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

This study evaluates the performance of the Direct-to-PCR (D2P) method as a streamlined, extraction-independent 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.