Salmonella Taxonomy and Disease Overview
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Which of the following is NOT a common source of Salmonella gastroenteritis?

  • Pasteurized milk (correct)
  • Infected eggs
  • Contaminated beef products
  • Undercooked poultry

    • What is the primary mechanism by which non-typhoidal Salmonella enters the body?

  • Inhalation of contaminated air
  • Skin absorption
  • Ingestion of contaminated food (correct)
  • Direct contact with infected surfaces

    • Which serovar is associated with both gastrointestinal and extra-intestinal infections?

  • Salmonella Virchow
  • Salmonella Typhi
  • Salmonella Dublin (correct)
  • Salmonella Enteritidis

    • What is the most significant risk factor for foodborne transmission of Salmonella?

    <p>Improperly handled or undercooked food</p> Signup and view all the answers

    What role do fimbriae play in the pathogenesis of Salmonella gastroenteritis?

    <p>Facilitating adhesion to intestinal cells</p> Signup and view all the answers

    What is a distinguishing symptom of Paratyphoid A compared to Typhoid fever?

    <p>Less severe symptoms</p> Signup and view all the answers

    Which specimen has the highest likelihood of being positive for Enteric Fever during the first week of illness?

    <p>Blood</p> Signup and view all the answers

    What is the first-line empiric antibiotic treatment for Enteric Fever?

    <p>Ceftriaxone</p> Signup and view all the answers

    Which statement best describes the Widal test for diagnosing Enteric Fever?

    <p>It has poor sensitivity and specificity.</p> Signup and view all the answers

    What is an important public health measure for preventing Enteric Fever?

    <p>Safe drinking water supply</p> Signup and view all the answers

    What is a common characteristic of chronic carriers of Enteric Fever?

    <p>They can transmit the disease even after symptoms resolve.</p> Signup and view all the answers

    For individuals traveling to high-risk areas, what is a recommended precaution regarding food?

    <p>Boil, cook, or peel food items.</p> Signup and view all the answers

    Which type of Salmonella exclusively causes human infections?

    <p>Typhoidal Salmonella</p> Signup and view all the answers

    What is the primary mode of transmission for typhoid fever?

    <p>Faecal-oral route</p> Signup and view all the answers

    Which of the following symptoms is NOT typically associated with Week 1 of untreated enteric fever?

    <p>Profuse ‘Pea-soup’ diarrhoea</p> Signup and view all the answers

    What percentage of patients may develop rose spots during Week 2 of enteric fever?

    <p>30%</p> Signup and view all the answers

    What is the potential risk faced by chronic carriers of Salmonella typhi?

    <p>Increased risk of gallbladder cancer</p> Signup and view all the answers

    Which of the following statements about the incubation period for typhoid fever is accurate?

    <p>It lasts between 7 to 21 days, possibly up to 30 days.</p> Signup and view all the answers

    What is the appropriate treatment for chronic carriers of Salmonella typhi?

    <p>Ciprofloxacin for at least 1 month</p> Signup and view all the answers

    What complications can arise in untreated patients during Week 3 of enteric fever?

    <p>Bone marrow dysfunction and osteomyelitis</p> Signup and view all the answers

    Why are chronic carriers of Salmonella typhi prohibited from working in the food industry?

    <p>They can spread the infection indefinitely</p> Signup and view all the answers

    What is the typical duration of gastroenteritis caused by non-typhoidal Salmonellae?

    <p>3-7 days</p> Signup and view all the answers

    Which of the following groups is at higher risk for severe complications from non-typhoidal Salmonellae infections?

    <p>Immunocompromised individuals</p> Signup and view all the answers

    What is the recommended management for most cases of Salmonella gastroenteritis?

    <p>Fluid and electrolyte replacement</p> Signup and view all the answers

    Which strain of non-typhoidal Salmonellae is more likely to cause bloodstream infections?

    <p>S.Dublin</p> Signup and view all the answers

    What can increase prolonged excretion of non-typhoidal Salmonellae after acute illness?

    <p>Use of antibiotics</p> Signup and view all the answers

    Which type of Salmonella is exclusively found in humans?

    <p>Salmonella typhi</p> Signup and view all the answers

    What is a common cause of gastroenteritis associated with Salmonella?

