Version May 2024
INTRODUCTION — Salmonellae are motile gram-negative bacilli that infect or colonize a wide range of mammalian hosts.
Salmonellae cause a number of clinical infections in humans; these include:
●Gastroenteritis
●Enteric fever (systemic illness with fever and abdominal symptoms)
●Bacteremia and endovascular infection
●Focal metastatic infections such as osteomyelitis or abscess
●An asymptomatic chronic carrier state
Enteric fever is caused by Salmonella typhi and Salmonella paratyphi; the pathogenesis, microbiology, epidemiology, clinical features, and treatment of these infections are discussed elsewhere. (See "Pathogenesis of enteric (typhoid and paratyphoid) fever" and "Enteric (typhoid and paratyphoid) fever: Epidemiology, clinical manifestations, and diagnosis" and "Enteric (typhoid and paratyphoid) fever: Treatment and prevention".)
Salmonella serotypes other than Salmonella typhi and Salmonella paratyphi are collectively known as nontyphoidal salmonellae. Issues related to the microbiology, epidemiology of nontyphoidal salmonellae are discussed separately. (See "Pathogenesis of Salmonella gastroenteritis" and "Nontyphoidal Salmonella: Microbiology and epidemiology".)
Issues related to management of patients with nontyphoidal Salmonella in a stool culture will be reviewed here. Issues related to extraintestinal infection with nontyphoidal salmonellae are discussed separately. (See "Nontyphoidal Salmonella bacteremia and extraintestinal infection".)
Acute diarrhea is also often approached syndromically, without knowledge of the causative pathogen. This approach differs somewhat by age and setting and is discussed separately. (See "Approach to the adult with acute diarrhea in resource-abundant settings" and "Approach to the adult with acute diarrhea in resource-limited settings" and "Diagnostic approach to diarrhea in children in resource-abundant settings", section on 'Acute diarrhea (typical duration <5 days)' and "Causes of acute infectious diarrhea and other foodborne illnesses in resource-abundant settings", section on 'Overview of causes'.)
EPIDEMIOLOGY — Nontyphoidal salmonellae are a major cause of diarrhea worldwide. In the United States, nontyphoidal salmonellosis is a leading cause of foodborne disease [1]. Frequently isolated serotypes include S. Enteritidis, S. Newport, and S. Typhimurium (table 1).
Salmonella is most commonly associated with the ingestion of poultry, eggs, and milk products. Other associations include fresh produce, meats, and other foods, as well as contact with pets (including reptiles) and other animals [2]. (See "Nontyphoidal Salmonella: Microbiology and epidemiology", section on 'Epidemiology'.)
Risk factors for severe infection are discussed separately (table 2). (See "Nontyphoidal Salmonella: Microbiology and epidemiology", section on 'Risk for severe disease'.)
GASTROINTESTINAL INFECTION
Clinical manifestations
Incubation period — Symptoms of Salmonella gastroenteritis typically occur within 8 to 72 hours following exposure (which usually consists of ingestion of contaminated food or water). Longer incubation periods have been reported in some outbreaks; this may be attributable to a lower bacterial dose [3,4].
General features — Gastroenteritis due to salmonellae is clinically indistinguishable from gastroenteritis caused by many other pathogens. The cardinal features include diarrhea, nausea, vomiting, fever, and abdominal cramping. A higher ingested dose of bacteria correlates with the severity of diarrhea, the duration of illness, and weight loss [5]. The diarrhea is typically not grossly bloody, although bloody stools can be seen, particularly among children [6,7]. Other constitutional symptoms (fatigue, malaise, chills) and headache are also commonly described.
Enteric infection with nontyphoidal salmonellae may be clinically mild or even asymptomatic. (See 'Asymptomatic carriage' below.)
Clinical course — Nontyphoidal Salmonella gastroenteritis is usually self-limited. Fever generally resolves within 48 to 72 hours, and diarrhea resolves within 4 to 10 days [7,8].
Mortality rates of 0.5 to 1 percent have been reported in outbreaks of S. Enteritidis, but these are most likely overestimates since milder cases tend to be unrecognized [9,10].
