Salmonella Thompson outbreak associated with consumption of chicken shawarma and the usefulness of genome sequencing in the investigation

Abstract

Background: A sudden increase in Salmonella Thompson (S. Thompson) cases distributed throughout three border regions in the province of Quebec in November 2016 triggered a provincial investigation to identify a common source of contamination and to put the appropriate control measures into place.

Prevalence and Antimicrobial Resistance of Salmonella Isolated From Dead-in-Shell Chicken Embryos in Shandong, China

“…Serotyping is an effective approach to evaluating modes of transmission to develop strategies for preventing disease spread within poultry facilities (30). We found that S. Thompson, which is a member of Salmonella serogroup C1 commonly associated with disease in humans (31) and isolated in poultry and poultry eggs (8,28,32), was the most prevalent isolate in the present study. This is in contrast to studies in Shanghai and Sichuan that had identified S. Enteritidis as the most common serovar in commercial chicken farms (25,33), while S. Indiana was found to be dominant in Shandong (34), and S. Weltevreden was dominant in Central Vietnam (35).…”

“…We found that S . Thompson, which is a member of Salmonella serogroup C1 commonly associated with disease in humans ( 31 ) and isolated in poultry and poultry eggs ( 8 , 28 , 32 ), was the most prevalent isolate in the present study. This is in contrast to studies in Shanghai and Sichuan that had identified S .…”

“…An MLST approach led to the classification of these 86 Salmonella isolates into four STs, all of which have been previously linked to the incidence of human salmonellosis ( 31 , 39 ). ST26 was the most prevalent ST in the present study, in contrast to the results of a prior study of breeder chicken flocks in nine Chinese provinces, which found ST92 to be the most prevalent in sample sites ( 18 ).…”

Spatial and space-time clustering and demographic characteristics of human nontyphoidal Salmonella infections with major serotypes in Toronto, Canada

“…Interestingly, researchers from the neighbouring province of Quebec, Canada, reported an S . Thompson outbreak [ 49 ] at the same time period (November to December 2016) as the Toronto space-time cluster. The Quebec outbreak was linked to the consumption of chicken shawarma at a local restaurant chain in the city of Montreal and its neighboring regions.…”

“…We identified a high S. Thompson infection rate space-time cluster in the north-east region of Toronto between September 2016 and December 2016 ( Table 1, Fig 6), and 63% of cases that were included in this cluster were linked to an outbreak by public health enteric outbreak investigators. Interestingly, researchers from the neighbouring province of Quebec, Canada, reported an S. Thompson outbreak [49] at the same time period (November to December 2016) as the Toronto space-time cluster. The Quebec outbreak was linked to the consumption of chicken shawarma at a local restaurant chain in the city of Montreal and its neighboring regions.…”