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Questions and Answers
Which of the following is NOT a common source of Salmonella gastroenteritis?
Which of the following is NOT a common source of Salmonella gastroenteritis?
What is the primary mechanism by which non-typhoidal Salmonella enters the body?
What is the primary mechanism by which non-typhoidal Salmonella enters the body?
Which serovar is associated with both gastrointestinal and extra-intestinal infections?
Which serovar is associated with both gastrointestinal and extra-intestinal infections?
What is the most significant risk factor for foodborne transmission of Salmonella?
What is the most significant risk factor for foodborne transmission of Salmonella?
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What role do fimbriae play in the pathogenesis of Salmonella gastroenteritis?
What role do fimbriae play in the pathogenesis of Salmonella gastroenteritis?
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What is a distinguishing symptom of Paratyphoid A compared to Typhoid fever?
What is a distinguishing symptom of Paratyphoid A compared to Typhoid fever?
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Which specimen has the highest likelihood of being positive for Enteric Fever during the first week of illness?
Which specimen has the highest likelihood of being positive for Enteric Fever during the first week of illness?
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What is the first-line empiric antibiotic treatment for Enteric Fever?
What is the first-line empiric antibiotic treatment for Enteric Fever?
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Which statement best describes the Widal test for diagnosing Enteric Fever?
Which statement best describes the Widal test for diagnosing Enteric Fever?
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What is an important public health measure for preventing Enteric Fever?
What is an important public health measure for preventing Enteric Fever?
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What is a common characteristic of chronic carriers of Enteric Fever?
What is a common characteristic of chronic carriers of Enteric Fever?
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For individuals traveling to high-risk areas, what is a recommended precaution regarding food?
For individuals traveling to high-risk areas, what is a recommended precaution regarding food?
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Which type of Salmonella exclusively causes human infections?
Which type of Salmonella exclusively causes human infections?
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What is the primary mode of transmission for typhoid fever?
What is the primary mode of transmission for typhoid fever?
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Which of the following symptoms is NOT typically associated with Week 1 of untreated enteric fever?
Which of the following symptoms is NOT typically associated with Week 1 of untreated enteric fever?
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What percentage of patients may develop rose spots during Week 2 of enteric fever?
What percentage of patients may develop rose spots during Week 2 of enteric fever?
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What is the potential risk faced by chronic carriers of Salmonella typhi?
What is the potential risk faced by chronic carriers of Salmonella typhi?
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Which of the following statements about the incubation period for typhoid fever is accurate?
Which of the following statements about the incubation period for typhoid fever is accurate?
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What is the appropriate treatment for chronic carriers of Salmonella typhi?
What is the appropriate treatment for chronic carriers of Salmonella typhi?
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What complications can arise in untreated patients during Week 3 of enteric fever?
What complications can arise in untreated patients during Week 3 of enteric fever?
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Why are chronic carriers of Salmonella typhi prohibited from working in the food industry?
Why are chronic carriers of Salmonella typhi prohibited from working in the food industry?
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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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Which of the following groups is at higher risk for severe complications from non-typhoidal Salmonellae infections?
Which of the following groups is at higher risk for severe complications from non-typhoidal Salmonellae infections?
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What is the recommended management for most cases of Salmonella gastroenteritis?
What is the recommended management for most cases of Salmonella gastroenteritis?
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Which strain of non-typhoidal Salmonellae is more likely to cause bloodstream infections?
Which strain of non-typhoidal Salmonellae is more likely to cause bloodstream infections?
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What can increase prolonged excretion of non-typhoidal Salmonellae after acute illness?
What can increase prolonged excretion of non-typhoidal Salmonellae after acute illness?
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Which type of Salmonella is exclusively found in humans?
Which type of Salmonella is exclusively found in humans?
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What is a common cause of gastroenteritis associated with Salmonella?
What is a common cause of gastroenteritis associated with Salmonella?
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What is one of the virulence factors of Salmonella?
What is one of the virulence factors of Salmonella?
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Which Salmonella serotype is most commonly associated with zoonotic infections?
Which Salmonella serotype is most commonly associated with zoonotic infections?
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What characteristic of Salmonella makes it a facultative anaerobe?
What characteristic of Salmonella makes it a facultative anaerobe?
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Which of the following is a symptom specifically associated with typhoidal Salmonella infections?
Which of the following is a symptom specifically associated with typhoidal Salmonella infections?
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What is the primary method of transmission for non-typhoidal Salmonella?
What is the primary method of transmission for non-typhoidal Salmonella?
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Which characteristic distinguishes Salmonella enterica from Salmonella bongori?
Which characteristic distinguishes Salmonella enterica from Salmonella bongori?
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Which of the following serovars is primarily associated with gastroenteritis caused by non-typhoidal Salmonella?
Which of the following serovars is primarily associated with gastroenteritis caused by non-typhoidal Salmonella?
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What is the most common source of contamination leading to Salmonella gastroenteritis?
