Salmonella enterica

Salmonella enterica (formerly Salmonella choleraesuis) is a rod-shaped, flagellate, facultative anaerobic, Gram-negativebacterium and a species of the genusSalmonella.^[1] It is divided into six subspecies, arizonae (IIIa), diarizonae (IIIb), houtenae (IV), salamae (II), indica (VI), and enterica (I).^[2][3] A number of its serovars are serious human pathogens; many of them are (more specifically) serovars of Salmonella enterica subsp. enterica.

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^[4][5] and hamsters^[6] have also been shown to be sources of infection in humans. It primarily resides in the intestinal tract of animals and humans and can be found in feedstuff, soil, bedding, litter, and fecal matter.^[7]

The primary reservoir for the pathogen is poultry and 70% of human cases are attributed to the consumption of contaminated eggs, chicken, or turkey.^[8] 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.^[9] 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.

S. enterica genomes have been reconstructed from up to 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.^[10] Additional reconstructed genomes from colonial Mexico suggest S. enterica as the cause of cocoliztli, an epidemic in 16th-century New Spain.^[11] In 1545, this outbreak of S. enterica spread explosively across what is now Mexico. Over the next century, the disease killed up to 90% of the Indigenous population.^[12]

Children under the age of five years, the elderly, and immunosuppressed adults are at an increased risk of systemic dissemination of the disease and need specialized treatment to combat the disease. Drinking extra fluids and antibiotics such as fluoroquinolones are typical treatments.^[13] Complications of the disease often appear as anemia or septicaemia, and the mortality rate is 15% once these symptoms arise.^[14]

The serogroup S. Typhi is the cause of typhoid fever.

S. enterica has six subspecies, and each subspecies has associated serovars that differ by antigenic specificity.^[15]S. enterica has over 2500 serovars.^[16]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 pathogenicSalmonella 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".^[17]

Subspecies S. e.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.^[18] The similar S. e. subsp. diarizonae also infects snakes and occasionally humans.^[19]

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.^[20] Regulatory proteins such as IgaA are also involved in maintaining envelope integrity and modulating stress responses during pathogenesis.

Die Exposition von S. enterica gegenüber Gallensalzen wie Natriumdesoxycholat induziert die SOS-DNA-Schadensantwort, was darauf hindeutet, dass Gallensalze in diesem Organismus DNA-Schäden verursachen . ^{[ 21 ]} Es wurde festgestellt, dass die Exposition gegenüber Gallensalzen die GC-zu-AT-Transitionsmutationen erhöht und außerdem Gene der OxyR- und SoxRS-Regulons induziert , was weiterhin nahelegt, dass Gallensalze spezifisch oxidative DNA-Schäden verursachen. ^{[ 21 ]} Mutanten von S. enterica , denen Enzyme fehlen, die für die Basenexzisionsreparatur benötigt werden, sind empfindlich gegenüber Gallensalzen. Dies deutet darauf hin, dass Wildtyp- S. enterica die Basenexzisionsreparatur nutzt, um durch Gallensalze verursachte DNA-Schäden zu beseitigen. ^{[ 21 ]} Das RecBCD- Enzym, das an der rekombinatorischen Reparatur von DNA beteiligt ist , ist ebenfalls für die Gallensalzresistenz erforderlich.

Kleine nicht-proteinkodierende RNAs ( sRNAs ) können spezifische Funktionen erfüllen, ohne in Proteine ​​übersetzt zu werden; 97 bakterielle sRNAs aus Salmonella Typhi wurden entdeckt. ^{[ 22 ]}

AsdA (Antisense-RNA von dnaA) ist eine cis- kodierte Antisense-RNA von dnaA , die in Salmonella enterica Serovar Typhi beschrieben wurde. Sie wurde mittels Hochdurchsatzsequenzierung entdeckt und ihre Transkription durch Northern-Blot- und RACE-Analyse bestätigt. AsdA ist schätzungsweise 540 Nukleotide lang und stellt den komplementären Strang zu dem für DnaA kodierenden Strang dar. DnaA ist ein Protein, das eine zentrale Rolle bei der Initiierung der DNA-Replikation und damit der Zellteilung spielt. In nährstoffreichen Medien wird AsdA erst nach Erreichen der stationären Wachstumsphase stark exprimiert, während es unter Eisenmangel oder osmotischem Stress bereits während des exponentiellen Wachstums exprimiert wird. Die Überexpression von AsdA stabilisiert die dnaA-mRNA, erhöht deren Konzentration und steigert dadurch die Translationsrate. Dies deutet darauf hin, dass AsdA ein Regulator der DNA-Replikation ist. ^{[ 23 ]}

• Bioterroranschlag der Rajneeshee im Jahr 1984
• AsrC kleine RNA
• Bakterielle kleine RNA
• HilD 3'UTR
• IsrM kleine RNA
• PinT kleine RNA
• Typhus Mary

• Anmerkungen zur Salmonella- Nomenklatur
• Salmonella+enterica in den Medical Subject Headings (MeSH) der US National Library of Medicine
• Aktuelle Forschung zu Salmonella typhimurium im Norwich Research Park
• " Salmonella enterica " . NCBI Taxonomy Browser . 28901.
• Typstamm von Salmonella enterica bei Bac Dive – der bakteriellen Diversitäts-Metadatenbank