Following acute infection, the median duration of intermittent stool shedding is approximately five weeks. (See 'Asymptomatic carriage' below.)
Complications/invasive disease — Fewer than 5 percent of individuals with documented Salmonella gastroenteritis develop bacteremia [7,11]. Bacteremia can lead to a variety of extraintestinal manifestations such as endocarditis, mycotic aneurysm, visceral abscesses, and osteomyelitis [12]. Salmonella meningitis is a rare complication that typically occurs in neonates and children ≤1 year of age [13,14]. In addition, outbreaks of salmonellosis in neonatal intensive care units and maternity wards have been described [15,16].
Comorbidities that increase the risk of complications are discussed below. (See 'Follow-up' below.)
Some serotypes appear to be more invasive than others; however, clinical manifestations attributable to a particular serotype may be variable, geographically and temporally. Examples of serotypes associated with increased risk for bacteremia include S. choleraesuis [17,18], S. heidelberg [19,20], and antibiotic-resistant strains of S. typhimurium [11,21].
Issues related to invasive salmonellosis are discussed further separately. (See "Nontyphoidal Salmonella bacteremia and extraintestinal infection".)
Diagnosis and evaluation
Clinical approach — Nontyphoidal Salmonella gastroenteritis is generally suspected as part of the differential diagnosis of acute diarrhea, particularly when accompanied by fever or in the setting of a community outbreak.
●Stool culture – Definitive diagnosis of Salmonella gastroenteritis requires isolation of the pathogen from stool culture; however, stool cultures are not always warranted. Indications for stool cultures in a patient presenting with acute diarrhea include severe illness, immunocompromising conditions, and comorbidities that increase the risk for complications; these indications are discussed elsewhere. (See "Nontyphoidal Salmonella: Microbiology and epidemiology", section on 'Risk for severe disease'.)
●Blood culture – Among patients with known or suspected Salmonella gastroenteritis, blood cultures should be obtained in patients ill enough to require hospitalization, patients with endovascular grafts or known atherosclerosis, and patients <12 months or >50 years of age.
Laboratory tools
●Culture – Laboratory isolation of salmonellae from stool usually requires a minimum of 48 hours; 72 hours is needed if overnight enrichment broth incubation is used in addition to primary plating of stool samples.
Salmonellae are gram-negative, facultatively anaerobic Enterobacteriaceae, which are differentiated from the normal gram-negative flora of the intestinal tract, in part, by the color of the colonies on indicator plates [22].
The sensitivity and specificity of single or multiple stool cultures for diagnosis of salmonellosis are unknown.
Enrichment broths (tetrathionate or selenite) are used to facilitate the identification of Salmonella when low numbers of organisms are present. Overnight incubation in these broths inhibits the growth of Escherichia coli but not Salmonella.
●Molecular tools – Highly sensitive multiplex nucleic acid amplification tests are commercially available for detection of Salmonella and other enteric pathogens in stool samples; their clinical utility remains uncertain, especially since these tests do not provide antimicrobial resistance results [23-25]. (See "Nontyphoidal Salmonella: Microbiology and epidemiology", section on 'Microbiology'.)
Differential diagnosis — Most cases of acute diarrhea are due to infection. The other major causes of acute infectious diarrhea include viruses (eg, norovirus, rotavirus, adenoviruses, astrovirus), other bacteria (eg, Campylobacter, Shigella, Shiga-toxin producing E. coli, Vibrio, Clostridioides difficile), and protozoa (eg, cryptosporidium, giardia, cyclospora, entamoeba).
It is difficult to distinguish infections caused by the different pathogens on the basis of clinical features alone, but identifying a pathogen is not always warranted for clinical management. The differential diagnosis and approach to acute diarrhea are discussed in detail separately. (See "Approach to the adult with acute diarrhea in resource-abundant settings" and "Approach to the adult with acute diarrhea in resource-limited settings" and "Diagnostic approach to diarrhea in children in resource-abundant settings", section on 'Acute diarrhea (typical duration <5 days)' and "Causes of acute infectious diarrhea and other foodborne illnesses in resource-abundant settings", section on 'Overview of causes'.)
