Abstract
Salmonella spp. is a high-risk bacterial pathogen that is monitored in imported animal-derived feedstuffs. Serratia fonticola is the bacterial species most frequently confused with Salmonella spp. in traditional identification methods based on biochemical characteristics, which are time-consuming and labor-intensive, and thus unsuitable for daily inspection and quarantine work. In this study, we established a duplex real-time qPCR method with invA- and gyrB-specific primers and probes corresponding to Salmonella spp. and S. fonticola. The method could simultaneously detect both pathogens in imported feedstuffs, with a minimum limit of detection for Salmonella spp. and S. fonticola of 197 copies/μL and 145 copies/μL, respectively (correlation coefficient R2 = 0.999 in both cases). The amplification efficiency for Salmonella spp. and S. fonticola was 98.346% and 96.49%, respectively. Detection of fishmeal was consistent with method GB/T 13091-2018, and all seven artificially contaminated imported feed samples were positively identified. Thus, the developed duplex real-time qPCR assay displays high specificity and sensitivity, and can be used for the rapid and accurate detection of genomic DNA from Salmonella spp. and S. fonticola within hours. This represents a significant improvement in the efficiency of detection of both pathogens in imported feedstuffs.
Highlights
Salmonella spp. are ubiquitous Gram-negative bacteria in the environment and include six different subspecies and more than 2000 serotypes that infect a wide range of hosts, often causing severe food poisoning outbreaks in humans and other animals
S. fonticola is a species belonging to the Serratia genus that was first isolated from water and soil in 1979 (Gavini et al 1979)
Two Salmonella spp. colonies were cultured at 36 ± 1 °C for 48 h in CHROMagar, one on the medium slope, the other punctured through the agar, and both were inoculated on trisaccharide iron medium
Summary
Salmonella spp. are ubiquitous Gram-negative bacteria in the environment and include six different subspecies and more than 2000 serotypes that infect a wide range of hosts, often causing severe food poisoning outbreaks in humans and other animals. Subsequent studies showed that S. fonticola, At present, the detection of Salmonella spp. in imported animal-derived feeds (fish meal and chicken powder) involves non-selective enrichment, selective enrichment, selective platelet culturing, biochemical culturing of suspected Salmonella colonies (triglyceride tests, etc.), and even serological typing. These conventional methods require at least 3 days to detect. Suspected Salmonella colonies based on selective plate isolation and culturing of imported animal-derived feeds often turn out to be S. fonticola when biochemical properties are investigated (Chen et al 2016). A novel method involving polymer fluorescent nanoparticles as biosensor probes has been described for the detection of Salmonella (Jain et al 2016), which takes only 3 h, but cannot be applied to large volume detection due to its prohibitively high cost
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
