Salmonella Bacteriology Question And Answers

Salmonella Long Essays

Question 1. Describe etiopathogenesis and clinical features and lab diagnosis of enteric fever.
Answer:

Enteric fever:

• Etiopathogenesis:
  • Enteric fever includes:
    • Typhoid fever – caused by salmonella typhi.
    • Paratyphoid fever – caused by salmonella paratyphi.

Virulence factors:

1. Endotoxin.

• Causes diverse toxic manifestations of enteric fever.

2. Exotoxin – enterotoxin.

3. Capsule.

• Has anti-phagocytic activity.

Enteric fever Clinical features:

• Incubation period is 7 – 14 days.
• Route of infection – contaminated food and water.

1. Typhoid fever – Its manifestations include.

• Gradual illness
• Headache
• Anorexia
• Congestion of mucous membrane.
• Hepatosplenomegaly.
• Step-ladder pyrexia.
• Relative bradycardia.
• Leucopenia.
• Skin rashes called ‘Rose-spots’ appear during the second or third week.

2. Paratyphoid fever.

• Symptoms are milder than typhoid fever.
• Septicaemia with suppurative complications occurs.

Read And Learn More: Microbiology Question and Answers

Lab Diagnosis of enteric fever:

1. Isolation of bacilli.

• For isolation of bacteria specimens are obtained from blood, feces, urine, aspirated duodenal fluid, bile, bone marrow or rose spot.
• These specimens are then cultured.

2. Demonstration of Antibodies.

• Widal test
  • It is an agglutination for the detection of agglutinins H and 0 in patients with enteric fever

• Method:
  • Equal volumes (0.4 ml) of serial dilutions of serum from 1:10 to 1: 640 and H and 0 antigens are mixed.
  • One control tube containing antigen and normal saline is used.
  • All these tubes are incubated in a water bath at 37°C.
• Results:

• Interpretation:

3. Demonstration of circulating antigen.

• Done by counterimmunoelectrophoresis and ELISA.

Salmonella Short Essays

Question 1. Diseased caused by salmonella.
Answer:

Question 2. Antigenic structure of salmonella.
Answer:

Salmonella possesses three types of antigen.