The Gastrointestinal System Question And Answers

The Gastrointestinal System

Question 1. Write a short note on typhoid.
Or
Write a short note on enteric fever.
Answer:

Term enteric fever is used to describe acute infection caused by Salmonella typhi i.e. typhoid fever or Salmonella paratyphi, i.e. Paratyphoid fever.

Typhoid Pathogenesis

• The typhoid bacilli are ingested through contaminated food or water.
• During the initial asymptomatic incubation period of about 2 weeks, the bacilli invade the lymphoid follicles and Peyer’s patches of the small intestine and proliferate.
• Following this, bacilli invade the bloodstream causing bacteremia, and the characteristic clinical features of the disease like continuous rise in temperature and ’rose spots on the skin are observed.
• Eventually, the bacilli are localized in the intestinal lymphoid tissue (producing typhoid intestinal lesions), in the mesenteric lymph nodes (leading to hemorrhagic lymphadenitis) liver(causing foci of parenchymal necrosis), the gallbladder (producing typhoid cholecystitis), and in the spleen (resulting in splenic reactive hyperplasia).

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Typhoid Pathologic Changes

These are seen in the intestines and other organs.

Intestinal lesions

Gross Features

• The terminal ileum is affected more often, but lesions may be seen in the jejunum and colon.
• Peyer’s patches show oval typhoid ulcers with long axis along the length of the bowel.
• The base of the ulcer is black due to sloughed mucosa.
• Margins of ulcers are raised slightly due to inflammatory edema and cellular proliferation.
• Regional lymph nodes are invariably enlarged.

 

Microscopically

There is the presence of hyperemia, edema, and cellular proliferation which consists of phagocytic histiocytes, lymphocytes, and plasma cells.

Typhoid Other Lesions

• The liver shows foci of parenchymal necrosis.
• Splenomegaly with reactive hyperplasia.
• Kidneys show nephritis
• Abdominal muscles show Zenker’s degeneration
• Joins undergo arthritis
• Bones show osteitis
• Meninges undergo meningitis
• Testis undergo orchitis.

Typhoid Laboratory Diagnosis

• First Week
  • Normocytic normochromic anemia, leucopenia, and albuminuria.
  • A blood culture may be positive.
• Second Week
  • Anemia and leucopenia may persist.
  • A widal test that becomes positive may show a four-fold rise in agglutinins against somatic ‘O antigen.
  • A blood culture may be positive in 50%.
• Third Week
  • Anemia and leucopenia persist. Leucocytosis occurs
  • Blood culture is positive in 30-45% of cases.
  • Positive Widal test with rising titers.
  • Positive urine and stool culture for S. typhi.
• Typhidot is a rapid test used to diagnose typhoid fever and is negative in the first week and positive thereafter.
• Indirect hemagglutination test, indirect fluorescent antibody test, ELISA for IgG and IgM antibodies to S. typhi polysaccharide, and monoclonal antibodies against S. typhi flagella have variable success rates.