Prevalence of invA Gene of Salmonella spp. in Fish and Fishery Resources from Manila Bay Aquaculture Farms Using Real-Time PCR

Abstract

Manila Bay contributes significantly to the Philippines’ economy through industry, trade, tourism, and agriculture. However, microbiological contamination in the bay is putting it at risk in the present. Pathogen contamination of the water poses a serious threat to food safety, implicating public health. To address these concerns, the present study examined the prevalence of Salmonella in six different aquaculture commodities, Perna viridis (mussel), Crassostrea iridalei (oyster), Scylla serrata (crab), Penaeus spp. (shrimp), Oreochromis niloticus (tilapia), and Chanos chanos (milkfish), as well as in environmental water from growing areas. A tandem approach of culture-based and real-time PCR methods for the isolation and identification of Salmonella was carried out. To accurately identify the isolates, a real-time PCR Taqman assay based on the invA gene was used. Among the fishery resources examined, no positive samples were observed from C. chanos and O. niloticus. In addition, Salmonella was found in twenty (20) samples, representing 16.26% of all aquaculture commodities collected. Furthermore, Salmonella was found in 13.58% of the 81 environmental water samples examined. P. viridis had the highest prevalence of 55.55% out of 18 samples examined. Samples contaminated with Salmonella failed to meet the regulatory limits set by BFAR FAO 210 series 2001 and EC No. 2073/2005. In addition, it was observed that the sample matrix had a significant impact on the presence of Salmonella (p < 0.05). However, the spatial and temporal distribution of Salmonella did not vary greatly (p > 0.05). This study underscores the importance of imposing strict policies by regulatory bodies to prevent diseases, thus avoiding severe health implications.