Modified DNA Extraction Technique for Use in Resource-Limited Settings: Comparison of Salting Out Methods versus QIAamp Blood Mini Kit

Background: It is essential that methods for genomic DNA extraction techniques produce high yield and purified DNA. Commercially available DNA extraction kits have taken over the traditional DNA extraction techniques. However, to meet the demands of cost-effectiveness, ready availability, safety, reliability and purity in resource-limited settings, an improved traditional DNA extraction method which meet the above criteria is required. Aim: We therefore evaluated the modified salting out and double salt precipitation method, against QIAamp Blood Mini Kit. Materials and Methods: In a cross-sectional study, DNA was extracted from venous blood of 60 suspected typhoid fever patients who visited the Komfo Anokye Teaching Hospital diagnostics department to do laboratory investigations that required blood collection. Their DNA was extracted using the three different methods. Spectrophotometric measurement of the yields (ng/mu l) and purities (260/280 nm) of the extracted DNA was done. PCR analysis was performed on the DNA extracts to evaluate suitability for downstream analysis. We employed the Mann-Whitney, Kruskal-Wallis and Bland-Altman plots for statistical comparisons. Results: The modified double salt precipitation and enzymatic salt precipitation methods produced a higher yield than the QIAamp Blood Mini Kit method (P<0.01 each). The yield from the double salt precipitation method was higher than that of the enzymatic salt precipitation method (P=0.04). The level of purity of DNA extracted from all three methods were comparable (P=0.24). Conclusion: Our modified double salt and enzymatic salt precipitation techniques offer higher DNA yields than the commercially available QIAamp Blood Mini Kit and with comparable purity. We recommend the use of these modified techniques in resource-limited settings.