Management — The cornerstone of treatment of individuals with Salmonella gastroenteritis is the replacement of fluids and electrolytes. The illness is usually self-limited, and most Salmonella infections are not associated with complications.
Antimicrobial therapy may be warranted for those with severe disease or risk factors for invasive disease.
Supportive care — The most critical therapy in diarrheal illness is hydration, preferably by the oral route with solutions that contain water, salt, and sugar. This is discussed in detail elsewhere. (See "Approach to the adult with acute diarrhea in resource-abundant settings", section on 'Fluid repletion' and "Approach to the adult with acute diarrhea in resource-limited settings", section on 'Rehydration' and "Treatment of hypovolemia (dehydration) in children in resource-abundant settings".)
Antimicrobial therapy — Decisions about antimicrobial therapy are generally made empirically at the time of clinical presentation. The approach to empiric antimicrobial therapy for infectious diarrhea is discussed elsewhere. (See "Approach to the adult with acute diarrhea in resource-abundant settings" and "Approach to the adult with acute diarrhea in resource-limited settings" and "Approach to the child with acute diarrhea in resource-limited settings".)
The approach to antimicrobial therapy for patients with documented Salmonella gastroenteritis is discussed below.
Management of extraintestinal Salmonella infection is discussed separately. (See "Nontyphoidal Salmonella bacteremia and extraintestinal infection", section on 'Management'.)
Indications — Antibiotic treatment for Salmonella gastroenteritis is warranted for the treatment of patients with severe illness and for the treatment of patients at high risk for invasive disease. In these groups, the potential for improvement of severe illness and prevention of complications seems to outweigh the risks of antibiotic treatment, although this has not been definitively demonstrated in large, randomized trials.
Low risk for invasive disease
●Mild to moderate symptoms – For immunocompetent individuals between 12 months and 50 years of age with Salmonella gastroenteritis and mild to moderate symptoms, we generally do not administer antibiotic therapy since the illness is typically self-limited. Risks of treatment include the adverse effects of the antimicrobial agent (including overall antimicrobial resistance pressure) and extending the duration of asymptomatic Salmonella carriage.
This approach is supported by a meta-analysis of 12 trials that included 767 otherwise healthy individuals with nontyphoidal Salmonella gastroenteritis; there was no significant benefit from antimicrobial therapy on the duration of illness, diarrhea, or fever [26].
Short-term antibiotic use may be associated with a longer duration of stool shedding [27,28]. In a 1992 study including more than 500 patients with salmonellosis, treatment with norfloxacin was associated with a longer time to stool culture clearance compared with placebo (median 50 versus 23 days) [27]. This may be due to a deleterious effect of antibiotics on the gut microbiome, which contributes to colonization resistance and pathogen eradication.
●Severe illness — Severe illness due to Salmonella gastroenteritis is characterized by:
•Severe diarrhea (more than 9 or 10 stools per day)
•High or persistent fever
•Need for hospitalization
For immunocompetent individuals with severe illness, antimicrobial treatment is appropriate; the decision to treat should be individualized.
The presence of bloody diarrhea does not necessarily indicate the need for antimicrobial treatment. Many patients with salmonellosis have occult blood detectable in stool samples, while overtly bloody stools are more likely to be due to Shigella or enterohemorrhagic E. coli. Antibiotic treatment of diarrhea caused by enterohemorrhagic E. coli has been associated with Shiga-toxin mediated hemolytic uremic syndrome. (See "Shiga toxin-producing Escherichia coli: Clinical manifestations, diagnosis, and treatment", section on 'Antibiotics'.)
Use of antibiotics in patients with severe illness is supported by trials suggesting that empiric antimicrobial treatment of patients with severe community-acquired diarrhea improves symptoms and speeds clinical recovery by one to two days [27,29-31]. Studies included in the meta-analysis discussed above that showed minimal clinical benefit of antimicrobial treatment of nontyphoidal Salmonella gastroenteritis generally excluded patients with severe disease [26].
