Pathogen detection in blood and other clinical samples

For molecular infection diagnosis, conventional DNA isolation from blood generates a mixture of human DNA and pathogen DNA. A problem with this approach is the possibility that bacteria-specific primers, including universal 16S or 23S rDNA primers, bind to unspecific sequences on the human DNA. In particular, with high human to bacterial (target) DNA ratios, i.e. at very low pathogen numbers, unspecific primer binding can lead to a loss in sensitivity and specificity of detection (1, 2).

Molzym has developed a new technology, MolYsis, for the nearly quantitative removal (>99%) of human non-target DNA from whole blood. MolYsis is available as kits in various configurations enabling the removal of human DNA from blood and other primary body fluids and cultured blood. MolYsis is a simple procedure that precedes DNA isolation.

Human cells are lysed by a chaotropic buffer thereby releasing the DNA. Subsequently, the DNA is degraded by added MolDNase, an endonucleolytic enzyme resistant against chaotropes. At the end, pathogen cells are sedimented, washed and treated with BugLysis, a reagent degrading the cell walls of Gram-positive and Gram-negative bacteria, together with a proteinase K treatment for complete lysis. Thereafter, bacterial DNA is isolated by a bind-wash-elute procedure, either using kits of other suppliers or Molzym's MolYsis Complete5 kits.