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Salmonella

Updated : February 2, 2024





Background

Salmonella bacteria is a Gram-negative, hydrogen sulfide-generating, an acid-labile intracellular microbe that causes gastroenteritis and cross-infection between humans and animals worldwide. Many animals have been identified as Salmonella carriers.

Chickens are animal carriers of Salmonella enteritidis, which can cause inflammatory diarrhea if consumed raw. Salmonella can potentially cause substantially localized infection in immunocompromised persons. There are about 2,500 Salmonella serotypes in the world.

Epidemiology

The most prevalent form of Salmonella infection in developed countries, such as the United States, is enterocolitis and gastroenteritis. In the United States, around 1 million cases of non-typhoidal salmonella are reported each year. Enteric fever is rare in the United States and is usually brought in from another country.

However, it is a worldwide concern, with over 20 million new infections and over 200,000 fatalities each year. Typhoid fever is common in Sub-Saharan Africa and South Asia, with rates exceeding 100 per 100,000 persons each year.

Because of poor sanitation and contaminated food and water supplies from infected feces, the incidence and infection risk in these places are considerable, particularly in low to middle-income nations.

Anatomy

Pathophysiology

The non-typhoidal Salmonella usually causes gastroenteritis, but S. typhi causes systemic disease by using virulence factors. The Vi antigen, a polysaccharide capsule that inhibits phagocytosis, is one form of virulence factor generated by S. typhi but not non-typhoidal Salmonella. Typhoid toxin is another virulence component exclusive to typhoidal Salmonella.

Typhoid toxin is produced when the Salmonella bacterium is intracellular and discharged to the extracellular environment via vesicles, resulting in lethargy, decreased circulating neutrophils, and other neurological problems.

Other important virulence elements include the flagella, which assists in movement, and the type 3 secretion system, which permits insertion and adhesion into human nonphagocytic cells.

Etiology

Salmonella is a gram-negative bacterium in the Enterobacteriaceae family. Multiple serovars are present in each subspecies of Salmonella. S. subspecies of enterica. The serotypes that are most important to human pathology are found in enterica, which also has the most serotype.

The Salmonella serotypes typhimurium, enteritidis, newport, and javiana are a few of the most prevalent serotypes. Typhoid and paratyphoid fevers are brought on by serotype typhi and paratyphi, which results in enteric fever. Salmonella typhoidal is only seen in humans.

Nontyphoidal Salmonella is produced by other Salmonella enterica serotypes and can infect a variety of vertebrate animals, including humans. Some serotypes are only found in nonhuman vertebrate species.

Genetics

Prognostic Factors

With non-typhoidal salmonella infection, the majority of patients recover without any long-term effects. However, malnourished patients and individuals receiving inadequate supportive treatment may experience persistent diarrhea, dehydration, and fever. Patients with immunocompromised states and those who need antibiotic therapy may experience a prolonged disease course with higher disease severity and frequently have systemic involvement.

Patients with enteric fever typically make a full recovery if they receive prompt diagnosis and treatment. Negative results are more likely to happen if the diagnosis is delayed and the proper antibiotics and doses are not utilized. Patients with malnutrition who are infected with multidrug-resistant strains may experience additional problems.

Patients who do not respond to the antibiotic medication and continue to excrete the bacteria for more than three months are considered chronic carriers. Children are rarely chronic carriers; however, the prevalence rises with age and among individuals who have gallbladder disease. Patients who also have schistosomiasis may develop chronic urinary carriers.

Clinical History

Physical Examination

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Medication

Media Gallary

References

https://www.ncbi.nlm.nih.gov/books/NBK555892/

Salmonella

Updated : February 2, 2024




Salmonella bacteria is a Gram-negative, hydrogen sulfide-generating, an acid-labile intracellular microbe that causes gastroenteritis and cross-infection between humans and animals worldwide. Many animals have been identified as Salmonella carriers.

Chickens are animal carriers of Salmonella enteritidis, which can cause inflammatory diarrhea if consumed raw. Salmonella can potentially cause substantially localized infection in immunocompromised persons. There are about 2,500 Salmonella serotypes in the world.

The most prevalent form of Salmonella infection in developed countries, such as the United States, is enterocolitis and gastroenteritis. In the United States, around 1 million cases of non-typhoidal salmonella are reported each year. Enteric fever is rare in the United States and is usually brought in from another country.

However, it is a worldwide concern, with over 20 million new infections and over 200,000 fatalities each year. Typhoid fever is common in Sub-Saharan Africa and South Asia, with rates exceeding 100 per 100,000 persons each year.

Because of poor sanitation and contaminated food and water supplies from infected feces, the incidence and infection risk in these places are considerable, particularly in low to middle-income nations.

The non-typhoidal Salmonella usually causes gastroenteritis, but S. typhi causes systemic disease by using virulence factors. The Vi antigen, a polysaccharide capsule that inhibits phagocytosis, is one form of virulence factor generated by S. typhi but not non-typhoidal Salmonella. Typhoid toxin is another virulence component exclusive to typhoidal Salmonella.

Typhoid toxin is produced when the Salmonella bacterium is intracellular and discharged to the extracellular environment via vesicles, resulting in lethargy, decreased circulating neutrophils, and other neurological problems.

Other important virulence elements include the flagella, which assists in movement, and the type 3 secretion system, which permits insertion and adhesion into human nonphagocytic cells.

Salmonella is a gram-negative bacterium in the Enterobacteriaceae family. Multiple serovars are present in each subspecies of Salmonella. S. subspecies of enterica. The serotypes that are most important to human pathology are found in enterica, which also has the most serotype.

The Salmonella serotypes typhimurium, enteritidis, newport, and javiana are a few of the most prevalent serotypes. Typhoid and paratyphoid fevers are brought on by serotype typhi and paratyphi, which results in enteric fever. Salmonella typhoidal is only seen in humans.

Nontyphoidal Salmonella is produced by other Salmonella enterica serotypes and can infect a variety of vertebrate animals, including humans. Some serotypes are only found in nonhuman vertebrate species.

With non-typhoidal salmonella infection, the majority of patients recover without any long-term effects. However, malnourished patients and individuals receiving inadequate supportive treatment may experience persistent diarrhea, dehydration, and fever. Patients with immunocompromised states and those who need antibiotic therapy may experience a prolonged disease course with higher disease severity and frequently have systemic involvement.

Patients with enteric fever typically make a full recovery if they receive prompt diagnosis and treatment. Negative results are more likely to happen if the diagnosis is delayed and the proper antibiotics and doses are not utilized. Patients with malnutrition who are infected with multidrug-resistant strains may experience additional problems.

Patients who do not respond to the antibiotic medication and continue to excrete the bacteria for more than three months are considered chronic carriers. Children are rarely chronic carriers; however, the prevalence rises with age and among individuals who have gallbladder disease. Patients who also have schistosomiasis may develop chronic urinary carriers.

https://www.ncbi.nlm.nih.gov/books/NBK555892/