High risk for invasive disease — Antibiotic therapy is warranted for certain patients at high risk for complications of Salmonella intestinal infection (such as bacteremia and metastatic foci of infection), regardless of the severity of disease. Such patients include:
●Infants <12 months – Neonates with gastroenteritis, particularly those born prematurely and/or to mothers with gastroenteritis, are at risk though they may not appear toxic or acutely ill [20,32,33]. However, Salmonella meningitis is a potential complication that occurs primarily in infants and has a high case fatality rate and a significant rate of neurologic complications [34].
Infants younger than three months of age should receive antimicrobial therapy for symptomatic salmonellosis [35-37]. Some experts treat children younger than one to two years of age unless the child is afebrile and clinically improving at the time the culture results become available [32].
●Adults >50 years – Adults >50 years of age, particularly those with known atherosclerotic disease, are at higher risk of endovascular infection and aortitis if bacteremia develops. Older studies showed that approximately 10 percent of adults >50 years of age with nontyphoidal Salmonella bacteremia were found to have infective arteritis [38,39]. Those with endovascular or osseous prostheses may also reasonably be considered to have a similar risk of metastatic infection and warrant antibiotic therapy even if not severely ill with gastroenteritis.
●Patients with poorly controlled human immunodeficiency virus (HIV) infection – In two studies (one from Malawi and the other from Taiwan), 31 and 43 percent of antiretroviral-naïve adults with HIV infection developed recurrent Salmonella bacteremia [40,41]. The risk of severe and recurrent nontyphoidal salmonellosis has decreased as more HIV patients receive antiretroviral therapy [42].
●Patients with immunosuppression in the following categories:
•Organ transplant recipients
•Patients receiving corticosteroids or other immunosuppressive agents
•Patients with cancer or lymphoproliferative disease with current or recent chemotherapy
•Patients with sickle cell disease or other hemoglobinopathies
•Patients with disorders of the reticuloendothelial system, including cirrhosis
Immune compromise is an important risk factor for Salmonella bacteremia and extraintestinal infection; such patients should be evaluated carefully for these complications [43]. (See "Nontyphoidal Salmonella bacteremia and extraintestinal infection".)
●Patients with endovascular abnormalities or implanted prosthetic materials – This primarily includes patients with atherosclerotic disease, prosthetic heart valves, or prosthetic joints.
The association between these host factors and severe disease is discussed further separately. (See "Nontyphoidal Salmonella bacteremia and extraintestinal infection", section on 'Host risk factors' and "Nontyphoidal Salmonella: Microbiology and epidemiology", section on 'Risk for severe disease'.)
Empiric antibiotic selection — Given the increasing prevalence of antimicrobial resistance, local antibiotic resistance patterns must be taken into account when choosing empiric therapy. Antibiotic therapy should be tailored to susceptibility data once available. (See "Nontyphoidal Salmonella: Microbiology and epidemiology", section on 'Antimicrobial resistance'.)
●Nonpregnant adults and adolescents
•Oral therapy – Fluoroquinolones (eg, ciprofloxacin 500 mg orally twice daily or levofloxacin 500 mg orally once daily) are preferred (in the absence of contraindications) because of their activity against most common gram-negative enteric pathogens, their high tissue and intracellular concentrations, and their favorable side effect profile.
Alternative oral antibiotic agents include:
-Trimethoprim-sulfamethoxazole (160 mg/800 mg orally twice daily)
-Cefixime (400 mg orally once or twice daily)
-Azithromycin (1 gram, followed by 500 mg daily for five to seven days). It should be noted that antimicrobial resistance testing of Salmonellae for azithromycin susceptibility is not standardized and may not be performed by many laboratories.
-Amoxicillin (high dose: 1 gram orally three times daily)
•Parenteral therapy – For patients with severe disease who cannot tolerate oral therapy, an intravenous fluoroquinolone or a third-generation cephalosporin (eg, ceftriaxone 1 to 2 g intravenously once daily or cefotaxime 2 g intravenously every eight hours) may be used.
