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Questions and Answers
Which types of Salmonella are classified as typhoidal?
Which types of Salmonella are classified as typhoidal?
What is the initial step in the pathogenesis of enteric fever?
What is the initial step in the pathogenesis of enteric fever?
After they are ingested, where do Salmonella bacteria initially invade?
After they are ingested, where do Salmonella bacteria initially invade?
Which of the following symptoms is commonly associated with enteric fever?
Which of the following symptoms is commonly associated with enteric fever?
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In the cycle of Salmonella pathogenesis, what occurs after bacteria multiply in the mesenteric lymph nodes?
In the cycle of Salmonella pathogenesis, what occurs after bacteria multiply in the mesenteric lymph nodes?
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What are the potential consequences of Salmonella re-infection of the intestinal tract?
What are the potential consequences of Salmonella re-infection of the intestinal tract?
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Which type of fever is NOT associated with Salmonella infections?
Which type of fever is NOT associated with Salmonella infections?
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How are Salmonella carried through the body after ingestion?
How are Salmonella carried through the body after ingestion?
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What is the primary cause of typhoid fever?
What is the primary cause of typhoid fever?
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Which of the following features is typically observed during the first week of enteric fever?
Which of the following features is typically observed during the first week of enteric fever?
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What is the typical incubation period for typhoid fever?
What is the typical incubation period for typhoid fever?
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What is the typical duration of gastroenteritis caused by non-typhoidal Salmonellae?
What is the typical duration of gastroenteritis caused by non-typhoidal Salmonellae?
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What percentage of untreated typhoid fever patients may become chronic carriers?
What percentage of untreated typhoid fever patients may become chronic carriers?
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Which of the following factors may prolong excretion of non-typhoidal Salmonellae after an acute illness?
Which of the following factors may prolong excretion of non-typhoidal Salmonellae after an acute illness?
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In which patient group is the risk of dehydration most significant during a Salmonella gastroenteritis infection?
In which patient group is the risk of dehydration most significant during a Salmonella gastroenteritis infection?
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Which symptom is associated with the second week of enteric fever?
Which symptom is associated with the second week of enteric fever?
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What is the primary management strategy for most cases of Salmonella gastroenteritis?
What is the primary management strategy for most cases of Salmonella gastroenteritis?
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What is a common consequence of untreated typhoid fever in the third week?
What is a common consequence of untreated typhoid fever in the third week?
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What form of treatment is recommended for chronic carriers of Salmonella typhi?
What form of treatment is recommended for chronic carriers of Salmonella typhi?
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Which complication is most likely in cases of bloodstream infection due to non-typhoidal Salmonellae?
Which complication is most likely in cases of bloodstream infection due to non-typhoidal Salmonellae?
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Which of the following is NOT a source of transmission for typhoid fever?
Which of the following is NOT a source of transmission for typhoid fever?
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Which characteristic is specific to Paratyphoid A compared to Typhoid fever?
Which characteristic is specific to Paratyphoid A compared to Typhoid fever?
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What is the first-line empiric treatment for enteric fever?
What is the first-line empiric treatment for enteric fever?
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When is blood culture most likely to yield positive results for diagnosing enteric fever?
When is blood culture most likely to yield positive results for diagnosing enteric fever?
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What is a significant drawback of the Widal test in diagnosing enteric fever?
What is a significant drawback of the Widal test in diagnosing enteric fever?
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Which of the following is NOT a precaution for preventing enteric fever?
Which of the following is NOT a precaution for preventing enteric fever?
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Which statement about chronic carriers of enteric fever is true?
Which statement about chronic carriers of enteric fever is true?
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Which species are classified as clinically important Gram-negative bacilli?
Which species are classified as clinically important Gram-negative bacilli?
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Which bacteria is responsible for causing 99% of human infections related to enteric fever?
Which bacteria is responsible for causing 99% of human infections related to enteric fever?
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What is a potential complication associated with infections caused by Salmonella and Shigella species?
What is a potential complication associated with infections caused by Salmonella and Shigella species?
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What public health measure is crucial for the prevention of enteric fever?
What public health measure is crucial for the prevention of enteric fever?
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What is one of the primary laboratory features used to identify Salmonella species?
What is one of the primary laboratory features used to identify Salmonella species?
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Why were only three of the five students affected after consuming the meal?
Why were only three of the five students affected after consuming the meal?
