Biology:Salmonella enterica

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Short description: Species of bacterium

Salmonella enterica
"S. enterica" Typhimurium colonies on a Hektoen enteric agar plate
S. enterica Typhimurium colonies on a Hektoen enteric agar plate
Scientific classification edit
Domain: Bacteria
Phylum: Pseudomonadota
Class: Gammaproteobacteria
Order: Enterobacterales
Family: Enterobacteriaceae
Genus: Salmonella
Species:
S. enterica
Binomial name
Salmonella enterica
(ex Kauffmann & Edwards 1952) Le Minor & Popoff 1987
Subspecies
  • S. enterica subsp. arizonae
  • S. enterica subsp. diarizonae
  • S. enterica subsp. enterica
  • S. enterica subsp. houtenae
  • S. enterica subsp. indica
  • S. enterica subsp. salamae

Salmonella enterica (formerly Salmonella choleraesuis) is a rod-shaped, flagellate, facultative anaerobic, Gram-negative bacterium and a species of the genus Salmonella.[1] It is divided into six subspecies, arizonae (IIIa), diarizonae (IIIb), houtenae (IV), salamae (II), indica (VI), and enterica (I).[2] A number of its serovars are serious human pathogens; many of them are (more specifically) serovars of Salmonella enterica subsp. enterica.

Pathogenesis

Secreted proteins are of major importance for the pathogenesis of infectious diseases caused by S. enterica. A remarkably large number of fimbrial and nonfimbrial adhesins are present in Salmonella, and mediate biofilm formation and contact to host cells. Secreted proteins are also involved in host-cell invasion and intracellular proliferation, two hallmarks of Salmonella pathogenesis.[3]

DNA repair capability

Exposure of S. enterica to bile salts, such as sodium deoxycholate, induces the SOS DNA damage response indicating that in this organism bile salts cause DNA damage.[4] Bile salt exposure is found to increase GC to AT transition mutations and also to induce genes of the OxyR and SoxRS regulons suggesting further that bile salts specifically cause oxidative DNA damage.[4] Mutants of S. enterica that are defective in enzymes required for the process of base excision repair are sensitive to bile salts. This indicates that wild-type S. enterica uses base excision repair to remove DNA damages caused by the bile salts.[4] The RecBCD enzyme which functions in recombinational repair of DNA is also required for bile salt resistance.[citation needed]

Small noncoding RNA

Small nonprotein-coding RNAs (sRNA) are able to perform specific functions without being translated into proteins; 97 bacterial sRNAs from Salmonella Typhi were discovered.[5]

AsdA (antisense RNA of dnaA) is a cis-encoded antisense RNA of dnaA described in S. enterica serovar Typhi. It was discovered by deep sequencing and its transcription was confirmed by Northern blot and RACE analysis. AsdA is estimated to be about 540 nucleotides long, and represents the complementary strand to that encoding DnaA, a protein that plays a central role in the initiation of DNA replication and hence cellular division. In rich media, it is highly expressed only after reaching the stationary growth phase, but under limiting iron or osmotic stress, it is already expressed during exponential growth. Overexpression of AsdA stabilizes dnaA mRNA, increasing its levels and thereby enhancing its rate of translation. This suggests that AsdA is a regulator of DNA replication.[6]

Nomenclature

S. enterica has six subspecies, and each subspecies has associated serovars that differ by antigenic specificity.[7] S. enterica has over 2500 serovars.[8] Salmonella bongori was previously considered a subspecies of S. enterica, but it is now the other species in the genus Salmonella. Most of the human pathogenic Salmonella serovars belong to the enterica subspecies. These serogroups include S. Typhi, S. Enteritidis, S. Paratyphi, S. Typhimurium, and S. Choleraesuis. The serovars can be designated as written in the previous sentence (capitalized and nonitalicized following the genus), or as follows: "S. enterica subsp. enterica, serovar Typhi".[9]

