S. Chester¶

At a Glance


Antigenic Formula	`1,4,[5],12:e,h:e,n,x`
Serogroup	O:4 (B)
NCBI Pathogen Detection	View isolates

Background Information¶

Salmonella enterica subsp. enterica serovar Chester (antigenic formula: 1,4,[5],12:e,h:e,n,x) is a serovar of the O:4 (B) serogroup. In 1937, this serovar was first isolated from humans during a food poisoning outbreak in the hospital of Chester, United Kingdom. Serovar Chester is a rare serovar worldwide. For example, in Canada, it only accounted for an average of seven human infections per year. In the US during 2001-2011, only 403 human cases have been reported. In addition, animal and food surveillance have not found serovar Chester in these sources in the US.

Genetic Characteristics¶

Serovar Chester has been found to be polyphyleticwith two lineages identified. Multidrug resistancewas identified in two isolates of serovar Chester (ST2063), which harbored resistance determinants across five distinct classes of antibiotics. Whole genome sequencing of serovar Chester in Norway revealedfour geographically distinct clusters. All isolates within the African cluster exhibited resistance to at least one class of antimicrobials, whereas resistance was uncommon in the other clusters.

Animal Reservoir¶

There is not clear evidence of the animal reservoir for this serovar, although serovar Chester has been found in various animals, including turkeys, cattle, reptiles, and birds.

Geographical Distribution¶

Serovar Chester have been reportedworldwide, including countries in North (US, Canada) and South America (Brazil), Morocco and Australia.

Human/Animal Outbreaks¶

Despite the fact that this is a rare serovar, multiple outbreaks have been reported. Below are examples.

Year	Location	Associated source	Number of cases
2010	Canada	Headcheese	33
2010	US: multistate	Frozen meals	44
2005	Australia	Tap water	26
1998	Australia	Turtle meat	36

Border Rejections¶

Year	Exporting country	Importing country	Associated source	Product category
2023	Spain	France	Frozen chicken drumstick¹	Poultry meat and poultry meat products
2023	Turkey	Switzerland	Red Paprika, sweet	Herbs and spices
2021	The United Kingdom	Denmark	Fishmeal pellets for farmed salmon	Feed materials

¹ Salmonella Vichow and Salmonella Chester were both found.

Recalls¶

Year	Location	Recalled food	Type
2024	Germany	Organic moringa powder from Sri Lanka	Dietetic foods, food supplements and fortified foods