Salmonella infection (salmonellosis) is one of the most common causes of foodborne illness worldwide, with the CDC estimating 1.35 million US cases, 26,500 hospitalizations, and 420 deaths annually. The genus Salmonella contains over 2,500 serovars; non-typhoidal species (NTS) such as S.
Non-typhoidal salmonellosis (ICD-10: A02) is an intestinal and potentially invasive bacterial infection caused by Salmonella enterica serovars other than Typhi and Paratyphi. The organism is a motile gram-negative facultative anaerobe acquired primarily through ingestion of contaminated food (poultry, eggs, beef, produce, sprouts), contact with infected animals (reptiles, amphibians, backyard poultry, hedgehogs), or person-to-person fecal-oral spread. After ingestion of typically 10⁵ to 10⁸ organisms, the bacteria invade the small intestinal and colonic mucosa, enter M cells overlying Peyer patches, and trigger a neutrophilic inflammatory response with secretion-driven diarrhea. Most patients clear the infection by mucosal immunity within 4-7 days; roughly 5% develop transient bacteremia, and a smaller fraction (under 1% in healthy adults but up to 50% in HIV-infected children in sub-Saharan Africa) develop sustained invasive disease with focal complications including endocarditis, osteomyelitis, meningitis, and mycotic aneurysms.
The key symptoms of Salmonella Infection are: Diarrhea — typically watery, sometimes containing visible mucus or blood, 6-72 hours after ingestion of contaminated food, lasting 4-7 days., Abdominal cramping in the periumbilical or lower abdomen, often colicky and preceding each bowel movement., Fever, usually 38-39°C, lasting 2-3 days; higher temperatures suggest invasive disease., Nausea and vomiting in the first 24 hours, typically less severe than the diarrhea but contributing to dehydration risk., Headache and myalgia accompanying the febrile prodrome, often resembling viral gastroenteritis., Tenesmus and urgency with stool, particularly when colonic involvement predominates., Hematochezia (visible blood in stool) in roughly 5-10% of cases, more common in pediatric infection..
Most uncomplicated salmonellosis is diagnosed clinically and managed without confirmatory testing. Stool culture remains the gold standard for definitive diagnosis and serotyping, recommended when the illness is severe, prolonged beyond 5-7 days, accompanied by high fever, bloody, or occurs in high-risk hosts (infants under 3 months, immunocompromised, sickle cell disease, healthcare workers, food handlers). Molecular gastrointestinal panels (multiplex PCR) detect Salmonella DNA from stool within hours and are now widely available in US hospitals; sensitivity exceeds 95%. A positive PCR is followed by reflex stool culture to obtain an isolate for serotyping and susceptibility testing, both essential for public health surveillance and antibiotic selection. Blood cultures are obtained in any patient with high fever (over 39°C), prolonged illness, or signs of invasive disease; bacteremia is detected in roughly 5% of NTS infections overall but in a much higher proportion of infants and immunocompromised hosts. Imaging — vertebral MRI, abdominal CT with contrast, transthoracic and transesophageal echocardiography — is added when focal complications are suspected. Mycotic aortic aneurysm should be specifically excluded in any older adult with Salmonella bacteremia, especially with new back, abdominal, or flank pain. Public health reporting is mandatory in all US states, and serotyping data feed into CDC PulseNet for outbreak detection. Differential diagnoses include other invasive bacterial enteritides (Campylobacter, Shigella, enteroinvasive E. coli), Clostridioides difficile in recent antibiotic users, viral gastroenteritis (norovirus, rotavirus), and inflammatory bowel disease flares. Travel history, animal exposure, and the food consumed in the 7 days before onset guide testing intensity and outbreak investigation.
For immunocompetent adults and older children, prognosis is excellent — over 95% recover fully within 7-10 days without antibiotic therapy. Mortality from uncomplicated salmonellosis in the US is under 0.1%. Invasive non-typhoidal salmonellosis carries higher mortality: 7-10% with treatment in healthy adults, up to 25% in HIV-positive adults in resource-limited settings, and 5-15% in infants. Mycotic aortic aneurysm carries the worst prognosis — 30-day mortality 60-100% without surgery, 10-20% with combined antibiotic and surgical management. Stool shedding persists for an average of 4-5 weeks after symptom resolution without antibiotics; chronic carriage beyond one year occurs in under 1% of non-typhoidal cases (more common with typhoidal strains and biliary disease). Reactive arthritis develops in 2-15% of cases, especially in HLA-B27 carriers, with most cases resolving within 6 months but a minority becoming chronic. The dominant determinants of poor outcome are age (extremes of life), immune status, sickle cell disease, presence of prosthetic vascular grafts or joints, and delay in recognizing focal complications.
Infectious disease consultation is warranted in any case of invasive non-typhoidal salmonellosis: bacteremia, focal infection, immunocompromised host, sickle cell disease, prosthetic device involvement, or treatment failure. Mycotic aneurysm requires combined infectious disease and vascular surgery input. Pediatric ID is involved for infants under 3 months and immunocompromised children.
Find specialists →Diarrhea typically resolves over 4-7 days; fever within 2-3 days. Patients feel back to normal energy within 7-14 days. Stool shedding continues for an average of 4-5 weeks. Invasive disease requires longer treatment (2 weeks for uncomplicated bacteremia, 4-6 weeks for osteomyelitis and endocarditis) and full recovery may take 6-12 weeks. Reactive arthritis, when it occurs, peaks at 2-6 weeks and usually resolves over 3-6 months.
Rest during the acute febrile phase. Gradual return to normal activity once diarrhea, fever, and dehydration have resolved — typically within 1-2 weeks of symptom onset. Patients with reactive arthritis should avoid weight-bearing exercise on affected joints until inflammation subsides.
Most cases are managed by primary care or pediatrics. Choose a clinician familiar with the IDSA 2017 infectious diarrhea guideline who orders stool culture or PCR appropriately, avoids unnecessary antibiotics, and recognizes red flags for invasive disease. For invasive cases, look for an infectious disease physician with access to susceptibility testing and a multidisciplinary team for focal complications.
Medically reviewed by AIHealz Medical Editorial Board · May 13, 2026
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