S. e. subsp. arizonae, named after the state of Arizona, is most commonly found in cold-blooded animals (especially snakes), but can also infect turkey, sheep, and humans. It is endemic in southwestern United States.[10] The similar S. e. subsp. diarizonae also infects snakes and occasionally humans.[11]

Epidemiology

Main page: Medicine:Salmonellosis

Most cases of salmonellosis are caused by food infected with S. enterica, which often infects cattle and poultry, though other animals such as domestic cats[12][13] and hamsters[14] have also been shown to be sources of infection in humans. It primarily resides in the intestinal tract of animals of humans and can be found in feedstuff, soil, bedding, litter, and fecal matter.[15]

The primary reservoir for the pathogen is poultry and 70% of human cases are attributed with the consumption of contaminated eggs, chicken, or turkey.[16] Raw chicken eggs and goose eggs can harbor S. enterica, initially in the egg whites, although most eggs are not infected. As the egg ages at room temperature, the yolk membrane begins to break down and S. enterica can spread into the yolk. Refrigeration and freezing do not kill all the bacteria, but substantially slow or halt their growth. Pasteurizing and food irradiation are used to kill Salmonella for commercially produced foodstuffs containing raw eggs such as ice cream. Foods prepared in the home from raw eggs, such as mayonnaise, cakes, and cookies, can spread salmonellae if not properly cooked before consumption. Salmonella is the leading foodborne pathogen in the United States, causing the most deaths and having the highest cost burden.[17] It is a resilient, microorganism capable of surviving long periods of time in hot and dry environments, increasing its effectiveness as a pathogen and making it able to survive the harsh environments of the gastrointestinal tract and farms. Salmonella has been found in 10 to 26% of farm environments in Tennessee, North Carolina, Alabama, California, and Washington.[18]

S. enterica genomes have been reconstructed from up 6,500 year old human remains across Western Eurasia, which provides evidence for geographic widespread infections with systemic S. enterica during prehistory, and a possible role of the Neolithization process in the evolution of host adaptation.[19] Additional reconstructed genomes from colonial Mexico suggest S. enterica as the cause of cocoliztli, an epidemic in 16th-century New Spain.[20]

Children under the age of 5 years, the elderly, and immunosuppressed adults are at an increased risk of systemic dissemination of the disease and need specialized treatment in order to combat the disease. Drinking extra fluids and antibacterial agents such as fluoroquinolones are typical treatment plans for Salmonella enterica.[21] Complications of the disease are characterized by an onset of fever with diarrhea and the mortality rate is 15% once these symptoms arise.[22]