    <p>Zoonotic transmission</p> Signup and view all the answers

    What is one of the virulence factors of Salmonella?

    <p>Adhesion</p> Signup and view all the answers

    Which Salmonella serotype is most commonly associated with zoonotic infections?

    <p>Salmonella enteritidis</p> Signup and view all the answers

    What characteristic of Salmonella makes it a facultative anaerobe?

    <p>It can grow with or without oxygen.</p> Signup and view all the answers

    Which of the following is a symptom specifically associated with typhoidal Salmonella infections?

    <p>High fever</p> Signup and view all the answers

    What is the primary method of transmission for non-typhoidal Salmonella?

    <p>Contaminated food</p> Signup and view all the answers

    Which characteristic distinguishes Salmonella enterica from Salmonella bongori?

    <p>Only enterica causes enteric fever.</p> Signup and view all the answers

    Which of the following serovars is primarily associated with gastroenteritis caused by non-typhoidal Salmonella?

    <p>Salmonella Virchow</p> Signup and view all the answers

    What is the most common source of contamination leading to Salmonella gastroenteritis?

    <p>Eggs from infected poultry</p> Signup and view all the answers

    Which statement correctly describes the pathogenesis of Salmonella gastroenteritis?

    <p>Adherence to the intestinal lining is facilitated by fimbriae.</p> Signup and view all the answers

    What factor significantly contributes to the zoonotic nature of non-typhoidal Salmonella?

    <p>It is often found in the intestinal tracts of animals.</p> Signup and view all the answers

    Which method is NOT a primary mode of transmission for non-typhoidal Salmonella?

    <p>Airborne transmission</p> Signup and view all the answers

    Which of the following serotypes of Salmonella is known to cause enteric fever exclusively in humans?

    <p>Salmonella typhi</p> Signup and view all the answers

    What type of infections are associated with non-typhoidal Salmonella in humans and animals?

    <p>Gastroenteritis</p> Signup and view all the answers

    Which virulence factor of Salmonella allows it to evade the host's immune system?

    <p>Anti-phagocytic properties</p> Signup and view all the answers

    The primary transmission route for typhoidal Salmonella is through which of the following?

    <p>Fecal-oral route</p> Signup and view all the answers

    What distinguishes Salmonella enterica from Salmonella bongori?

    <p>Host specificity</p> Signup and view all the answers

    What is the most clinically significant role of Helicobacter pylori in human health?

    <p>Leads to peptic ulcer disease</p> Signup and view all the answers

    Which of the following laboratory features is indicative of Shigella

    <p>Non-lactose fermentation</p> Signup and view all the answers

    Which of the following strains of Salmonella is most commonly associated with food poisoning?

    <p>Salmonella enteritidis</p> Signup and view all the answers

    In the context of Salmonella infections, which statement regarding zoonoses is accurate?

    <p>Man can be an incidental host for zoonoses.</p> Signup and view all the answers

    What is a common source for Salmonella infections?

    <p>Undercooked poultry</p> Signup and view all the answers

    Which symptom is specifically associated with typhoidal Salmonella infections and not with non-typhoidal infections?

    <p>Rose spots</p> Signup and view all the answers

    What distinguishes Salmonella enterica from Salmonella bongori?

    <p>Salmonella enterica is more virulent in humans</p> Signup and view all the answers

    What best describes the epidemiology of Shigella infections?

    <p>Transmitted via direct contact with infected individuals</p> Signup and view all the answers

    Which of the following antimicrobial agents is typically appropriate for treating infections caused by H. pylori?

    <p>Amoxicillin</p> Signup and view all the answers

    What laboratory diagnosis method is highly accurate for identifying Salmonella infections?

    <p>PCR amplification of Salmonella DNA</p> Signup and view all the answers

    What is a common complication associated with infections caused by Salmonella species?

    <p>Dehydration</p> Signup and view all the answers

    What is the primary symptom of non-typhoidal Salmonella gastroenteritis that is usually rare in the clinical presentation?

    <p>Vomiting</p> Signup and view all the answers

    Which of the following factors is NOT associated with increased prolonged excretion of non-typhoidal Salmonellae following acute illness?

    <p>Routine antibiotic use</p> Signup and view all the answers

    What is the primary management strategy for most cases of non-typhoidal Salmonella gastroenteritis?

