Home > Colon > Salmonella (typhoid and nontyphoidal)
Colon
Infectious colitis
Salmonella (typhoid and nontyphoidal)

Elliot Weisenberg, M.D.

Topic Completed: 1 November 2015

Minor changes: 30 September 2020

Copyright: 2003-2021, PathologyOutlines.com, Inc.

PubMed Search: Salmonella [title] colon

Elliot Weisenberg, M.D.
Page views in 2020: 4,174
Page views in 2021 to date: 1,075
Table of Contents
Definition / general | Essential features | Terminology | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Prognostic factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Differential diagnosis | Additional references
Cite this page: Weisenberg E. Salmonella (typhoid and nontyphoidal). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colonsalmonella.html. Accessed April 19th, 2021.
Definition / general
  • Disease caused by Salmonella species infection
  • While overlap exists, species causing typhoid fever and nontyphoidal species are often categorized separately
Essential features
  • Salmonellosis is considered a food borne disease
  • Typhoid fever:
    • Sometimes known as enteric fever, is a life threatening illness caused by Salmonella typhi sometimes called Salmonella enterica serotype Typhi or S. paratyphi
    • Infects from 20 to 30 million people a year, mostly in the developing world
    • In industrialized countries, it is usually encountered in travelers
  • Nontyphoid species:
    • Usually cause acute, self limited gastroenteritis
    • The Centers for Disease Control and Prevention (CDC) estimates that one million cases, 19,000 hospitalizations, and 450 deaths occur each year in the United States
    • Tens of millions of cases occur worldwide each year causing an estimated 100,000 deaths
    • Disease is spread through ingestion of contaminated food or water, most often in a sporadic fashion but sometimes through foodborne outbreaks that often are associated with suboptimal sanitary practices or food preparation
Terminology
  • Salmonella is named after the veterinarian Elmer Daniel Salmon
  • Salmonella are gram negative rods
  • Salmonella species bacteria are serotyped based on the chemical content of the O antigens found on the surface and the protein content of part of the flagella known as the H antigen
  • Over 2500 serotypes have been described; however, under 100 are known to be associated with human disease
  • Serotyping is currently done by molecular methods
  • S. typhi and S. paratyphi are associated with typhoid fever
  • Some of the more common nontyphoidal species are:
    • S. enteritidis
    • S. typhimurium
    • S. muenchen
    • S. adnatum and S. give
    • S. paratyphi may also cause nontyphoidal disease
Epidemiology
  • Worldwide over 20 million cases of typhoid fever occur each year, mostly in the developing world
  • Approximately 1800 cases of typhoid fever occur in the United States annually, mostly in travelers
  • From 1.0 to 1.2 million cases of nontyphoidal illness occur in the United States each year, causing about 19,000 hospitalizations and 450 deaths
  • Tens of millions of nontyphoidal illness occur worldwide, causing over 100,000 deaths each year
  • Disease occurs from ingestion of bacteria, usually in food or water, eggs, milk, meat, poultry
  • Vegetables contaminated with animal feces are commonly implicated
  • Food borne outbreaks, often associated with less than sanitary conditions, are common sources of disease
    • However, in the United States approximately 60% of cases occur sporadically
