The efficiencies of five commercially available nucleic acid extraction methods were evaluated for the recovery of a standardized inoculum of Legionella pneumophilain respiratory specimens (sputum and bronchoalveolar lavage [BAL] specimens). The concentrations of Legionella DNA recovered from sputa with the automated MagNA Pure (526,200 CFU/ml) and NucliSens (171,800 CFU/ml) extractors were greater than those recovered with the manual methods (i.e., Roche High Pure kit [133,900 CFU/ml], QIAamp DNA Mini kit [46,380 CFU/ml], and ViralXpress kit [13,635 CFU/ml]). The rank order was the same for extracts from BAL specimens, except that for this specimen type the QIAamp DNA Mini kit recovered more than the Roche High Pure kit.

We aimed to test the applicability of formalin-fixed and paraffin-embedded (FFPE) tissue samples for gene specific DNA methylation analysis after using two commercially available DNA isolation kits. Genomic DNA was isolated from 5 colorectal adenocarcinomas and 5 normal adjacent tissues from "recent", collected within 6 months, and "archived", collected more than 5 years ago, FFPE tissues using either High Pure FFPET DNA Isolation kit or QIAamp DNA FFPE Tissue kit. DNA methylation analysis of MAL, SFRP1 and SFRP2 genes, known to be hypermethylated in CRC, was performed using methylation-sensitive high resolution melting (MS-HRM) analysis and sequencing. QIAamp (Q) method resulted in slightly higher recovery in archived (HP: 1.22?±?3.18μg DNA; Q: 3.00?±?4.04μg DNA) and significantly (p?<?0.05) higher recovery in recent samples compared to High Pure method (HP) (HP: 4.10?±?2.91μg DNA; Q: 11.51?±?7.50μg DNA). Both OD260/280 and OD260/230 ratios were lower, but still high in the High Pure isolated archived and recent samples compared to those isolated with QIAamp. Identical DNA methylation patterns were detected for all 3 genes tested by MS-HRM with both isolation kits in the recent group. However, despite of higher DNA recovery in QIAamp slightly more reproducible methylation results were obtained from High Pure isolated archived samples. Sequencing confirmed DNA hypermethylation in CRCs. In conclusion, reproducible DNA methylation patterns were obtained from recent samples using both isolation kits. However, long term storage may affect the reliability of the results leading to moderate differences between the efficiency of isolation kits.