    <p>Hydration and electrolyte replacement</p> Signup and view all the answers

    Which complication is most commonly associated with bloodstream infections due to non-typhoidal Salmonellae?

    <p>Osteomyelitis</p> Signup and view all the answers

    What triggers multiple host inflammatory responses during a non-typhoidal Salmonella infection?

    <p>Lipopolysaccharide in the cell wall</p> Signup and view all the answers

    Which option best describes the current status of the Widal test in diagnosing Enteric Fever?

    <p>It is no longer widely used due to its low accuracy.</p> Signup and view all the answers

    What is the recommended duration of antibiotic treatment for Enteric Fever?

    <p>10-14 days</p> Signup and view all the answers

    What unexpected outcome can occur in a small percentage of patients after recovering from symptoms of Enteric Fever?

    <p>They may become chronic carriers.</p> Signup and view all the answers

    Which measure is considered essential for the prevention of Enteric Fever?

    <p>Public health measures and good hygiene practices.</p> Signup and view all the answers

    What distinguishes Paratyphoid B from other forms of Enteric Fever?

    <p>It is primarily characterized by diarrheal illness.</p> Signup and view all the answers

    Why should certain antibiotics like ciprofloxacin and azithromycin be used only when susceptibilities are known?

    <p>Due to increasing resistance in Enteric Fever cases.</p> Signup and view all the answers

    Which specimen type shows the likelihood of being positive for Enteric Fever starting from the second week of illness?

    <p>Faeces</p> Signup and view all the answers

    Which of the following public health measures is crucial for preventing the spread of Enteric Fever?

    <p>Improving hand hygiene and food preparation methods.</p> Signup and view all the answers

    Study Notes

    Salmonella Taxonomy

    • Salmonella are gram-negative bacilli
    • They are facultative anaerobes
    • There are two main groups: Typhoidal Salmonellae, and Non-typhoidal Salmonellae.
    • Typhoidal Salmonellae only infect humans
    • Non-typhoidal Salmonellae infect both humans and animals
    • Typhoidal Salmonellae are responsible for Enteric fevers, such as Typhoid fever, Paratyphoid fever
    • Non-typhoidal Salmonellae cause Gastroenteritis and Extra-intestinal infections
    • They are classified by subspecies Salmonella enterica and Salmonella bongori
    • Salmonella enterica is further classified into 6 subspecies, Salmonella bongori has no subspecies

    Typhoidal Salmonellae

    • Salmonella typhi causes Typhoid fever
    • Salmonella paratyphi A, B, and C cause Paratyphoid fever which is less severe than Typhoid fever
    • They transmit via the fecal-oral route
    • Common routes of transmission are from a chronic carrier, or contaminated food or water
    • Typhoidal Salmonellae have an incubation period of 7-21 days, but can last up to 30 days
    • Typhoid fever has a global incidence of 22 million cases per year
    • It is most prevalent in underdeveloped areas with poor sanitation
    • Travellers to endemic countries have the highest risk of infection

    Enteric Fever Clinical Features

    • Enteric fever progresses in three clinical stages, each lasting about a week
    • Stage 1: Gradual increasing body temperature, headache, relative bradycardia, constipation or diarrhea
    • Stage 2: Elevated temperature, abdominal distension, splenomegaly, profuse diarrhea , confusion, mental state changes, ‘rose spots’ on the flanks, buttocks, and costal margins
    • Stage 3: Complications such as hepatic, renal, and bone marrow dysfunction, severe abdominal distension, perforation, peritonitis, secondary bacteraemia, osteomyelitis, and relapse
    • Stage 4: Improvement in fever, mental state, and abdominal distension, however intestinal complications may still occur

    Typhoid Fever Chronic Carriage

    • Chronic carriage is defined as positive stool cultures 12 months after overcoming the disease
    • Up to 6% of patients become chronic carriers
    • They can transmit S. typhi indefinitely
    • Most carriers are asymptomatic, however they have an increased risk of gallbladder cancer

    Paratyphoid Fever

    • Paratyphoid fever is similar to Typhoid fever, however patients rarely see ‘rose spots’ and it is less severe
    • Paratyphoid B is classified as a diarrheal illness

