History and exam

Key diagnostic factors

common

presence of risk factors

Risk factors include food exposures, extremes of age (<12 months and >50 years), presence of an immunosuppressive state, low gastric acidity, exposure to symptomatic person, contact with animals (especially reptiles), use of antibiotics, poorly controlled diabetes mellitus, chronic granulomatous disease, iron overload, and malnutrition.

nausea/vomiting

Commonly occurs with Salmonella infections, but does not differentiate from other bacterial or viral aetiologies of gastroenteritis.

diarrhoea

Typically, stools are loose, moderate-volume, and without visible blood.

However, variations in presentation have been reported, including bloody stools and high- or low-volume stool quantities. Of note, in sub-Saharan Africa and in immunocompromised patients, invasive disease typically presents without diarrhoea.[28]​[77][78]​​

fever

Fevers as part of gastroenteritis are typically only 1 to 3 days in duration.

Other diagnostic factors

common

myalgias

Pain in a muscle or group of muscles may occur.

headache

May occur, especially in febrile patients.

abdominal tenderness

Diffuse, mild abdominal pain may accompany gastroenteritis.

Rarely, severe pain mimicking appendicitis has been reported.

signs of volume depletion

Dry mucous membranes, decreased skin turgor, and orthostatic vital signs suggest volume depletion due to vomiting and/or diarrhoea.

hyperactive bowel sounds

Increased bowel sounds may be present on examination.

uncommon

family history of Salmonella infection

A person infected with or carrying Salmonella (e.g., chronic carriers) may spread the infection to family members.

No genetic component is known for acquiring the infection.

Risk factors

strong

food exposures

Food exposures, including the ingestion of undercooked eggs or undercooked meats (especially poultry), are key risk factors. Raw produce that is contaminated by animal waste as well as peanut products have also been implicated.[41]

Most patients cannot identify a suspected food source.

extremes of age (<12 months and >50 years)

Infants and older people have a higher incidence of infections and are at risk for more severe disease.[42]

Outbreaks of salmonellosis among older people residing in long-term care facilities have been reported.[13]

presence of an immunosuppressive state

Patients who use immunosuppressive medications (e.g., corticosteroids); those with immunosuppressive conditions (e.g., HIV); transplant recipients; and those with rheumatological and connective tissue conditions or malignancy at increased risk.[43]

People living with AIDS are at very high risk for invasive non-typhoidal salmonellosis (up to 100-fold higher than the risk for immunocompetent patients).[44][45][46]​​ However, HIV is not a risk factor for enteric fever caused by Salmonella Typhi or S Paratyphi.[47]

Using anti-tumour necrosis factor-alpha therapies may predispose to severe disseminated disease, but not necessarily an increased incidence of Salmonella infections.[48]

low gastric acidity

Gastric acidity provides a protective barrier against infections. An acidic pH is required for the production of antimicrobial reactive nitrogen species in the stomach.[49] When this is reduced, clinical infections are more likely to occur and may be initiated by a lower inoculum of organisms. Patients who ingest antacids and those with conditions that lower gastric pH (extremes of age, pernicious anaemia) are at heightened risk.[36][39][40]

exposure to symptomatic person with Salmonella

People who have Salmonella gastroenteritis and are experiencing diarrhoea may spread the organism to others.

animal contact

Animals, especially reptiles and live poultry, may be carriers of Salmonella.

Handling animals that carry Salmonella is a known risk factor for the disease, especially if hands are not properly washed.[18]​​

Handling of pet food and treats also has been linked to Salmonella infection.

use of antibiotics

Using antibiotics prior to exposure to Salmonella may increase the risk of clinical illness, because the antibiotics may reduce the competitive effect of the normal intestinal flora.[50][51]

In addition, using antibiotics may heighten the risk for drug-resistant strains.[52][53]

poorly controlled diabetes mellitus

Diabetes mellitus has been noted to be a risk factor.[44][45][46]

chronic granulomatous disease

There is some evidence that patients with chronic granulomatous disease have a higher risk of Salmonella infection due to the lack of the oxidative burst.[54]

iron overload

Secondary iron overload (sickle cell disease, thalassaemia, haemolytic anaemias) places patients at higher risk.[43][55][56]​​ Sickle cell disease is often associated with joint or bone infections due to Salmonella.[57]

malnutrition

Malnutrition has been identified as a risk factor for invasive non-typhoidal salmonellosis in sub-Saharan African children.[58]

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