  • Fecal oral transmission may occur; disease after contact with infected animals is another source
  • Salmonellosis is a common cause of traveler diarrhea
  • All serotypes at least in theory may cause human disease
  • Serotypes may or may not be host specific
  • When serotypes specific to other species infect humans. severe disease may result
  • S. typhi is restricted to humans
  • Risk factors for infection include:
    • Lack of access to clean water
    • Poor sanitation. especially regarding food handling
    • Flooding
    • Ingestion of plants fertilized with sewage
    • Urban environments
    • Sexual transmission has been reported
  • Both typhoidal and nontyphoidal salmonellosis may occur in health care workers when proper hand hygiene is not practiced
  • Travelers to the developing world are often infected with S. paratyphi; vaccination against S. typhi is common prior to travel
Sites
  • S. typhi may infect the entire gastrointestinal tract but typically is found in the terminal ileum, appendix and ascending colon; nontyphoidal Salmonella infects the small and large bowel
  • S. typhi typically spreads to the liver, spleen, bone marrow and lymph nodes
  • Extraintestinal spread is uncommon in nontyphoidal Salmonella but may occur with severe disease
Pathophysiology
  • Salmonella possess cellular mechanisms enabling bacterial proteins to be transferred to enterocytes and M cells with subsequent growth within endosomes
  • Subsequent events include an inflammatory response with neutrophil recruitment and mucosal damage
  • The host immune response typically controls nontyphoidal infection; however, the very young, elderly, debilitated and immunosuppressed may lack the response necessary to control infection
  • S. typhi more commonly invades M cells
  • Bacteria are phagocytosed by histiocytes in underlying lymphoid tissue
  • The bacteria proliferate and widely disseminate through blood vessels and lymphatic channels
Etiology
  • Salmonella are gram negative bacilli
  • S. typhi is found only in humans
  • Nontyphoidal species are found in humans, domestic and wild animals
  • In general, infection occurs through ingestion of contaminated food or water or the fecal-oral route
  • Nontyphoidal Salmonella are commonly found in food and companion animals including poultry, cattle, swine, parrots, cats, dogs and turtles
  • Eggs, milk, meat, poultry and contaminated vegetables are commonly implicated
  • Direct person to person transmission as well as transmission from pets may occur
    • In this setting, the source of the transmission may not appear ill
Clinical features
  • Symptoms of nontyphoidal salmonellosis generally start 12 - 36 hours after ingestion of bacteria but may occur after 6 - 72 hours
  • Ingestion of very few organisms may cause disease
  • Typically patients suffer self limited illness characterized by diarrhea, abdominal pain, fever, nausea and occasionally vomiting that is unpleasant but rarely life threatening
  • May be life threatening In infants, elderly, immunocompromised or debilitated patients, due to dehydration or dissemination of bacteria
  • Very rarely, toxic megacolon may complicate infection
  • Individuals with achlorhydria or hypochlorhydria from drugs, chronic Helicobacter pylori infection or other causes are at higher risk of infection
  • Some patients develop a reactive arthritis that may last for months and lead to chronic arthritis

