticles to amplify the frequency shift signals. Fifty clinical samples were detected by both the biosensor and conventional bacteria culture method. We found a linear quantitative relationship between frequency shift and logarithmic concentration of synthesized oligonucleotides or bacteria cells. The measurable concentration ranged from 10−12 to 10−8M for synthesized oligonucleotides and 1.5×102 to 1.5×108CFU/mL for bacteria. The 10−12M of synthesized oligonucleotides or 1.5×102CFU/mL of Pseudomonas aeruginosa could be detected by the biosensor system. The detection could be completed within 5h including the PCR amplification procedure. Compared with bacteria culture method, the detection sensitivity and specificity of the biosensor system were 94.12% and 90.91%, respectively. There was no significant difference between these two methods (P=0.625>0.05). The biosensor system provides a rapid and sensitive method for parallelized and quantitative analysis of multiple pathogenic bacteria in clinical diagnosis.