History
Obtain the patient's dietary history. Inquire about potential restaurant sources, food preparation techniques, and exposure to potentially contaminated or nonchlorinated water sources. Note: In the United States, half of Salmonella outbreaks occur in restaurant settings. [30]
Obtain the patient's travel history. Typhoid fever is increasingly associated with international travel to developing nations.
Determine if other patient contacts have similar illnesses, food ingestions, or animal contacts.
Salmonella syndromes can be divided into gastroenteritis, enteric fever, bacteremia, localized infection, and a chronic carrier state.
Gastroenteritis
Incidence is highest during May through October in temperate climates. [1]
An incubation period of 8-48 hours after the ingestion of contaminated food or water is typical, with reported incubation periods of up to 6-14 days. [31]
Symptoms are acute onset of fever and chills, nausea and vomiting, abdominal cramping, and diarrhea.
If a fever is present, it generally abides in 72 hours.
Diarrhea is usually self-limited, lasting 3-7 days and may be grossly bloody. Diarrhea lasting more than 10 days suggests another diagnosis. [1]
Enteric (typhoid) fever
Enteric fever should be considered when a febrile person (with or without diarrhea) has traveled to an endemic area, has consumed food prepared by individuals with recent exposure, or has laboratory exposure. [32]
The incubation period of enteric (typhoid) fever is 5-21 days.
Transmission is generally from contaminated water or animal products or contact with an infected person or carrier.
The initial prodrome lasting 7-10 days includes headache, cough, diaphoresis, anorexia, weakness, sore throat, malaise, abdominal pain, and constipation or "pea soup" diarrhea. Abdominal pain is present in 20-40% of patients. [1] Constipation is found in 10-38% of patients. [1]
These prodromal symptoms typically plateau as the fever increases in a stepwise fashion peaking in the second week of illness.
After the prodrome, splenomegaly, abdominal distention and pain, relative bradycardia, rash, meningismus, and mental confusion may occur. It may disseminate to lungs, gallbladder, kidneys, or CNS.
Untreated patients experience either complications or resolution by the fourth week. Intestinal perforation occurs in 3-10% of patients. [1] Other complications include endocarditis, pericarditis, pneumonitis, orchitis, and focal abscess.
Bacteremia
Bacteremia typically occurs in immunocompromised patients.
Prolonged or recurrent fevers may occur.
Focal infections may occur.
Mycotic abdominal aortic aneurysm may occur.
Localized infection
Localized infection occurs in 5-10% of persons with bacteremia. [1]
The endocardium, arteries, CNS (more commonly in infants), lungs, bones, joints, muscles, soft tissues, reticuloendothelial system, kidneys, and genital regions have all been documented sites of extraintestinal infection.
Chronic carrier state
Chronic carrier state is defined as Salmonella in the stool or urine for greater than 1 year.
A chronic carrier state has been identified in 2.2% of patients with reported nontyphoid Salmonella, lasting 30 days to 8.3 years. [33]
A chronic carrier state occurs in 1-4% of patients with untreated typhoid Salmonella.
Salmonella Typhi and Salmonella Paratyphi A are able to survive for protracted periods in the gallbladder and kidney in otherwise healthy people, resulting in long term fecal shedding. [22, 34]
Chronic Salmonella Typhi carrier state is found to be a risk factor for carcinoma of the gall bladder. [35]
Physical
Physical findings of salmonellosis can vary depending on the clinical syndrome, serotype, and patient’s immune status. However, the physical findings in gastroenteritis, enteric (typhoid) fever, and bacteremia frequently overlap.
The chronic carrier state is asymptomatic.
Gastroenteritis
Fevers (temperature 38-39°C) are common.
Physical signs of dehydration may be found.
Stool examination findings can be negative to grossly bloody.
Diffuse nonfocal abdominal tenderness is commonly present.
In rare cases, Salmonella infection mimics inflammatory bowel disease or pseudoappendicitis. [1]
Enteric or typhoid fever
A stepwise increase in temperature that plateaus in the second week at 39-40°C may be noted.
Cervical adenopathy may occur.
Relative bradycardia occurs in fewer than 50% of cases.
Abdominal examination may reveal distention with pain on deep palpation.
Hepatosplenomegaly is found in 50% of patients. [1]
A rose spot rash that typically occurs in the second week of disease is seen in 30% of patients. This rash is described as a faint salmon-colored 2-3 mm papule lesion located primarily on the trunk that fades with pressure.
Findings of meningismus may appear after the early prodrome.
Bacteremia
Bacteremia is usually associated with a prolonged or recurrent fever.
Generally, it is associated with a localized infection.
It may be a part of a mixed Salmonella infection. [1]
Causes
Currently, more than 2500 serotypes of Salmonellaenterica have been identified. [19, 9] Although clinical manifestations of each overlap, typhi and paratyphi, tend to cause enteric or typhoid fever and the more invasive form of the disease, whereas most others cause a self-limited form of gastroenteritis.
Complications
Complications of Salmonella infection may include the following:
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Urinary retention
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Metastatic abscess formation
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Acute or chronic hydrocephalus
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Psychosis
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Intestinal perforation
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Mycotic abdominal aortic aneurysm
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Nephritis
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An asymptomatic chronic carrier state
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DIC in infants with typhoid fever [36]
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Under a moderately high magnification of 8000X, this colorized scanning electron micrograph (SEM) revealed the presence of a small grouping of gram-negative Salmonella typhimurium bacteria that had been isolated from a pure culture. Image courtesy of the Centers for Disease Control and Prevention, Bette Jensen, and Janice Haney Carr.