See also

References

  1. ↑ Baron S, ed (1996). Salmonella. In: Baron's Medical Microbiology (4th ed.). Univ of Texas Medical Branch. (via NCBI Bookshelf). ISBN 978-0-9631172-1-2. 
  2. ↑ "Evolutionary Genomics of Salmonella enterica Subspecies". mBio 4 (2). March 2013. doi:10.1128/mBio.00579-12. PMID 23462113. 
  3. ↑ "Secreted Proteins and Virulence in Salmonella enterica". Bacterial Secreted Proteins: Secretory Mechanisms and Role in Pathogenesis. Caister Academic Press. 2009. ISBN 978-1-904455-42-4. 
  4. ↑ 4.0 4.1 4.2 "Repair of DNA damage induced by bile salts in Salmonella enterica". Genetics 174 (2): 575–84. October 2006. doi:10.1534/genetics.106.060889. PMID 16888329. 
  5. ↑ "Experimental identification and characterization of 97 novel npcRNA candidates in Salmonella enterica serovar Typhi". Nucleic Acids Research 38 (17): 5893–5908. September 2010. doi:10.1093/nar/gkq281. PMID 20460466. 
  6. ↑ "Identification and characterization of a cis-encoded antisense RNA associated with the replication process of Salmonella enterica serovar Typhi". PLOS ONE 8 (4): e61308. 2013-01-01. doi:10.1371/journal.pone.0061308. PMID 23637809. Bibcode: 2013PLoSO...861308D. 
  7. ↑ "Salmonella and Salmonellosis". Todar's Online Textbook of Bacteriology. http://www.textbookofbacteriology.net/salmonella.html. 
  8. ↑ Medical Microbiology (6th ed.). Philadelphia, PA: Mosby Elsevier. 2009. p. 307. ISBN 978-0-323-05470-6. 
  9. ↑ "A review of Salmonella enterica with particular focus on the pathogenicity and virulence factors, host specificity and antimicrobial resistance including multidrug resistance". Veterinary World 12 (4): 504–521. 2019. doi:10.14202/vetworld.2019.504-521. PMID 31190705. 
  10. ↑ "Salmonella enterica subspecies arizonae infection of adult patients in Southern Taiwan: a case series in a non-endemic area and literature review". BMC Infectious Diseases 16 (1): 746. December 2016. doi:10.1186/s12879-016-2083-0. PMID 27938338. 
  11. ↑ "Pet snakes as a reservoir for Salmonella enterica subsp. diarizonae (Serogroup IIIb): a prospective study". Applied and Environmental Microbiology 70 (1): 613–615. January 2004. doi:10.1128/AEM.70.1.613-615.2004. PMID 14711697. Bibcode: 2004ApEnM..70..613S. 
  12. ↑ "Salmonellosis in Animals – Digestive System" (in en). MSD Veterinary Manual. Rahway, NJ, USA: Merck & Co., Inc.. October 2022. https://www.msdvetmanual.com/digestive-system/salmonellosis/salmonellosis-in-animals. 
  13. ↑ "Highly suspected cases of salmonellosis in two cats fed with a commercial raw meat-based diet: health risks to animals and zoonotic implications". BMC Veterinary Research 13 (1): 224. July 2017. doi:10.1186/s12917-017-1143-z. PMID 28738871. 
  14. ↑ "Multidrug-resistant Salmonella enterica serotype Typhimurium associated with pet rodents". The New England Journal of Medicine 356 (1): 21–28. January 2007. doi:10.1056/NEJMoa060465. PMID 17202452. 
  15. ↑ "Salmonella enterica: survival, colonization, and virulence differences among serovars". TheScientificWorldJournal 2015: 520179. 2015-01-13. doi:10.1155/2015/520179. PMID 25664339. 
  16. ↑ "Surveillance for foodborne disease outbreaks – United States, 2016 : annual report". https://stacks.cdc.gov/view/cdc/59698. 
  17. ↑ "Ranking the disease burden of 14 pathogens in food sources in the United States using attribution data from outbreak investigations and expert elicitation". Journal of Food Protection 75 (7): 1278–1291. July 2012. doi:10.4315/0362-028X.JFP-11-418. PMID 22980012. 
  18. ↑ "Prevalence of Salmonella in diverse environmental farm samples". Journal of Food Protection 69 (11): 2576–2580. November 2006. doi:10.4315/0362-028X-69.11.2576. PMID 17133798. 
  19. ↑ "Emergence of human-adapted Salmonella enterica is linked to the Neolithization process". Nature Ecology & Evolution 4 (3): 324–333. March 2020. doi:10.1038/s41559-020-1106-9. PMID 32094538. 
  20. ↑ "Salmonella enterica genomes from victims of a major sixteenth-century epidemic in Mexico". Nature Ecology & Evolution 2 (3): 520–528. March 2018. doi:10.1038/s41559-017-0446-6. PMID 29335577. 
  21. ↑ "Salmonella Infection in Emergency Medicine Medication: Antibiotics, Antidiarrheals, Glucocorticoids". 8 March 2021. https://emedicine.medscape.com/article/785774-medication?form=fpf. 
  22. ↑ "Complications and mortality of non-typhoidal salmonella invasive disease: a global systematic review and meta-analysis". The Lancet. Infectious Diseases 22 (5): 692–705. May 2022. doi:10.1016/S1473-3099(21)00615-0. PMID 35114140. 

External links

Wikidata ☰ Q2264864 entry



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