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Define Typhoid Fever
An acute enteric infectious disease caused by Salmonella typhi (S.Typhi). The lesions occur in the lymphatics of the terminal ileum. Here there is proliferation of large mononuclear cells derived from the mononuclear phagocyte system (MPS) which leads to sustained fever, relative bradycardia, apathetic facial features, roseola, splenomegaly, hepatomegaly, leukopenia, intestinal hemorrhage, and intestinal perforation
What are the 4 serotypes of salmonella that cause enteric fever?
- Salmonella paratyphi A (Serogroup A)
- Salmonella paratyphi B (Serogroup B)
- Salmonella Choleraesuis (Serogroup C)
- Salmonella typhi (Serogroup D)
What kind of bacteria is Salmonella typhi?
- A gram-negative rod, with non-spore flagella.
- -facultative anaerobe
- - non-lactose fermenting
- - Produces H2S
- -Species identification with biochemical reactions
- - only reservoir is humans not animals
What are the antigens found on salmonella?
- H (flagellar antigen)
- O (somatic or cell wall antigen)
- Vi (polysaccharide virulence or surface Vi antigen)
How is salmonella typhi transmitted?
- - Fecal-oral route from human carriers (chronic infection is in the gall bladder): this can occur through close contact with patients/carriers, contaminated food and water, flies and cockroaches
- - Decreased stomach acid or impairment of mononuclear cells, such as in sickle cell disease, predisposes to Salmonella infection
For salmonella typhi infection to be pathogenic what is the usual bacterial load?
- >10^5 bacteria
- Samonella typhi is acid sensitive, so you need a lot of it to get infection
what is the first choice drug used to treat typhoid fever? Give family name and specific examples
- Quinolones ( - Floxacin)
- -highly sensitive against S.typhi
- -Penetrate well into macrophages and achieve high concentration in the bowel and bile lumes
- - Do not give to children and pregnant women (cartilage damage in young animals found)
- Drug Regimes:
- - Norfloxacin: 0.1-0.2 tid, qid/ 10-14 days
- - Ofloxacin: 0.2 tid, 10-14 d
- - Ciprofloxacin: 0.5 bid, 10d
What is the second and third choice of drug used to treat salmonella typhi?
- 2. Chloramphenicol
- - for non- multiresistent strains
- - for children, pregnant women
- - children dose: 50-60 mg/kg/d
- - adult dose: 1.5-2g/d, tid
- - after defervescence cut dose in half and complete 10-14 d course
- 3. 3rd gen Cephalosporins
- e.g. cefoperazone, ceftazidime
- -adult: 2g bid, child: 50mg/kg bid
- -10-14 d
Who was typhoid Mary?
A cook in manhattan, who contaminated the food (fecal-oral transmission)... she was a chronic carrier of salmonella typhi.
What first occurs when infected with salmonella typhi?
- Consitipation and fever, perhaps alternating with diarrhea...
- this is because infection begins in the ileocecal region