    Salmonella Gastroenteritis (Non-typhoidal Salmonellae)

    • There are over 2,200 different serovars
    • The source of infection is the gastrointestinal Tract (GIT) of animals, reptiles (pets), and the environment
    • Transmission occurs through foodborne and fecal-oral routes
    • Foodborne transmission occurs through improperly handled, inadequately cooked, or unrefrigerated food contaminated by animal or human fecal material
    • Fecal-oral transmission occurs through contact with other humans, at farms, or via contact with pets

    Food sources of Non-typhoidal Salmonellae

    • Poultry: most common source, up to 20% contaminated
    • Eggs: infected poultry, oviduct infected and eggs contaminated by transovarian spread
    • Beef and beef products: meat contaminated in the abattoir from the animal's intestines
    • Unpasteurized milk: infected from cow's feces

    Salmonella Gastroenteritis Pathogenesis

    • Ingestion of Salmonella leads to adherence via multiple genes and fimbriae
    • Invasion is a key step, inducing nonphagocytic cells such as enterocytes to internalize bacteria
    • Salmonella then survives and replicates within the modified phagosome
    • Virulent strains of Salmonella induce multiple host inflammatory responses and cytokines mediated by lipopolysaccharide in the cell wall

    Salmonella Gastroenteritis: Clinical Features

    • Onset is abrupt, short course, self-limiting gastroenteritis typically lasting 3-7 days
    • Symptoms include Diarrhea, nausea, headache, malaise
    • Vomiting is rare
    • Severe infection with dehydration is a problem in extremes of age and immunocompromised patients

    Non-typhoidal Salmonella Chronic Excretion

    • Chronic excretion can last up to 4 weeks after acute illness
    • Prolonged excretion is increased by antibiotics, HIV, inflammatory bowel disease, and diverticulosis

    Non-typhoidal Salmonella Complications

    • Bloodstream infection (BSI) occurs in 4% of cases
    • Systemic disease includes osteomyelitis, meningitis, and endovascular and prosthetic material infections
    • Reactive arthritis can occur

    Management of Salmonella Gastroenteritis

    • Fluid and electrolyte replacement is the only treatment required for most cases
    • Antibiotics are not routine, but are used for severe illness and high risk of invasive disease

    Salmonella enterica: subspecies

    • Salmonella enterica subsp. enterica: Cause 99% of human and animal infections
    • Salmonella enterica subsp. arizonae: Non-typhoidal Salmonellae
    • Salmonella enterica subsp. salamae: Non-typhoidal Salmonellae
    • Salmonella enterica subsp. diarizonae: Non-typhoidal Salmonellae
    • Salmonella enterica subsp. houteni: Non-typhoidal Salmonellae
    • Salmonella enterica subsp. indica: Non-typhoidal Salmonellae

    Typhoidal Salmonellae: Subspecies

    • Salmonella enterica subsp. enterica serovar Typhi: Causes Typhoid Fever
    • Salmonella enterica subsp. enterica serovar Paratyphi: Causes Paratyphoid Fever

    Non-typhoidal Salmonellae: Serotypes

    • Salmonella enterica subsp. enterica serovar Typhimurium: Causes gastroenteritis
    • Salmonella enterica subsp. enterica serovar Virchow: Causes gastroenteritis
    • Salmonella enterica subsp. enterica serovar Enteritidis: Causes gastroenteritis
    • Salmonella enterica subsp. enterica serovar Dublin: Causes gastroenteritis

    Salmonella Diagnosis

    • Culture and PCR of blood, feces, urine, and bone marrow are recommended for diagnosis
    • The Widal test was the mainstay of diagnosis for decades, but is no longer used due to poor sensitivity and specificity

    Salmonella Treatment

    • Fluid and electrolyte replacement is vital for most cases
    • Antibiotics: Ceftriaxone is the first line treatment, resistance is increasing for other drugs such as ciprofloxacin, azithromycin
    • Chronic carriers are at risk after recovering from Typhoid fever

    Salmonella Prevention

    • Public health measures: Safe drinking water and sanitary disposal of excreta
    • Precautions: Good food hygiene, hand hygiene
    • Vaccination: WHO recommends vaccination for those traveling to high-risk areas

