Detection of Aeromonas hydrophila possessing aerolysin gene using gold nanoparticle probe.

OBJECTIVE: The aerolysin (aerA) is a virulence indicator used to identify the pathogenicity of the Aeromonas strain. Targeting a pathogen's crucial virulence gene for detection is essential, as it determines the potential threat to the host. This study aimed to develop a gold nanoparticle (AuNP) probe for detecting the gene aer A in Aeromonas hydrophila among field samples.

MATERIALS AND METHODS: Kidney samples among both healthy and sick Nile tilapias in five provinces of Luzon Island were collected for bacterial analysis. Screening using specific primers targeting aer A was conducted in parallel with testing the AuNPs probe on the same sample set. The positive control provided by BFAR-NFLD, confirmed by polymerase chain reaction (PCR) assay, was used as a positive sample containing the target gene.

RESULTS: The AuNP probe demonstrated a computed accuracy of 81.32%, sensitivity of 100%, and specificity of 81.26%. Among the 257 reactions, 59 were false positives, while no false negative results were observed. The AuNP probe could detect aer A at levels as low as 30 ng/µl. The low prevalence of the target gene may be attributed to the use of general media instead of specific media like Rimler-Shotts agar.

CONCLUSION: The established colorimetric detection method for A. hydrophila with the aer A gene offers a swift alternative to PCR, negating the requirement for advanced equipment like a thermal cycler.