Effects of diverse materials-based methods on DNA extraction for Clostridium difficle from stool samples

Nosocomial infections, including Clostridium difficile infection (CDI), and their fatality rates have increased in the past few decades. Despite emerging molecular diagnostic technologies with rapid, accurate outcomes, nucleic acid extraction from stool samples remains the first limiting step before downstream applications. Commercial nucleic acid extraction kits greatly decrease labor and time requirements, and also provide nucleic acid preparations with higher quality and purity for enzyme digestion analysis or genotyping. The magnetic bead based technique is a novel method compared with the conventional spin-column method, and currently has widespread use in nucleic acid extraction. We evaluated five DNA extraction kits with magnetic beads using materials with various properties (particle size, concentration of magnetic beads, grinding beads) and reagents (proteinase K, lysozyme, isopropanol, and absolute ethanol) to determine the cost, hands-on time, number of essential operations, and quality and purity of the DNA preparations, compared with those obtained using the QIAamp Fast DNA Stool Mini Kit. The six DNA extraction kits yielded A260/280 ratios ranging from 0.85 to 1.9 (average 1.57), and concentrations from 3.70 to 108.09 ng/μL (average 34.64 ng/μL). All the DNA samples had acceptable downstream application effects, except for those obtained using the TIANGEN Magnetic Soil and Stool DNA Kit. However, gel electrophoresis analysis of the DNA samples resulted in a light strip on the gel, indicating that the proteinaceous contaminant may not have been removed completely. A rapid and accurate molecular diagnostic technique could allow for more suitable treatment and prognosis outcomes for inpatients, depending, in large part, on the quality and purity of DNA preparations, which are frequently neglected. Our study focused on the quality of commercial kits with a primary focus on the treatment of stool samples and molecular diagnostic applications.