    Salmonella

    • Salmonella species are facultative anaerobic Gram-negative bacilli
    • Most human and animal infections are caused by Salmonella enterica
    • There are two main groups: Typhoidal Salmonella and Non-typhoidal Salmonella
    • Typhoidal Salmonella is limited to human hosts, includes S. Typhi and S. Paratyphi
    • Non-typhoidal Salmonella includes S. Enteritidis, S. Typhimurium, S. Dublin, and other strains
    • Non-typhoidal Salmonella can infect both humans and animals

    Typhoidal Salmonella

    • Typhoidal salmonella causes enteric fever
    • Humans are the only hosts
    • Typhoid fever can be severe and potentially fatal if left untreated
    • Typhoid fever is characterized by high fever, headache, abdominal pain, and constipation
    • Typhoid carriers can occur after symptoms have resolved, posing a risk of transmission

    Non-Typhoidal Salmonella

    • Non-typhoidal Salmonella can cause a range of symptoms, including gastroenteritis, bacteremia, and extra-intestinal infections
    • Non-Typhoidal Salmonella gastroenteritis is often associated with food poisoning
    • The most common symptoms of gastroenteritis are nausea, vomiting, diarrhea, and abdominal cramps
    • The illness is usually self-limiting, resolving within 3-7 days
    • Complications include bacteremia, osteomyelitis, meningitis and reactive arthritis

    Virulence Factors for Typhoidal and Non-Typhoidal Salmonella

    • Salmonella have a variety of virulence factors that contribute to their pathogenicity
    • These include:
      • Adhesion
      • Motility
      • Intracellular invasion
      • Anti-phagocytic mechanisms
      • Toxin production

    Epidemiology of Typhoidal Salmonella

    • Typhoid fever is endemic in many developing countries, primarily in Asia, Africa, and Latin America
    • Transmission occurs through the fecal-oral route, often from contaminated food or water
    • It is essential to have safe drinking water and proper sanitation to prevent transmission

    Epidemiology of Non-Typhoidal Salmonella

    • Non-Typhoidal Salmonella infections are common worldwide, with over 2,200 serovars identified
    • The most common sources are poultry, eggs, and beef products
    • Transmission is often foodborne, through inadequately cooked, handled, or stored food
    • Fecal-oral transmission can also occur from infected humans, animals, or pets

    Diagnosis of Typhoidal Salmonella

    • Diagnosis is made by culture and PCR of various specimens, including blood, feces, urine, and bone marrow
    • Blood cultures are most likely to be positive in the first week of illness
    • Widal tests are no longer routinely used due to poor sensitivity and specificity

    Diagnosis of Non-Typhoidal Salmonella

    • Diagnosis of Non-Typhoidal Salmonella infections is typically made by culture of stool specimens

    Treatment of Typhoidal Salmonella

    • First-line treatment for Typhoid fever is intravenous ceftriaxone
    • Fluoroquinolones, such as ciprofloxacin, can also be used, but resistance is increasing
    • Chronic carriers may require prolonged antibiotic treatment

    Treatment of Non-Typhoidal Salmonella Gastroenteritis

    • Most cases of Non-Typhoidal Salmonella gastroenteritis are self-limiting and do not require antibiotics
    • Oral rehydration therapy is crucial to prevent dehydration
    • Antibiotic therapy is reserved for severe cases, particularly in high-risk individuals
    • The choice of antibiotics depends on the specific serovar and susceptibility patterns

    Prevention of Typhoidal Salmonella

    • Prevention of Typhoidal Salmonella infection relies on public health measures, including safe drinking water, proper sanitation, and hygiene practices
    • Vaccines are available for individuals travelling to high-risk areas

    Prevention of Non-Typhoidal Salmonella

    • Prevention of Non-Typhoidal Salmonella infections can be achieved through good food hygiene practices, including thorough cooking of poultry and meat, proper handwashing, and safe handling of foods
    • Adequate sanitation and hygiene in food preparation and handling areas are essential to minimize transmission

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    Description

    Explore the fascinating world of Salmonella with a focus on its taxonomy and the diseases caused by Typhoidal and Non-typhoidal Salmonellae. This quiz covers important classifications, transmission routes, and the associated diseases like Typhoid fever and Gastroenteritis. Test your knowledge and learn more about these significant pathogens.

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