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What is the recommended antimicrobial treatment for infections caused by Salmonella?
What is the recommended antimicrobial treatment for infections caused by Salmonella?
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What biological role does Helicobacter pylori play in pathogenesis?
What biological role does Helicobacter pylori play in pathogenesis?
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What clinical feature is associated with infection from Shigella species?
What clinical feature is associated with infection from Shigella species?
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Which statement is true regarding the epidemiology of Salmonella species?
Which statement is true regarding the epidemiology of Salmonella species?
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What is the primary biological role of Helicobacter pylori in pathogenesis?
What is the primary biological role of Helicobacter pylori in pathogenesis?
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Which method is typically used to identify the presence of Salmonella and Shigella species in a laboratory setting?
Which method is typically used to identify the presence of Salmonella and Shigella species in a laboratory setting?
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Which of the following symptoms is most commonly associated with gastroenteritis caused by Salmonella?
Which of the following symptoms is most commonly associated with gastroenteritis caused by Salmonella?
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What is the typical incubation period for infections caused by Shigella species?
What is the typical incubation period for infections caused by Shigella species?
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In the context of Salmonella infections, which complication is most commonly associated with the infection in immunocompromised individuals?
In the context of Salmonella infections, which complication is most commonly associated with the infection in immunocompromised individuals?
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What percentage of untreated individuals with typhoid fever may become chronic carriers of Salmonella typhi?
What percentage of untreated individuals with typhoid fever may become chronic carriers of Salmonella typhi?
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What is the most likely explanation for why only three of the five students developed symptoms after a shared meal?
What is the most likely explanation for why only three of the five students developed symptoms after a shared meal?
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Which of the following is considered a first-line treatment for infections caused by Salmonella enterica?
Which of the following is considered a first-line treatment for infections caused by Salmonella enterica?
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What is a common source of contamination for eggs in non-typhoidal Salmonella infections?
What is a common source of contamination for eggs in non-typhoidal Salmonella infections?
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Which pathway primarily facilitates the transmission of non-typhoidal Salmonella from animals to humans?
Which pathway primarily facilitates the transmission of non-typhoidal Salmonella from animals to humans?
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What is the role of fimbriae in the pathogenesis of non-typhoidal Salmonellae?
What is the role of fimbriae in the pathogenesis of non-typhoidal Salmonellae?
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Which of the following statements is true regarding the epidemiology of Salmonella Gastroenteritis?
Which of the following statements is true regarding the epidemiology of Salmonella Gastroenteritis?
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What percentage of poultry is known to be contaminated with non-typhoidal Salmonella?
What percentage of poultry is known to be contaminated with non-typhoidal Salmonella?
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What is the recommended duration of antibiotic treatment for enteric fever?
What is the recommended duration of antibiotic treatment for enteric fever?
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Which type of Salmonella is primarily responsible for causing paratyphoid fever?
Which type of Salmonella is primarily responsible for causing paratyphoid fever?
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Which specimen is most likely to yield a positive culture for diagnosing enteric fever by the second week of illness?
Which specimen is most likely to yield a positive culture for diagnosing enteric fever by the second week of illness?
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What is the main limitation of the Widal test for diagnosing enteric fever?
What is the main limitation of the Widal test for diagnosing enteric fever?
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Which measure is emphasized for the prevention of enteric fever during travel to high-risk areas?
Which measure is emphasized for the prevention of enteric fever during travel to high-risk areas?
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Which antibiotic is considered the first-line empiric treatment for enteric fever?
Which antibiotic is considered the first-line empiric treatment for enteric fever?
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What percentage of patients may develop chronic carrier status after resolving symptoms of enteric fever?
What percentage of patients may develop chronic carrier status after resolving symptoms of enteric fever?
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Which type of enteric fever typically presents with less severe symptoms and rarely includes rose spots?
Which type of enteric fever typically presents with less severe symptoms and rarely includes rose spots?
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What is the role of fimbriae in the pathogenesis of enteric fever caused by Salmonella?
What is the role of fimbriae in the pathogenesis of enteric fever caused by Salmonella?
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Which organ is NOT typically invaded during the secondary bloodstream infection by Salmonella?
Which organ is NOT typically invaded during the secondary bloodstream infection by Salmonella?
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What mechanism allows Salmonella to cause necrosis of Peyer's patches?
What mechanism allows Salmonella to cause necrosis of Peyer's patches?