●Children
•Oral therapy – For children who do not appear ill or have evidence of disseminated infection, oral azithromycin (10 mg/kg on day 1 [maximum 500 mg], followed by 5 mg/kg [maximum 250 mg] daily for four additional days) may be given, pending blood culture results.
Alternative agents include fluoroquinolone (ciprofloxacin or levofloxacin), ampicillin, or trimethoprim-sulfamethoxazole, guided by susceptibility data.
•Parenteral therapy – For children with known or suspected serious nontyphoidal Salmonella infection, ceftriaxone (50 mg/kg intravenous [IV] or intramuscular [IM]; maximum 1 gram) should be given [35].
Duration
●Immunocompetent patients − For immunocompetent individuals with severe Salmonella gastroenteritis (in the absence of bacteremia), three to seven days of treatment is generally appropriate. This has been the range of durations evaluated in most studies of empiric treatment of severe community-acquired diarrhea [27,29-31].
For patients who are treated because of age or underlying vascular disease or the presence of implanted prosthetic devices (in the absence of severe gastrointestinal symptoms), the optimal duration is uncertain. Most experts would recommend 3 to 14 days of treatment depending upon the specific clinical situation, suspicion for bacteremia, laboratory findings, and microbiologic data.
Overall, it is prudent to limit antibiotic exposure in immunocompetent patients since antibiotic treatment has potential to paradoxically prolong carriage (see 'Asymptomatic carriage' below). In addition, antibiotic treatment confers the risks of adverse drug reactions and antibiotic resistance.
●Immunocompromised patients − We treat immunocompromised patients with salmonellosis for at least 14 days (weeks to months in some cases), with the goal of preventing persistent or relapsing infection. Decisions on the precise duration of treatment should be individualized in consultation with an expert in infectious diseases. In addition, such patients should be evaluated carefully for bacteremia or extraintestinal infection.
In a retrospective study of patients with cancer (primarily hematologic malignancies) and nontyphoidal salmonellosis, relapse occurred only among patients treated for ≤10 days [44]. (See "Nontyphoidal Salmonella bacteremia and extraintestinal infection".)
For patients with HIV infection and CD4 cell count <200 cells/microL, treatment consists of two to six weeks of antibiotics [45].
Follow-up
●Role of stool cultures
•For immunocompetent patients whose symptoms have resolved, there is no role for routine follow-up stool culture to evaluate for clearance of Salmonella. Continued short-term shedding of Salmonella following intestinal infection is common, may persist for weeks, and may be episodic.
Issues related to food handlers, healthcare workers, and childcare workers are discussed below. (See 'Food handlers, healthcare workers, and childcare workers' below.)
•Follow-up stool cultures may be informative in patients with persistent or relapsing symptoms [28] or in medically complicated or immunosuppressed patients at high risk of either recurrent/relapsed infection or bacteremia.
Such patients include:
-Patients with cancer who are receiving chemotherapy, especially if mucositis and/or neutropenia is anticipated
-Organ transplant recipients
-Patients with advanced or poorly controlled HIV infection
-Patients with prior history of relapsing gastrointestinal or bacteremic nontyphoidal salmonellosis
-Patients with prosthetic heart valves or others in whom complications of bacteremia may have serious consequences
It is reasonable to collect stool samples upon recurrence of gastrointestinal symptoms or in asymptomatic immunosuppressed patients. Samples should be obtained at least one week after discontinuation of antibiotics and at least one month after illness onset. Typically three stool samples are collected at least 24 hours apart since stool shedding may be episodic; a single negative stool culture may seem reassuring but does not ensure that the individual is no longer shedding [46].
●Treatment approach for patients with persistent or relapsing symptomatic infection
•Antibiotic therapy – For patients who warrant follow-up cultures (outlined in the preceding section above), decisions regarding further antibiotic treatment should be individualized in consultation with infectious disease expertise. Clinical considerations include patient comorbidities, current and anticipated immune status, the likelihood of serious complications related to Salmonella carriage, and a risk/benefit analysis of prolonged antimicrobial therapy (including adverse effects on the gut microbiome). Antibiotic selection should be guided by susceptibility data; the duration is generally four to six weeks.
