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Background: Salmonella enterica subsp. enterica serovar Kentucky (antigenic formula 8,20:i:z6) is a serovar of the O:8 (C2-C3) serogroup. This serovar is commonly found in animals in the U.S. (Chickens, turkeys and cows), but rarely is reported in human cases. It is the most common serovar identified in non-clinical non-human sources, according to CDC, 2011. However, in Europe, serovar Kentucky is found in approx. 1% of the human cases. 

A number of human cases have been reported in Europe in travelers from Asia and Africa. However, there are limited outbreaks with epidemiological investigation and clear source identification have been reported.


In the U.S., it is commonly found in animals (specifically cattle and poultry) and in meat. In Europe, Asia and Africa, this serovar is also regularly isolated from humans with symptoms consistent with salmonellosis.

NCBI PD link for serovar Kentucky: https://www.ncbi.nlm.nih.gov/pathogens/isolates/#(taxgroup_name:%22Salmonella%20enterica%22)%20AND%20computed_types:(%22serotype=Kentucky%22)

Genetic characteristics: Serovar Kentucky str. CVM29188 is a multidrug resistant strain that contains three plasmids of 46, 101, and 146 kb. The two large plasmids are conjugative plasmids that carry antimicrobial resistance genes. The largest plasmid of 146 kb shows the same backbone and virulence genes as virulence plasmids of Avian Pathogenic E. coli (APEC). The SGI1-K strain, isolated from Indian spices, is another multidrug resistant strain that contains the resistance genes inserted in the chromosome in a genomic island (Salmonella Genomic Island 1 variant SGI1-K). In Europe and Canada, multidrug resistant serovar Kentucky strains have been found. A highly resistant clone of S. Kentucky (MLST type ST198), has been reported to be isolated in Canada and in Europe in travelers returning from Asia and Africa. This strain shows resistance to β-lactam antibiotics, carbapenems, quinolones, aminoglycosides, co-trimoxazole (trimethoprim-sulfamethoxazole), and to azithromycin. Molecular characterization shows a chromosomal genomic island carrying the resistance genes that confer resistance to these antimicrobials.

Phylogenetic and pan-genomic analyses that included completely sequenced S. Kentucky and other Salmonella serovars concluded that S. Kentucky (i) belongs to clade A, according to den Bakker et al. (2011) classification, (ii) appears to have several evolutionary origin, and (iii) contains 127 gene families unique to this serovar. Chen et al. found that serovar Kentucky is a polyphyletic serovar with two lineages identified (Kentucky A and Kentucky B). While Kentucky A is associated with chicken (the majority of isolates are from the US), Kentucky B (the majority of isolates are from the UK) is associated with cattle. There are two clonal subclades identified in the Kentucky B Clade 2. Kentucky ST 152 was found to be predominant in US chickens and appears to show attenuated human virulence. 

Animal reservoir: Chicken is the main reservoir for serovar Kentucky. However, one clade has been found to be associated with cattle. 

Geographical distribution: Serovar Kentucky is widely distributed and can be found globally. 

Human outbreaks: Human outbreaks associated with serovar Kentucky are rare. Here we described one outbreak we found. 

Year

Location

Associated source

Number of cases

2016US: multistateAlfalfa sprouts11

1 25 other cases associated with this outbreak (n=26) were infected by Salmonella Muenchen.

Animal outbreaks:

Year

Location

Breed

Number of cases

2016AustraliaArctocephalus forsteri17

1 Three of the 7 long-nosed fur seals showed clinical disease and died within 3 days. 

Border rejections:

Year

Exporting country

Importing country

Associated source

Product category

2023IndiaGermanySesame seeds1Nuts, nut products and seeds
2023UkrainePolandChicken meatPoultry meat and poultry meat products
2020GambiaUnited KingdomFish maws for isinglass2Fish and fish products

1 Salmonella Kentucky and Salmonella Senftenberg were both found.

2 Salmonella Kentucky and Salmonella Senftenberg were both found.

Recalls:

YearLocationRecalled foodType
2021FinlandFresh mint from Kenyaherbs and spices

Relevant links:

  1. https://pmc.ncbi.nlm.nih.gov/articles/PMC2747853/
  2. https://pmc.ncbi.nlm.nih.gov/articles/PMC1797678/
  3. https://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-12-425
  4. https://pmc.ncbi.nlm.nih.gov/articles/PMC3175032/
  5. https://www.microbiologyresearch.org/content/journal/mgen/10.1099/mgen.0.001089#tab2
  6. https://journals.asm.org/doi/10.1128/mmbr.00015-13
  7. https://journals.asm.org/doi/10.1128/mbio.01913-24?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed
  8. https://pubmed.ncbi.nlm.nih.gov/21813512/
  9. https://archive.cdc.gov/#/details?url=https://www.cdc.gov/salmonella/muenchen-02-16/index.html
  10. https://pubmed.ncbi.nlm.nih.gov/33269723/
  11. https://webgate.ec.europa.eu/rasff-window/screen/notification/591197
  12. https://webgate.ec.europa.eu/rasff-window/screen/notification/607336
  13. https://webgate.ec.europa.eu/rasff-window/screen/notification/416870
  14. https://webgate.ec.europa.eu/rasff-window/screen/notification/494162


  1. http://wwwnc.cdc.gov/eid/article/19/6/12-1351_article.htm
  2. http://www.thelancet.com/journals/laninf/article/PIIS1473-3099%2813%2970124-5/abstract
  3. http://aac.asm.org/content/56/10/5096.full
  4. http://www.ncbi.nlm.nih.gov/nuccore/AY463797
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