Evaluation of direct-to-PCR (D2P) method for molecular diagnosis of infectious diseases

Abstract: This study evaluates the performance of the Direct-to-PCR (D2P) method as a streamlined, extractionindependent alternative to conventional nucleic acid extraction techniques for diagnosing urinary tract infections, sexually transmitted infections, and respiratory tract infections. The D2P approach employs proprietary antimicrobial peptide-based lysis buffers tailored for bacterial, fungal, and viral targets, enabling direct amplification from clinical and contrived specimens without column- or bead-based purification. Comparative analyses were conducted against silica column-based (QIAGEN) and magnetic bead-based (KingFisher) extraction methods using both microbial reference isolates and 116 residual clinical samples. Results demonstrate that the D2P method yields comparable sensitivity and specificity to conventional extraction workflows across a diverse panel of pathogens—including Gram-negative and Gram-positive bacteria, Candida species, ssRNA viruses (e.g., CoV-229E, Parainfluenza Virus 1 and 2), and dsDNA viruses (e.g., HSV, HAdV). Notably, D2P outperformed both QIAGEN and KingFisher in extracting nucleic acids from Candida auris, a multidrug-resistant fungal pathogen. Limit of detection and amplification efficiency remained within acceptable ranges across all platforms, with R2 values between 0.92 and 0.99, and slopes consistent with MIQE standards. The D2P protocol reduced total sample processing time from ~120 min to ~45 min, minimized hands-on steps, and demonstrated effective performance in turbid or hemolyzed samples—making it suitable for high-throughput and resource-limited settings. However, limitations were observed in samples with high PCR-inhibitor content or low target yield, and broader validation across additional matrices is recommended. These findings support D2P as a reliable, efficient, and scalable molecular diagnostic alternative with broad clinical utility. Integration of D2P into diagnostic workflows could enhance access to rapid, cost-effective pathogen detection in both centralized laboratories and decentralized or point-of-care environments.