Salmonella enterica subsp. enterica
Salmonella enterica subsp. enterica | |
---|---|
Salmonella Typhimurium colonies on a Hektoen enteric agar plate | |
Scientific classification | |
Domain: | Bacteria |
Phylum: | Pseudomonadota |
Class: | Gammaproteobacteria |
Order: | Enterobacterales |
Family: | Enterobacteriaceae |
Genus: | Salmonella |
Species: | |
Subspecies: | S. e. subsp. enterica
|
Trinomial name | |
Salmonella enterica subsp. enterica |
Salmonella enterica subsp. enterica is a
Serovars
Salmonella enterica subsp. enterica serovars are defined based on their somatic (O) and flagellar (H) antigens, with over 2,600 serovars in total; only about 50 of these serovars are common causes of infections in humans.[2] Most of these serovars are found in the environment and survive in plants, water, and soil; many serovars have broad host ranges that allow them to colonize different species in mammals, birds, reptiles, amphibians, and insects. Zoonotic diseases, like Salmonella, spread between the environment and people.[3]
A number of techniques are currently used to differentiate between serotypes. These include looking for the presence or absence of antigens, phage typing, molecular fingerprinting and biotyping, where serovars are differentiated by which nutrients they are able to ferment. A possible factor in determining the host range of particular serovars is phage-mediated acquisition of a small number of genetic elements that enable infection of a particular host.[4] It is further postulated that serovars which infect a narrow range of species have diverged from ancestors with a broad host range, and have since specialised and lost the ability to infect some hosts.[5]
The CDC publishes a Salmonella Annual Report with a list of serovars most commonly associated with human illness, the top 10 serovars are listed below:[6]
Rank | Serotype | Percent |
---|---|---|
1 | Enteritidis | 16.8 |
2 | Newport | 10.1 |
3 | Typhimurium | 9.8 |
4 | Javiana | 5.8 |
5 | I 4,[5],12:i:- | 4.7 |
6 | Infantis | 2.7 |
7 | Muenchen | 2.6 |
8 | Montevideo | 2.2 |
9 | Braenderup | 2.1 |
10 | Thompson | 1.7 |
- | Other | 41.5 |
Studies have concluded most strains of Salmonella enterica subsp. enterica serovars possess serotype-specific virulence
In November 2016, a new strain of extensively drug resistant (XDR) Salmonella enterica serovar Typhi emerged in Pakistan, primarily from the cities of
Nomenclature
The nomenclature of Salmonella enterica has long been a topic of debate in the microbiology community.[15] Originally in the 1880s, Salmonella species were named after the disease, host, or geological location they were associated with; however, this taxonomic characterization was contested due to genus members being categorized incompatibly with their genetic similarities. In the 1980s, the emergence of nucleotide sequencing and DNA hybridization led many established bacteriologists such as Le Minor and Popoff (1987), Euzéby (1999), and Ezaki and Yabuuchi (2000) to put forth their proposals for nomenclature changes.[16] It was not until 2005, that Le Minor and Popoff reproposed and established that "Salmonella enterica" would be the approved species name – excluding Salmonella bongori – and that Salmonella enterica contains six subspecies, of which Salmonella enterica subsp. enterica contains the most serovars.[17] Technological advancements allow researchers to use whole genome sequencing data to identify and group serovars using two methods: sequence typing and antigen recognition.[18]
Serovar names are capitalized but not italicized or underlined. Serovars may be designated in full form or short form (includes just the genus and serovar names). For example, in full designation Salmonella enterica subsp. enterica serovar Typhi is written as such, but in short designation it is written as Salmonella Typhi.[19] Each serovar can have many strains, as well, which allows for a rapid increase in the total number of antigenically variable bacteria.[20]
Epidemiology
The World Health Organization characterizes
Survival and stress
There are factors that can increase the infection risk. These include a higher pH in the stomach, gastric resection, and treatment with anti acid buffering.
This strain is mesophilic and some can survive extremely low or high temperatures which can range from 2 °C – 54 °C.[29] Sigma factors inside the cell control the gene expression and they can sense the changes in the environment from the outer membrane by activation of genes that then respond to heat stress and adapt accordingly.[30] S. enterica also can quickly respond to cold temperatures by cold shock proteins (CSP) by synthesizing themselves so that the cell can later resume growth.[31] Chlorine can be a chemical stressor to S. enterica because once chlorine is present, S. enterica can produce a biofilm that provides itself with a exopolysaccharide matrix that has the ability of a chemical attack against chlorine.[32] From this, chlorine has preventative measures for biofilm formation in poultry drinking systems and this reduces the risk of S. enterica.[33] Successful adaptation allows S. enterica to withstand more acidic conditions, counteracting stomach antibacterial effects.[34]
References
- ^ Murray PR, Rosenthal KS, Pfaller MA (2009). Medical Microbiology (6th ed.). Philadelphia, PA: Mosby Elsevier. p. 307.
- ^ Grimont PA, Weill FX (November 2007). "Antigenic formulae of the Salmonella serovars". WHO Collaborating Centre for Reference and Research on Salmonella. 9: 1–66.
- PMID 26082128.
- PMID 11953356.
- PMID 25535353.
- ^ "National Enteric Disease Surveillance: Salmonella Annual Report, 2016" (PDF). CDC.gov. 2016.
- PMID 10943411.
- ^ CDC (2023-07-21). "Persistent Strain of Salmonella Infantis (REPJFX01) Linked to Chicken". Centers for Disease Control and Prevention. Retrieved 2023-11-19.
- ^ "FSIS NARMS Multi-Year Report – 2014-2019". fsis.usda.gov. 2023-02-10. Retrieved 2023-11-15.
- ^ "Isolates Browser - Pathogen Detection - NCBI". ncbi.nlm.nih.gov. Retrieved 2023-11-19.
- PMID 3182072.
- ^ Daley J (21 February 2018). "Typhoid Outbreak in Pakistan Linked to Extensively Drug-Resistant Bacteria". The Scientist Magazine®. Retrieved 2018-09-03.
- PMID 29463654.
- ^ "Extensively Drug-Resistant Typhoid Fever in Pakistan – Alert – Level 2, Practice Enhanced Precautions". Travel Health Notices. U.S. Centers for Disease Control and Prevention. Retrieved 2018-09-03.
- PMID 17760271.
- S2CID 19799923.
- PMID 10878026.
- PMID 33820940.
- ^ "Scientific Nomenclature". Emerging Infectious Dieases. Centers for Disease Control and Prevention. Retrieved 17 February 2020.
- ^ "Salmonella spp. comparative sequencing". Wellcome Trust Genome Campus. Archived from the original on 2007-11-14.
- ^ "Salmonella (non-typhoidal)". www.who.int. Retrieved 2023-10-26.
- PMID 21413334, retrieved 2023-10-26
- ^ a b Ehuwa O, Jaiswal AK, Jaiswal S. Salmonella, food safety and food handling practices. Foods. 2021;10(5). doi:https://www.mdpi.com/2304-8158/10/5/907/htm
- PMID 9571252.
- PMID 22587967.
- PMID 29487214.
- PMID 8406841.
- PMID 2404956.
- PMID 16339734.
- S2CID 84333218.
- PMID 9534239.
- PMID 9880479.
- PMID 10216758.
- PMID 16023758.