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How are Salmonella bacteria primarily disseminated throughout the body after initial invasion?
How are Salmonella bacteria primarily disseminated throughout the body after initial invasion?
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Which type of Salmonella is responsible for causing enteric fever specifically in humans?
Which type of Salmonella is responsible for causing enteric fever specifically in humans?
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What feature distinguishes typhoidal from non-typhoidal Salmonella in terms of host infection?
What feature distinguishes typhoidal from non-typhoidal Salmonella in terms of host infection?
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What is a significant clinical implication of Salmonella's ability to remain alive inside macrophages?
What is a significant clinical implication of Salmonella's ability to remain alive inside macrophages?
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What is the expected duration of gastrointestinal symptoms caused by non-typhoidal Salmonella infections?
What is the expected duration of gastrointestinal symptoms caused by non-typhoidal Salmonella infections?
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Which characteristic is unique to typhoidal Salmonella compared to non-typhoidal Salmonella?
Which characteristic is unique to typhoidal Salmonella compared to non-typhoidal Salmonella?
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What virulence factor of Salmonella is primarily involved in its ability to evade the host's immune response?
What virulence factor of Salmonella is primarily involved in its ability to evade the host's immune response?
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Which species of Salmonella is primarily responsible for causing gastroenteritis in both humans and animals?
Which species of Salmonella is primarily responsible for causing gastroenteritis in both humans and animals?
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Which of the following Salmonella serotypes is specifically associated with enteric fever?
Which of the following Salmonella serotypes is specifically associated with enteric fever?
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Which feature is characteristic of non-typhoidal Salmonella infections?
Which feature is characteristic of non-typhoidal Salmonella infections?
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In terms of disease causation, which of the following statements regarding Salmonella is correct?
In terms of disease causation, which of the following statements regarding Salmonella is correct?
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Which of the following groups of Salmonella is most closely linked to foodborne illness?
Which of the following groups of Salmonella is most closely linked to foodborne illness?
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Which of the following options describes a characteristic of Salmonella enterica?
Which of the following options describes a characteristic of Salmonella enterica?
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Study Notes
Salmonella
- Salmonella is a genus of bacteria belonging to the family Enterobacteriaceae
- Salmonella is divided into two species
- Salmonella bongori
- Salmonella enterica
- Salmonella enterica further categorized into subspecies
- enterica
- salamae
- arizonae
- diarizoneae
- houtenae
- indica
- Salmonella enterica is responsible for 99% of human and animal infections
- Salmonella enterica is divided into two broad categories
- Typhoidal Salmonella (humans only)
- Non-typhoidal Salmonella (humans and animals )
- Typhoidal Salmonella causes Typhoid and Paratyphoid fever.
- Non-typhoidal Salmonella causes gastroenteritis and extra-intestinal infections.
- Typhoidal Salmonella is caused by Salmonella Typhi and Salmonella Paratyphi.
- Non-typhoidal Salmonella is caused by Salmonella Enteritidis and Salmonella Dublin.
Typhoidal Salmonella
- Typhoid Fever
- caused by Salmonella Typhi
- transmitted via the faecal-oral route
- incubation period 7-21 days
- Paratyphoid Fever
- caused by Salmonella Paratyphi A, B, and C
- transmitted via the faecal-oral route
- incubation period 7-21 days
Enteric Fever
- Caused by Salmonella Typhi or Salmonella Paratyphi
- Transmitted via the faecal-oral route
- Involves three stages
- Stage 1 (week 1) - Gradual rise in temperature, headache, relative bradycardia, constipation or diarrhoea
- Stage 2 (week 2) - Fever persists (39-40°C), abdominal distension, splenomegaly, profuse ‘Pea-soup’ diarrhoea, confusion, altered mental state, Rose spots
- Stage 3 (week 3) - Hepatic, renal & bone marrow dysfunction, severe abdominal distension, perforation, peritonitis, secondary bacteraemia, osteomyelitis, relapse.
- If left untreated, enteric fever can become chronic.
- Treatment involves aggressive fluid and electrolyte replacement and antibiotic therapy.
- Commonly treated with ceftriaxone
Chronic Carriers of Salmonella Typhi
- Salmonella Typhi can persist in the digestive tract even after symptoms resolve.
- Up to 6% of patients become chronic carriers.
- Often asymptomatic but can transmit the infection indefinitely.
