Genus Salmonella

• What is the Gram stain result for Salmonella?

  Gram -ve
• Is Salmonella lactose positive or negative?

  Lactose -ve
• What is the indole test result for Salmonella?

  Indole -ve
• What is the urease test result for Salmonella?

  Urease -ve
• What is the phenylalanine test result for Salmonella?

  Phenylalanine -ve
• What is the H2S test result for Salmonella?

  H2S +ve
• What is the shape of Salmonella bacteria?

  Rod shaped
• Is Salmonella acid-labile or acid-stable?

  Acid-labile
• How is Salmonella motile?

  Peritrichous Flagella
• What type of intracellular lifestyle does Salmonella have?

  Facultative Intracellular in Macrophages
• What is required for Salmonella to cause infection?

  High infectious dose required
• Why is Salmonella not resistant against gastric acid?

  High infectious dose required
• What type of dissemination is possible with Salmonella?

  Haematogenous dissemination
• What are the two main pathogenic strains of Salmonella?

  Salmonella Enteritidis and Salmonella Typhi
• What is the pathogenesis of Salmonella infection?

  Ingestion → stomach → small intestine → colon → lymphatics → macrophages → blood
• Which strains does the pathogenesis apply to?

  Both S. enteritidis & S. typhi
• What is a common virulence factor of Salmonella?

  Flagellar Motility
• What is the endotoxin found in Salmonella?

  Lipopolysaccharide on outer cell membrane
• What does the endotoxin consist of?

  O antigen + lipid A
• What does the endotoxin induce in the host?

  Release of IL-1, IL-6 & TNF-alpha
• What are the symptoms induced by the endotoxin?

  Fever + hypotension
• What specimens are used for microbiological diagnosis of Salmonella?

  • Blood Cultures
  • Faeces
  • Infective Tissues
  • Urine
  • Food Products
  • Water
• What type of agar is used for Salmonella culture?

  MacConkey Agar
• What do colonies look like on MacConkey Agar?

  Transparent non-coloured colonies
• What type of agar is Hekoten Agar?

  Blue-green colonies with black centres
• What is the agglutination test for Salmonella called?

  Agglutination Type Widal
• What is mixed with the investigated serum in the Widal test?

  Known bacterial suspension of different serotypes
• What is a positive reaction titre for O-antigen in the Widal test?

  Greater than 1:100
• What is a positive reaction titre for H-antigen in the Widal test?

  Greater than 1:200
• What is a positive reaction titre for Vi-antigen in the Widal test?

  Greater than 1:10
• What is the treatment for Salmonella infections?

  Self-limiting
• What is a common antibiotic used to treat Salmonella?

  Fluoroquinolones e.g., ciprofloxacin
• What is another antibiotic used for Salmonella treatment?

  3rd Generation Cephalosporins e.g., ceftriaxone
• What is the reservoir for Salmonella Enteritidis?

  Human, Animals & Animal Products
• How is Salmonella Enteritidis transmitted?

  Consumption of contaminated food of animal origin
• What immune response is triggered by Salmonella Enteritidis?

  PMN infiltration
• What are the clinical manifestations of Salmonella Enteritidis?

  Diarrhoea, Reactive Arthritis, Salmonellosis
• What is the reservoir for Salmonella Typhi?

  Humans
• How is Salmonella Typhi transmitted?

  Ingestion of contaminated food or water
• What are the predisposing factors for Salmonella Typhi infection?

  Sickle Cell Disease