  • Typhoid fever causes symptoms shortly after bacteria are ingested
  • Patients suffer from severe abdominal pain, bloody diarrhea, bloating, anorexia, nausea, vomiting, headache
  • A brief asymptomatic period is followed by bacteremia with fever and flu-like illness
  • Blood cultures are almost always positive at this time and antibiotic therapy may be lifesaving
  • With disease progression in untreated patients, high fever and abdominal pain occurs that may mimic appendicitis; lasts for about two weeks
  • If patients survive, symptoms slowly abate
  • Possible extraintestinal complications include CNS disease, endocarditis, myocarditis, pneumonia, cholecystitis, osteomyelitis (patients with sickle cell disease are particularly prone to osteomyelitis)
  • Disease relapses may occur
Diagnosis
  • Nontyphoidal salmonellosis traditionally has been diagnosed by stool culture although many patients do not seek medical attention
  • Recently a PCR based assay has been introduced that, in addition to Salmonella species bacteria, also detects Camplyobacter group, Shigella species, Vibrio group, Yersinia enterocolitica, Shiga toxin 1 and 2, Norovirus G1 / GII, Rotavirus A and Aeromonas species
  • Serotyping is done to characterize disease outbreaks
  • Typhoid fever is diagnosed by blood or stool culture
  • In the developing world where laboratory facilities may not be readily available, disease may be treated empirically
Prognostic factors
  • Nontyphoidal salmonellosis is almost always a self limited infection, except in infants, the elderly, immunocompromised and debilitated patients
  • Antibiotic therapy is usually efficacious in these patients, although antibiotic resistance is a growing problem
  • Without treatment, typhoid fever may be lethal even in healthy individuals but the prognosis is worse in infants, the elderly, immunocompromised and debilitated patients
  • Prompt initiation of antibiotic therapy greatly improves patient outcome; although again, antibiotic resistance is a growing problem
Case reports
Treatment
  • Nontyphoidal Salmonella usually:
    • Only requires supportive care, particularly hydration
    • Antibiotics are indicated for severe disease and vulnerable patients
    • Ceftriaxone and ciprofloxacin are currently recommended by the CDC
    • Antibiotic resistance is a growing problem
  • Antibiotic therapy for typhoid fever is obligatory and should not be delayed for confirmatory laboratory testing
    • In the past, chloramphenicol, trimethoprim-sulfamethoxazole, cephalosporins and first generation fluoroquinolones were used but antibiotic resistance developed
    • Currently, third generation fluoroquinolones are recommended but resistance has been reported
    • Surgery may be necessary for intestinal perforation or gallbladder disease
    • An effective vaccine for S. typhi exists
  • WHO recommendations for the public and travelers include:
    • Ensure food is properly cooked and hot when served
    • Avoid raw milk and products made from raw milk
    • Avoid ice unless made from safe water
    • Use disinfecting tablets for water unless its purity is certain
    • Wash hands thoroughly with soap and water after contact with pets or farm animals and after using the toilet
    • Wash fruits and vegetables thoroughly and if possible, peel fruits and vegetables unless optimal sanitary practices are known to have taken place
  • Recommendations for food handlers and producers include:
    • Maintain a clean workspace
    • Separate raw and cooked food
    • Cook food thoroughly
    • Keep food at safe temperatures
    • Use safe water and raw materials
    • Practice good personal hygiene
    • Do not work if have fever, diarrhea, vomiting or infected skin lesions
    • Protect fields from animal contamination
Gross description
  • Colonoscopy in patients with mild nontyphoidal salmonellosis shows nonspecific findings including edema and petechial hemorrhage; more severe disease is associated with friability and ulceration
  • Typhoid fever causes marked enlargement of Peyer patches and lymphoid tissue in the appendix and ascending colon leading to mucosal elevation along the axis of the ileum
  • Perforation may occur
  • Small gray, soft nodules (typhoid nodules) may be present in the liver
  • There is splenomegaly and lymphadenopathy
Microscopic (histologic) description
  • Nontyphoidal salmonellosis is rarely biopsied
  • The findings are a non-specific acute self limited colitis
  • The crypt architecture is maintained, there are increased mixed inflammatory cells within the lamina propria in a patchy distribution with foci of cryptitis and possible crypt abscesses
  • Long standing cases may demonstrate architectural distortion raising the spectre of idiopathic inflammatory bowel disease
    • This is also true of S. typhimurium infection
  • Knowledge of culture results is necessary to render a specific diagnosis

  • S. typhi shows neutrophils, histiocytes with cytoplasmic bacteria, nuclear debris and hemorrhage within the lamina propria associated with a lymphoplasmacytic infiltrate
  • The spleen and lymph nodes show sinus histiocytosis that distorts the normal architecture
  • Typhoid nodules in the liver show aggregates of histiocytes with necrotic debris
  • Typhoid nodules may also be found in bone marrow and lymph nodes
Microscopic (histologic) images

Contributed by Elliot Weisenberg, M.D.
Missing Image   Missing Image

Acute self limited colitis



Images hosted on other servers:
Missing Image

Typhoid nodules

Differential diagnosis
  • The differential diagnosis of nontyphoidal salmonellosis includes other enteric pathogens that cause acute self limited colitis including Shigella and Campylobacter
  • Long standing cases may mimic idiopathic inflammatory bowel disease
Back to top
Home > Colon > Salmonella (typhoid and nontyphoidal)
Image 01 Image 02