- Increased risk of gallbladder cancer
- Patients with chronic carriage cannot work in the food industry.
Non-Typhoidal Salmonella
- Causes gastroenteritis and extraintestinal infections.
- Symptoms of gastroenteritis include diarrhoea, nausea, headache, and malaise.
- Complications can develop, particularly in immunocompromised patients, and include bloodstream infection, systemic disease, and reactive arthritis.
Prevention of Salmonella Infections
- Hand washing
- Proper food hygiene
- Safe water sources
- Vaccination for high-risk travelers.
- WHO recommends vaccination for those traveling to high-risk areas.
Management of Non-Typhoidal Salmonella Gastroenteritis
- Fluid and electrolyte replacement and supportive care are the mainstays of treatment.
- Antibiotic therapy is typically reserved for severe or high-risk cases.
- Antibiotics may increase the length of time a patient is contagious.
Salmonella Overview
- Salmonella is a Gram-negative bacillus, it's a facultative anaerobe
- Two important types of Salmonella: Typhoidal (e.g., S.typhi) and Non-typhoidal Salmonellae (e.g., S.enteritidis)
- Typhoidal Salmonellae only infect humans and can cause enteric fever, while Non-typhoidal Salmonellae infect both humans and animals and cause gastroenteritis or extra-intestinal infections
- Typhoid and Paratyphoid are caused by Typhoidal Salmonellae
Salmonella Virulence Factors
- Adhesion
- Motility
- Intracellular Invasion
- Anti-phagocytic
- Toxin production
Enteric Fever Pathogenesis
- Ingestion through the fecal-oral route
- Adheres and penetrates the epithelium over Peyer's patches in the distal ileum using fimbriae
- Ingested by macrophages then travel via lymphatics to mesenteric lymph nodes
- Multiply in mesenteric lymph nodes and then enter the bloodstream, causing primary bacteraemia
- Invade and multiply in liver, gall bladder, spleen, bone marrow
- Re-enter the bloodstream (secondary bloodstream infection)
- Re-infect the intestinal tract from the gallbladder, leading to reinfection of mesenteric lymph nodes and Peyer’s patches
- This can cause necrosis of Peyer’s patches with associated bleeding or perforation
- Shed in stool
Enteric Fever Epidemiology
- Typhoid and paratyphoid fever are caused by Typhoidal Salmonellae
- Paratyphoid fever is similar to typhoid, but rose spots are rarely seen and the severity is lower
- Paratyphoid A is generally a diarrhoeal illness
Enteric Fever Diagnosis
- Culture and PCR of various specimens, including blood (highest in the 1st week), feces (from the 2nd week), urine (from the 3rd week), and bone marrow culture
- Widal test, an agglutination test using O or H antigens from Salmonella, is not used anymore due to its low sensitivity and specificity
Enteric Fever Treatment
- Fluid and electrolyte replacement
- Supportive management
- Antibiotics for 10-14 days
- Ceftriaxone is the first-line empiric treatment for typhoid fever, but resistance to other agents like ciprofloxacin is increasing
- Ciprofloxacin and Azithromycin can be used if susceptibility is known
- XDR typhoid fever is a major concern in Pakistan
Enteric Fever Prevention
- Public health measures, including safe drinking water and sanitary disposal of excreta
- Food hygiene, including proper storage, preparation, and hand hygiene
- Travel recommendations: boil it, cook it, peel it, or forget it!
- Vaccines are WHO recommended for those traveling to high-risk areas
Salmonella Gastroenteritis Epidemiology (Non-typhoidal Salmonellae)
- Over 2,200 different serovars
- Source: GIT of animals (poultry, reptiles, pets), environment
- Transmission: foodborne (improperly handled, inadequately cooked/stored food contaminated by animal or human fecal matter), and fecal-oral (from other humans, farms, or pets)
Salmonella Gastroenteritis Epidemiology: Food Sources
- Poultry is the most common source (up to 20% contaminated)
- Eggs, especially unpasteurized, can be contaminated from infected poultry
- Beef and beef products can be contaminated with animal intestines
- Milk, especially unpasteurized, can be infected from cow's feces
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Description
This quiz covers the essential aspects of Salmonella, including its classification, species, and the differences between Typhoidal and Non-Typhoidal Salmonella. Learn about the diseases caused by these bacteria and their transmission methods. Test your knowledge on this important topic in microbiology.
