WGS of contamination cases should become standard practice for commercial laboratories where their findings of a positive sample will result in large value recalls. Laboratories should have their positive control strains tested as other positive samples recently found. Additionally, commercial laboratories should already have an aggressive environmental monitoring program.
International Journal of Food Microbiology
International Journal of Food Microbiology
Volume 298, 2 June 2019, Pages 39-43
https://www.sciencedirect.com/science/article/pii/S0168160518307785
Whole genome sequencing used in an industrial context reveals a Salmonella laboratory cross-contaminationKatiaRouzeau-Szynalskia, Caroline Barrettoa, Coralie Fournierb, Deborah Moineb, Johan Gimoneta, Leen Baerta
https://doi.org/10.1016/j.ijfoodmicro.2019.03.007
https://www.sciencedirect.com/science/article/pii/S0168160518307785
Whole genome sequencing used in an industrial context reveals a Salmonella laboratory cross-contaminationKatiaRouzeau-Szynalskia, Caroline Barrettoa, Coralie Fournierb, Deborah Moineb, Johan Gimoneta, Leen Baerta
https://doi.org/10.1016/j.ijfoodmicro.2019.03.007
Abstract
In 2013, during a routine laboratory analysis performed on food samples, one finished product from a European factory was tested positive for Salmonella Hadar. At the same period, one environmental isolate in the same laboratory was serotyped Salmonella Hadar. Prior to this event, the laboratory performed a proficiency testing involving a sample spiked with NCTC 9877 Salmonella Hadar. The concomitance of Salmonella Hadar detection led to the suspicion of a laboratory cross-contamination between the Salmonella Hadar isolate used in the laboratory proficiency testing and the Salmonella Hadar isolate found on the finished product by the same laboratory. Since the classical phenotypic serotyping method is able to attribute a serotype to Salmonella isolates with a common antigenic formula, but cannot differentiate strains of the same serotype within the subspecies, whole genome sequencing was used to test the laboratory cross-contamination hypothesis. Additionally, 12 Salmonella Hadar from public databases, available until the time of the event, were included in the whole genome sequencing analysis to better understand the genomic diversity of this serotype in Europe. The outcome of the analysis showed a maximum of ten single nucleotide polymorphisms (SNPs) between the isolates coming from the laboratory and the finished product, and thus confirmed the laboratory cross-contamination. These results combined with all additional investigations done at the factory, allowed to release finished product batches produced and thus circumvented unnecessary food waste and economic losses for the factory.
In 2013, during a routine laboratory analysis performed on food samples, one finished product from a European factory was tested positive for Salmonella Hadar. At the same period, one environmental isolate in the same laboratory was serotyped Salmonella Hadar. Prior to this event, the laboratory performed a proficiency testing involving a sample spiked with NCTC 9877 Salmonella Hadar. The concomitance of Salmonella Hadar detection led to the suspicion of a laboratory cross-contamination between the Salmonella Hadar isolate used in the laboratory proficiency testing and the Salmonella Hadar isolate found on the finished product by the same laboratory. Since the classical phenotypic serotyping method is able to attribute a serotype to Salmonella isolates with a common antigenic formula, but cannot differentiate strains of the same serotype within the subspecies, whole genome sequencing was used to test the laboratory cross-contamination hypothesis. Additionally, 12 Salmonella Hadar from public databases, available until the time of the event, were included in the whole genome sequencing analysis to better understand the genomic diversity of this serotype in Europe. The outcome of the analysis showed a maximum of ten single nucleotide polymorphisms (SNPs) between the isolates coming from the laboratory and the finished product, and thus confirmed the laboratory cross-contamination. These results combined with all additional investigations done at the factory, allowed to release finished product batches produced and thus circumvented unnecessary food waste and economic losses for the factory.
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