DNA microarray-based identification of bacterial and fungal pathogens in bloodstream infections

The accurate and rapid identification of pathogens in blood is a major challenge in clinical pathogen diagnostics because of the high mortality of sepsis. Here we report the development of DNA microarray for the identification of pathogens causing bloodstream infections. Species-specific and bacteria- and fungi-broad-ranged probes were designed to identify 50 bacteria and 7 fungi. The specificities and sensitivities of the selected probes were successfully validated by applying reference strains. To assess the performance of the DNA microarray in a clinical setting, blind tests were performed using 112 blood culture specimens that showed preliminary presence of pathogenic microorganisms by culture-based method, resulting in the correct identification of pathogens in 104 samples showing the sensitivity of 93%. In addition, closely-related species could be discriminated by the distinct hybridization patterns. This DNA microarray-based pathogen diagnosis takes approximately 10 h starting from a positive blood culture, considerably reducing time required to sufficiently identify pathogens by subsequent agar-culture and biochemical tests which requires altogether at least 1-3 days. Also, the amount of sample required for the identification of pathogens is much less than that required for biochemical assays. Thus, the DNA microarray reported here should be useful for the effective identification of microbial pathogens in blood cultures from septicemic patients.