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Questions and Answers
What is the primary characteristic of Salmonella in terms of morphology?
What is the primary characteristic of Salmonella in terms of morphology?
- Gram negative cocci
- Gram negative rods (correct)
- Gram positive rods
- Gram positive cocci
Which type of antigen is used to identify different serovars of Salmonella?
Which type of antigen is used to identify different serovars of Salmonella?
- Capsular antigen
- Nucleic acid antigen
- Protein 'A' antigen
- Flagellar protein 'H' antigen (correct)
What is one disease caused by Salmonella?
What is one disease caused by Salmonella?
- Colitis
- Pneumonia
- Typhoid fever
- Salmonellosis (correct)
How do S.Typhimurium and S.Typhi primarily differ in their pathogenicity?
How do S.Typhimurium and S.Typhi primarily differ in their pathogenicity?
Which of the following host categories is NOT typically associated with Salmonella?
Which of the following host categories is NOT typically associated with Salmonella?
Which characteristic describes the genetic distance of Salmonella enterica from its relatives?
Which characteristic describes the genetic distance of Salmonella enterica from its relatives?
What is the older species name for Salmonella Typhimurium?
What is the older species name for Salmonella Typhimurium?
What role does the lipopolysaccharide 'O' antigen play in Salmonella?
What role does the lipopolysaccharide 'O' antigen play in Salmonella?
What is the typical presentation of Salmonella Typhi infection?
What is the typical presentation of Salmonella Typhi infection?
Which of the following serovars is most frequently associated with gastroenteritis?
Which of the following serovars is most frequently associated with gastroenteritis?
What is the global burden of typhoid fever estimated at annually?
What is the global burden of typhoid fever estimated at annually?
In which part of the body does non-typhoidal Salmonella primarily site its infiltration?
In which part of the body does non-typhoidal Salmonella primarily site its infiltration?
What distinguishes the clinical picture of non-typhoidal Salmonella infections from that of Salmonella Typhi?
What distinguishes the clinical picture of non-typhoidal Salmonella infections from that of Salmonella Typhi?
What is a characteristic feature of the systemic infection caused by Salmonella?
What is a characteristic feature of the systemic infection caused by Salmonella?
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Study Notes
Salmonella Overview
- Salmonella is a genus of Gram-negative rod bacteria.
- Two primary surface antigens identify different Salmonella serovars: Lipopolysaccharide “O” antigen and Flagellar protein “H” antigen.
Classification and Morphology
- Salmonella enterica is the primary species associated with human infections.
- The naming system includes designations like Salmonella enterica serovar Typhimurium (previously known as Salmonella Typhimurium).
Modes of Infection
- Salmonella causes a broad clinical spectrum of diseases, including:
- Enteric Fever: Systemic infection with a carrier state.
- Gastroenteritis: Infection limited to the gastrointestinal tract.
- Invasive Infections: Involves blood stream infections.
Global Burden of Disease
- Typhoid fever results in approximately 9.2 million cases and 110,000 deaths annually.
- Non-typhoidal Salmonella infections account for about 93.8 million cases and 155,000 deaths each year.
Causative Agents
- Enteric Fevers: Mainly caused by Salmonella enterica serovars Typhi and Paratyphi A.
- Gastroenteritis: Primarily due to Salmonella enterica serovars Typhimurium and Enteritidis, with Enteritidis being the most frequent.
Clinical Presentation
-
Salmonella Typhi Symptoms:
- Diarrhea occurs in one-third of patients, but is not typical.
- Characterized by mononuclear infiltrate in various organs.
-
Non-Typhoidal Salmonella Symptoms:
- Symptoms are typically diarrheal and self-limiting.
- Massive neutrophil (PMN) infiltration is observed in patients with diarrhea.
Pathology and Infiltration
- Salmonella Typhi Infiltration: Primarily in the small intestine and other organs, with scarce PMNs in stool.
- Non-Typhoidal Salmonella Infiltration: Mainly in the terminal ileum and colon, with numerous PMNs detected in stool.
Host Range and Genetic Diversity
- Salmonella can infect a range of hosts, including humans, birds, mammals, and cold-blooded vertebrates.
- Genetic distinction is noted, with some serovars being non-pathogenic to humans.
Salmonella Survival and Persistence
- Various features influence the bacterium's ability to survive and persist in different environments.
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