A Rapid and Simple Loop-Mediated Isothermal Amplification Assay for the Detection of Pseudomonas aeruginosa From Equine Genital Swabs

Current and Future Advances in the Detection and Surveillance of Biosecurity-Relevant Equine Bacterial Diseases Using Loop-Mediated Isothermal Amplification (LAMP)

Horses play an important role throughout the world, whether for work, culture, or leisure, providing an ever-growing significant contribution to the economy. The increase in importation and movement of horses, both nationally and internationally, has inevitably allowed for the global equine industry to grow. Subsequently, however, the potential for transmission of fatal equine bacterial diseases has also escalated, and devasting outbreaks continue to occur. To prevent such events, disease surveillance and diagnosis must be heightened throughout the industry. Current common, or "gold-standard" techniques, have shown to be inadequate at times, thus requiring newer technology to impede outbreaks. Loop-mediated isothermal amplification (LAMP) has proven to be a reliable, rapid, and accessible tool in both diagnostics and surveillance. This review will discuss equine bacterial diseases of biosecurity relevance and their current diagnostic approaches, as well as their respective LAMP assay developments. Additionally, we will provide insight regarding newer technology and advancements associated with this technique and their potential use for the outlined diseases.

A new aptamer/polyadenylated DNA interdigitated gold electrode piezoelectric sensor for rapid detection of Pseudomonas aeruginosa

Rapid detection of Pseudomonas aeruginosa (P. aeruginosa) is of great importance for accurate diagnosis and treatment of infected patients. In this study, a novel method was developed for the selective detection of P. aeruginosa by combing the sandwich type complex of magnetic bead/aptamer/polyadenylated-DNA with the sensitive detection platform of gold (Au) interdigital electrode connected to a multichannel series piezoelectric quartz crystal (Au IDE-MSPQC) system. Here, the magnetic bead (MB) was used as carrier for immobilization of the aptamer of P. aeruginosa. Polyadenylated DNA was bound to the aptamer through complementary strand pairing. When the P. aeruginosa was present in the sample solution, the polyadenylated DNA was replaced by the P. aeruginosa because of the specific interaction between P. aeruginosa and its aptamer. The released polyadenylated DNA strand in the detected solution could adsorb onto the surface of Au IDE by virtue of the strong interaction between adenine (A) and Au IDE, and result in sensitive frequency shift response of the MSPQC sensor. The limits of detection (LOD) of the method were as low as 9 CFU/mL in buffer and 52 CFU/mL in simulated blood sample. The proposed method was successfully applied to the selective detection of P. aeruginosa in blood samples. The constructed sensor is expected to find application for the rapid detection of P. aeruginosa in environment, food and clinical diagnosis.

Development of uracil-DNA-glycosylase-supplemented loop-mediated isothermal amplification coupled with nanogold probe (UDG-LAMP-AuNP) for specific detection of Pseudomonas aeruginosa

Pseudomonas aeruginosa (P. aeruginosa) is an important opportunistic pathogen that causes serious infections in humans, including keratitis in contact lens wearers. Therefore, establishing a rapid, specific and sensitive method for the identification of P. aeruginosa is imperative. In the present study, the uracil-DNA-glycosylase-supplemented loop-mediated isothermal amplification combined with nanogold labeled hybridization probe (UDG-LAMP-AuNP) was developed for the detection of P. aeruginosa. UDG-LAMP was performed to prevent carry over contamination and the LAMP reactions can be readily observed using the nanogold probe. A set of 4 primers and a hybridization probe were designed based on the ecfX gene. The UDG-LAMP reactions were performed at 65°C for 60 min using the ratio of 40% deoxyuridine triphosphate to 60% deoxythymidine triphosphate. The detection of UDG-LAMP products using the nanogold labeled hybridization probe, which appeared as a red-purple color, was examined at 65°C for 5 min with 40 mM MgSO₄. The UDG-LAMP-AuNP demonstrated specificity to all tested isolates of P. aeruginosa without cross reaction to other bacteria. The sensitivity for the detection of pure culture was 1.6×10³ colony-forming units (CFU) ml⁻¹ or equivalent to 3 CFU per reaction while that of polymerase chain reaction was 30 CFU per reaction. The detection limit of spiked contact lenses was 1.1×10³ CFU ml⁻¹ or equivalent to 2 CFU per reaction. In conclusion, the UDG-LAMP-AuNP assay was rapid, simple, specific and was effective for the identification of P. aeruginosa in contaminated samples.