•Novel treatment approaches – Administration of antibiotics followed by fecal transplant for eradication of antibiotic-resistant nontyphoidal Salmonella in patients with relapsing gastroenteritis has been described; this highlights the importance of a normal gastrointestinal flora in clearing salmonellosis, as well as the limitations of antibiotic therapy [47]. Another report described clearance of chronic gastrointestinal infection after administration of a symbiotic (probiotic microbes and prebiotic fructo-oligosaccharide) [48].
●Children who attend a childcare center – For children who attend a childcare center, the American Academy of Pediatrics Red Book recommends allowing children to return to care if stools are contained in the diaper, or, for toilet-trained children, when they are continent [35]. In addition, stool frequency should be no more than two stools above normal frequency for the period the child is in the program.
Pregnant patients and their neonates — Pregnant patients acquire nontyphoidal Salmonella infection at rates similar to the general population [49,50]. Pregnancy does not necessarily increase the severity of illness; however, there are case reports of pregnant patients with severe nontyphoidal Salmonella infection, and fetal loss in the setting of disseminated infection is possible in any trimester [51-53]. Transplacental transmission is possible and can precipitate preterm delivery and neonatal complications [54]. Pregnant patients with fever and gastroenteritis symptoms should be evaluated for salmonellosis as well as other enteric bacterial infections (including Listeria and Campylobacter).
Indications for treatment of pregnant patients with salmonellosis are the same as for nonpregnant patients, outlined above. (See 'Indications' above.)
Patients with peripartum infection may shed organisms during childbirth, with risk for neonatal transmission of infection [55]. Given the risk for invasive disease among neonates with salmonellosis, consideration should be given to screening cultures for both mother and infant. Timing of the mother's infection relative to delivery is an important consideration; consultation with infectious disease experts is advised.
Preventing transmission — Fecal-oral transmission is often related to poor handwashing practices; hand hygiene and careful attention to general infection control practices are the most important aspects of preventing transmission of Salmonella [56,57].
Individuals at increased risk for transmission of salmonellosis to others include food handlers, healthcare workers, and childcare workers. (See 'Food handlers, healthcare workers, and childcare workers' below.)
ASYMPTOMATIC CARRIAGE — The approach for individuals with asymptomatic carriage of nontyphoidal salmonellosis is discussed below; it differs from the approach for individuals with chronic carriage of S. Typhi, which is discussed separately. (See "Enteric (typhoid and paratyphoid) fever: Treatment and prevention", section on 'Follow-up'.)
General principles — Following acute infection, the median duration of intermittent stool shedding is approximately five weeks [46].
Chronic carriage is defined as the shedding of a Salmonella species for more than one year, as documented by an initial positive culture of a stool sample obtained at least one month after resolution of the acute illness, followed by repeat positive cultures. Chronic carriage occurs in <1 percent of patients following nontyphoidal Salmonella infection (0.2 to 0.6 percent in one study) [58]. Among patients <5 years of age, chronic carriage occurs in approximately 2.5 percent of patients. Carriage may be more common in patients with biliary tract abnormalities, especially gallstones. Chronic carriage may be identified incidentally (as part of public health follow-up), or when episodic or recurrent gastrointestinal symptoms prompt additional testing.
Food handlers, healthcare workers, and childcare workers — Food handlers, healthcare workers, and childcare workers may unknowingly shed Salmonella transiently. Such individuals may be asymptomatic or have mild, undiagnosed gastrointestinal illness with the potential to transmit infection to others at risk for severe or invasive disease.
In a report of foodborne illness in the United States between 2017 and 2019, Salmonella was the second most common pathogen associated with foodborne outbreaks related to retail food establishments [59]; however, Salmonella organisms contaminate many components of the food chain. (See "Nontyphoidal Salmonella: Microbiology and epidemiology", section on 'Foodborne infection'.)
