Salmonella Infection (Salmonellosis) Clinical Presentation

Updated: Mar 02, 2022
  • Author: Alena Klochko, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Salmonella infections typically produce 1 of 3 distinct syndromes: nontyphoidal enterocolitis, nontyphoidal focal disease, or typhoid (enteric) fever.

Nontyphoidal enterocolitis

Infection with nontyphoidal salmonellae usually causes enterocolitis similar to that caused by other bacterial enteric pathogens.

The incubation period depends on the host and the inoculum is generally 6-72 hours. In most cases, stools are loose and bloodless.

In rare cases, Salmonella infections cause large-volume choleralike diarrhea or may be associated with tenesmus. The diarrhea is typically self-limiting and resolves within 3-7 days.

Fever, abdominal cramping, chills, headache, and myalgia are common. Fever usually resolves within 48 hours.

Nontyphoidal focal disease

Focal disease is due to transient or persistent bacteremia. Almost any organ can be affected, with sites of preexisting structural abnormalities being the most vulnerable.

Although postoperative NTS infections are rare, patients with malignant brain tumors who require tumor resections and receive corticosteroids are at great risk. [29]

The diagnosis of brain abscess should be considered in all cases of NTS meningitis after surgery for brain tumor. [30] Adequate drainage (if possible), early isolation of the pathogens, and control of the infection via antibiotic therapy guided by antimicrobial susceptibility testing are vital components in preventing this potentially fatal condition. [29]


Approximately 5% of patients with NTS gastroenteritis develop bacteremia, and the incidence of extra-intestinal focal infection in patients with NTS bacteremia is about 40%. The organism can reach an extra-intestinal focus via blood dissemination, direct extension from the surrounding organs, and direct bacterial inoculation (eg, invasive medical procedures). [31]

Invasive Salmonella infection can develop even in previously healthy adults. Chronic Salmonella carriage is a predisposing factor for invasive infection, and influenza infection may contribute to such "breakthrough infections." [32] The diagnosis may be challenging since there may be no clear exposure or focal physical signs. [33]

Typhoid fever

The clinical course of typhoid fever varies greatly, ranging from fever with little other morbidity to marked multisystem toxemia.

About 10-15% of patients develop severe disease. [27]

In endemic regions, the diagnosis can be missed because of nonspecific features such as diarrhea, vomiting, or predominantly respiratory symptoms.

Typhoid fever typically has incubation period of 10-14 days and is usually associated with prolonged low-grade fever, dull frontal headache, malaise, myalgia, dry cough, anorexia, and nausea.

The fever may progress in a stepwise manner to become persistent and high grade by the end of second week. It can last up to 4 weeks if left untreated, followed by return to a normal temperature.

Relative bradycardia at the peak of the fever is an indicator of typhoid fever, although this finding is not universal.

Rose spots develop on the back, arms, and legs in up to 25% of cases late in the first week of fever. [27]

Rose spots on abdomen of a patient with typhoid fe Rose spots on abdomen of a patient with typhoid fever due to the bacterium Salmonella typhi. Courtesy of CDC/Armed Forces Institute of Pathology, Charles N. Farmer.

Coated tongue, alteration of bowel habits (varying from constipation in adults to diarrhea in children), tender abdomen, and hepatosplenomegaly are common symptoms of typhoid fever.

Malaise and lethargy can continue for a couple of months.

In areas where malaria or schistosomiasis is endemic, typhoid fever may have an atypical presentation. [28, 34]

Other presentations of Salmonella infection

Urolithiasis or structural abnormalities and immunosuppressive therapy predispose to Salmonella urinary tract infections.

Relapses can occur, even with appropriate therapy. In an Israeli series, 2.2% of patients experienced a bacteriologically proven relapse. [8] The relapse rate is significantly higher in immunosuppressed patients with Salmonella bacteremia.

Refer to Medscape article Typhoid fever for further discussion



Nontyphoidal gastroenteritis

The physical findings of nontyphoidal gastroenteritis are generally limited to nonbloody loose stool or watery diarrhea. Bloody diarrhea suggests infection with Shigella or enterohemorrhagic E coli.

Typhoid fever

Patients with typhoid fever may develop pink, blanchable, slightly raised macules (rose spots) on the chest and abdomen. However, rose spots are not diagnostic and are occasionally caused by other enteric infections. [8]

In many patients, fever is accompanied by prostration and an apathetic-lethargic state (the so-called tuphos of the ancient Greeks). In some patients, CNS symptoms, including delirium, psychosis, and focal neurological deficit, occur, without any evidence of direct CNS involvement of the infection. [35]

Headache is common and may be severe.

Abdominal tenderness (approximately 50%), mild hepatosplenomegaly (approximately 50%), and coated tongue are common in individuals with typhoid fever.

A sudden worsening of abdominal pain suggests bowel perforation.

Relative bradycardia is associated with typhoid fever but lacks specificity (also found in patients with borreliosis, malaria, or dengue fever, among others). Electrocardiographic changes, usually QT prolongation, are not uncommon but rarely evolve into a myocarditislike syndrome. [36]

While secondary pneumonia is rare, cough is common. [8]



The following were the 7 most commonly isolated Salmonella strains causing human disease reported to the US Centers for Disease Control and Prevention in 2007: [22]

  • S enteritidis (16.9%)

  • S typhimurium (16%)

  • S enteritidis heidelberg (3.9%)

  • S enteritidis newport (10.4%)

  • S enterica serotype Javiana (5.5%)

  • S enterica serotype I 4,5,12:i: (5.7%)

  • S enteritidis montevideo (3.4%)

Enteric fever is caused by S typhi and S paratyphi.



Nontyphoidal Salmonella species causes about 40% of cases of infective aortitis, which is characterized by high morbidity and mortality. [31]

Persistent Salmonella infection can lead to the development of other severe diseases such as inflammatory bowel disease (IBD) and cancer. The mechanisms by which Salmonella infection leads to colitis-associated colon cancer include (1) impaired intestinal mucosal barrier function via acute infection, (2) the effectors of the T3SS activating essential host cell pathways causing immune regulation disorders, and (3) Salmonella-associated dysbiosis. [37]