Rapid and specific detection of Salmonella infections using chemically modified nucleic acid probes

• Published in: Analytica chimica acta Vol. 1054; pp. 157 - 166
• Main Authors: Machado, Isabel, Garrido, Victoria, Hernandez, Luiza I., Botero, Juliana, Bastida, Nora, San-Roman, Beatriz, Grilló, María-Jesús, Hernandez, Frank J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 25.04.2019; Elsevier BV
• Subjects: Bacteremia; Baseline studies; Biomarkers; Complications; Deoxyribonucleases - chemistry; Deoxyribonucleases - metabolism; Detection limits; Detection system; Diagnostic systems; Eggs; Food; Food chains; Food Microbiology - methods; Food production; Food Safety; Food sources; Foodborne diseases; Gastroenteritis; Incubation; Infections; Limit of Detection; Lymph nodes; Models, Molecular; Nuclease; Nucleases; Nucleic Acid Conformation; Nucleic acid probes; Nucleic acids; Oligonucleotide Probes - chemistry; Oligonucleotide Probes - genetics; Oligonucleotide Probes - metabolism; Oligonucleotides; Organic chemistry; Outbreaks; Probes; Protein Conformation; Public health; Safety regulations; Salmonella; Salmonella - enzymology; Salmonella - isolation & purification; Salmonella - metabolism; Salmonellosis; Serotypes; Substrates; Test procedures; Time Factors; Zoonoses; Salmonella; Nucleases; Nucleic acid probes; Detection system
• ISSN: 0003-2670; 1873-4324; 1873-4324
• DOI: 10.1016/j.aca.2018.12.027

Salmonella is a leading source of bacterial foodborne illness in humans, causing gastroenteritis outbreaks with bacteraemia occurrences that can lead to clinical complications and death. Eggs, poultry and pig products are considered as the main carriers of the pathogenic Salmonella for humans. To prevent this relevant zoonosis, key changes in food safety regulations were undertaken to improve controls in the food production chain. Despite these measures, large outbreaks of salmonellosis were reported worldwide in the last decade. Thus, new strategies for Salmonella detection are a priority for both, food safety and public health authorities. Such detection systems should provide significant reduction in diagnostic time (hours) compared to the currently available methods (days). Herein, we report on the discovery and characterization of nucleic acid probes for the sensitive and specific detection of live Salmonella within less than 8 h of incubation. We are the first to postulate the nuclease activity derived from Salmonella as biomarker of infection and its utility to develop innovative detection strategies. Our results have shown the screening and identification of two oligonucleotide sequences (substrates) as the most promising probes for detecting Salmonella – Sal-3 and Sal-5. The detection limits for both probes were determined with the reference Salmonella Typhimurium (STM 1) and Salmonella Enteritidis (SE 1) cultures. Sal-3 has reported LOD values around 105 CFU mL−1 for STM 1 and 104 CFU mL−1 for SE 1, while Sal-5 proves to be a slightly better probe, with LODs of 104 CFU mL−1 for STM 1 and 104 CFU mL−1 for SE 1. Both selected probes have shown the capability to recognize 49 out of 51 different Salmonella serotypes tested in vitro and the most frequent serotypes in porcine mesenteric lymph nodes as a standard sample used in fattening-pig salmonellosis baseline studies. Notably, our results showed 100% correlation between nuclease detection and the PCR-InvA or ISO-6579 standard method, underlining the great potential of this innovative nucleic acids technology to be implemented as a rapid method for food safety testing. [Display omitted] •Chemically modified nucleic acid probes for targeting bacteria in a specific manner.•Harnessing the biology of nucleases for detecting bacteria.•Innovative strategy with applications in food safety and clinical samples.