●Prevention and infection control
•Importance of handwashing – Hand hygiene and general infection control practices are the most important aspects of preventing transmission of Salmonella. Nosocomial fecal-oral transmission is often related to poor handwashing practices [56,57]. The efficacy of proper handwashing was illustrated in one report of a foodborne outbreak of salmonellosis among nurses in which no transmission to patients occurred [60].
•No efficacy for screening asymptomatic workers – There is no evidence that screening for asymptomatic carriage is effective in reducing transmission. Furthermore, transmission from asymptomatic food handlers has only rarely been documented [61,62]. One outbreak occurred in Jordan despite routine surveillance of kitchen employees for Salmonella carriage [62].
●Quarantine
•Symptomatic workers should remain home – It is reasonable and customary for symptomatic food handlers, healthcare workers, and childcare workers to remain home from work while gastroenteritis symptoms persist; organism excretion occurs more frequently and at higher levels during symptomatic illness [63].
•Evaluation prior to returning to work – In the United States, some states require one or more negative stool cultures before such employees can return to work (see 'Follow-up' above). As national policy is not mandated, judgment should be guided by local public health requirements and individual circumstances. In the setting of a salmonellosis outbreak linked to a specific facility serving the public, health departments may have stricter or legally mandated requirements.
Obtaining stool cultures may be warranted for individuals whose work includes direct handling of food consumed without further cooking, or direct contact with immunosuppressed patients. However, it does not seem reasonable to implement this approach routinely for employees with lower risk occupations.
●Role of antibiotics for asymptomatic carriage
•No role for routine treatment – We do not routinely treat chronic asymptomatic nontyphoidal salmonella carriage in food handlers and healthcare workers. Antibiotic treatment of asymptomatic carriage is not highly effective for eradication; in contrast, it may prolong the duration of carriage as well as promote antimicrobial resistance.
In a Thai study including more than 260 food handlers with asymptomatic carriage who were randomly assigned to treatment with norfloxacin, azithromycin, or placebo, eradications were comparable [64]. In addition, antibiotic use was associated with selection of drug-resistant Salmonella.
•Treatment in select cases – For situations in which treatment is determined to be advisable by clinicians and public health authorities (examples include healthcare workers caring for immunocompromised hosts, including feeding such patients, or food handlers linked to an outbreak), antibiotic eradication may be reasonably attempted. Early, direct communication with public health authorities is advised.
-Antibiotic selection – For patients with a fluoroquinolone-susceptible isolate, treatment with ciprofloxacin (500 mg orally twice daily) or levofloxacin (500 mg orally once daily) for four weeks is reasonable.
For patients with a fluoroquinolone-nonsusceptible isolate, treatment should be guided by susceptibility data; possible regimens include high-dose amoxicillin (75 to 100 mg/kg per day) for six weeks or trimethoprim-sulfamethoxazole (160 mg/800 mg orally twice daily) for three months.
-Follow up – Three stool cultures obtained over a week, beginning at least a week after stopping antibiotics, would provide reasonable documentation of eradication.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Acute diarrhea in adults" and "Society guideline links: Acute diarrhea in children".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Salmonella infection (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Clinical manifestations – Symptoms of Salmonella gastroenteritis typically occur within 8 to 72 hours following exposure. The cardinal features include diarrhea, nausea, vomiting, fever, and abdominal cramping; these are usually self-limited. Fever generally resolves within 48 to 72 hours, and diarrhea within 4 to 10 days. (See 'Clinical manifestations' above.)
●Diagnosis and evaluation – Nontyphoidal Salmonella gastroenteritis is generally suspected as part of the differential diagnosis of acute diarrhea, particularly when accompanied by fever or in the setting of a community outbreak. Gastroenteritis due to salmonellae is clinically indistinguishable from gastroenteritis caused by other pathogens, and definitive diagnosis requires isolation of Salmonella from stool culture. (See 'Diagnosis and evaluation' above.)
●Management
•Supportive care – The cornerstone of therapy for symptomatic Salmonella gastroenteritis is hydration. (See 'Supportive care' above.)
•Role for antimicrobial therapy – The role of antibiotics depends upon the clinical setting.