What is the most common source of contamination leading to Salmonella gastroenteritis?
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Which statement correctly describes the pathogenesis of Salmonella gastroenteritis?
Which statement correctly describes the pathogenesis of Salmonella gastroenteritis?
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What factor significantly contributes to the zoonotic nature of non-typhoidal Salmonella?
What factor significantly contributes to the zoonotic nature of non-typhoidal Salmonella?
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Which method is NOT a primary mode of transmission for non-typhoidal Salmonella?
Which method is NOT a primary mode of transmission for non-typhoidal Salmonella?
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Which of the following serotypes of Salmonella is known to cause enteric fever exclusively in humans?
Which of the following serotypes of Salmonella is known to cause enteric fever exclusively in humans?
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What type of infections are associated with non-typhoidal Salmonella in humans and animals?
What type of infections are associated with non-typhoidal Salmonella in humans and animals?
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Which virulence factor of Salmonella allows it to evade the host's immune system?
Which virulence factor of Salmonella allows it to evade the host's immune system?
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The primary transmission route for typhoidal Salmonella is through which of the following?
The primary transmission route for typhoidal Salmonella is through which of the following?
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What distinguishes Salmonella enterica from Salmonella bongori?
What distinguishes Salmonella enterica from Salmonella bongori?
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What is the most clinically significant role of Helicobacter pylori in human health?
What is the most clinically significant role of Helicobacter pylori in human health?
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Which of the following laboratory features is indicative of Shigella
Which of the following laboratory features is indicative of Shigella
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Which of the following strains of Salmonella is most commonly associated with food poisoning?
Which of the following strains of Salmonella is most commonly associated with food poisoning?
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In the context of Salmonella infections, which statement regarding zoonoses is accurate?
In the context of Salmonella infections, which statement regarding zoonoses is accurate?
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What is a common source for Salmonella infections?
What is a common source for Salmonella infections?
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Which symptom is specifically associated with typhoidal Salmonella infections and not with non-typhoidal infections?
Which symptom is specifically associated with typhoidal Salmonella infections and not with non-typhoidal infections?
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What distinguishes Salmonella enterica from Salmonella bongori?
What distinguishes Salmonella enterica from Salmonella bongori?
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What best describes the epidemiology of Shigella infections?
What best describes the epidemiology of Shigella infections?
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Which of the following antimicrobial agents is typically appropriate for treating infections caused by H. pylori?
Which of the following antimicrobial agents is typically appropriate for treating infections caused by H. pylori?
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What laboratory diagnosis method is highly accurate for identifying Salmonella infections?
What laboratory diagnosis method is highly accurate for identifying Salmonella infections?
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What is a common complication associated with infections caused by Salmonella species?
What is a common complication associated with infections caused by Salmonella species?
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What is the primary symptom of non-typhoidal Salmonella gastroenteritis that is usually rare in the clinical presentation?
What is the primary symptom of non-typhoidal Salmonella gastroenteritis that is usually rare in the clinical presentation?
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Which of the following factors is NOT associated with increased prolonged excretion of non-typhoidal Salmonellae following acute illness?
Which of the following factors is NOT associated with increased prolonged excretion of non-typhoidal Salmonellae following acute illness?
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What is the primary management strategy for most cases of non-typhoidal Salmonella gastroenteritis?
What is the primary management strategy for most cases of non-typhoidal Salmonella gastroenteritis?
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Which complication is most commonly associated with bloodstream infections due to non-typhoidal Salmonellae?
Which complication is most commonly associated with bloodstream infections due to non-typhoidal Salmonellae?
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What triggers multiple host inflammatory responses during a non-typhoidal Salmonella infection?
What triggers multiple host inflammatory responses during a non-typhoidal Salmonella infection?
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Which option best describes the current status of the Widal test in diagnosing Enteric Fever?
Which option best describes the current status of the Widal test in diagnosing Enteric Fever?
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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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What unexpected outcome can occur in a small percentage of patients after recovering from symptoms of Enteric Fever?
What unexpected outcome can occur in a small percentage of patients after recovering from symptoms of Enteric Fever?
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Which measure is considered essential for the prevention of Enteric Fever?
Which measure is considered essential for the prevention of Enteric Fever?
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What distinguishes Paratyphoid B from other forms of Enteric Fever?
What distinguishes Paratyphoid B from other forms of Enteric Fever?
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Why should certain antibiotics like ciprofloxacin and azithromycin be used only when susceptibilities are known?
Why should certain antibiotics like ciprofloxacin and azithromycin be used only when susceptibilities are known?
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Which specimen type shows the likelihood of being positive for Enteric Fever starting from the second week of illness?
Which specimen type shows the likelihood of being positive for Enteric Fever starting from the second week of illness?
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Which of the following public health measures is crucial for preventing the spread of Enteric Fever?
Which of the following public health measures is crucial for preventing the spread of Enteric Fever?
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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.