For immunocompetent patients 12 months to 50 years old with mild to moderate illness due to Salmonella gastroenteritis, we suggest not routinely treating with antibiotics (Grade 2B). In such patients, antimicrobial therapy does not shorten the duration of illness and can increase the risk of extended asymptomatic Salmonella carriage. (See 'Low risk for invasive disease' above.)
For patients with severe illness (severe diarrhea, high or persistent fever, need for hospitalization) and for patients at high risk for invasive disease, the potential for antibiotics to improve disease or prevent complications appears to outweigh the risks of antibiotic use. Patients at high risk for invasive disease include:
-Infants <12 months
-Adults >50 years, especially those with known vascular disease
-Patients with poorly controlled HIV infection
-Patients with immunosuppression
-Patients with atherosclerotic disease, prosthetic heart valves, or prosthetic joints.
For these individuals, we suggest treating Salmonella gastroenteritis with antibiotics (Grade 2C). (See 'High risk for invasive disease' above.)
•Antibiotic selection – For adults and adolescents who warrant antibiotic treatment for Salmonella gastroenteritis, we favor fluoroquinolones. For children who warrant treatment, azithromycin may be used. Other appropriate antibiotic choices include trimethoprim-sulfamethoxazole or cefixime. (See 'Empiric antibiotic selection' above.)
•Antibiotic duration (see 'Duration' above)
-For immunocompetent individuals with severe Salmonella gastroenteritis (in the absence of bacteremia), three to seven days of treatment is generally appropriate.
-For immunocompetent patients who are treated because of age or underlying vascular disease, or the presence of implanted prosthetic devices (in the absence of severe gastrointestinal symptoms), 3 to 14 days of treatment is reasonable, depending upon the specific clinical situation, laboratory findings, and microbiologic data.
-For immunocompromised patients, we treat for at least 14 days (weeks to months in some cases), with the goal of preventing persistent or relapsing infection.
●Follow-up (see 'Follow-up' above)
•Role of stool cultures – For immunocompetent patients whose symptoms have resolved, there is no role for routine follow-up stool culture to evaluate for clearance of Salmonella.
Follow-up stool cultures may be informative in patients with persistent or relapsing symptoms or in medically complicated or immunosuppressed patients at high risk of either recurrent/relapsed infection or bacteremia. It is reasonable to collect stool samples upon recurrence of gastrointestinal symptoms or in asymptomatic immunosuppressed patients.
Samples should be obtained at least one week after discontinuation of antibiotics and at least one month after illness onset. Typically, three stool samples are collected at least 24 hours apart since stool shedding may be episodic.
•Treatment approach – For patients who warrant follow-up cultures, decisions regarding further antibiotic treatment should be individualized in consultation with infectious disease expertise. Clinical considerations include patient comorbidities, current and anticipated immune status, the likelihood of serious complications related to Salmonella carriage, and a risk/benefit analysis of prolonged antimicrobial therapy (including adverse effects on the gut microbiome). Antibiotic selection should be guided by susceptibility data; the duration is generally four to six weeks.
●Food handlers, healthcare workers, and childcare workers – Food handlers, healthcare workers, and childcare workers may unknowingly serve as transient Salmonella excreters. Such individuals may be asymptomatic or have mild, undiagnosed gastrointestinal illness, with the potential to transmit the infection to others at risk for severe or invasive disease. (See 'Food handlers, healthcare workers, and childcare workers' above.)
•Quarantine – Food handlers, healthcare workers, and childcare workers with symptomatic gastroenteritis should remain home from work. In the United States, some states require one or more negative stool cultures (more than 48 hours after discontinuation of antibiotics, if given) before such employees can return to work. As national policy is not mandated, judgment should be guided by local public health requirements and individual circumstances.
•Role for antibiotic therapy – For situations in which treatment is determined to be advisable by clinicians and public health authorities (examples include healthcare workers caring for immunocompromised hosts, including feeding such patients, or food handlers linked to an outbreak), antibiotic eradication may be reasonably attempted. Early, direct communication with public health authorities is advised.
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