Salmonella typhi
Members of genus salmonella cause disease including gastroenteritis and enteric typhoid fever.
Typhoid fever caused by salmonella typhi.
Morphology
Gram negative bacilli, Non-sporing, rod- shaped, motile and non capsulated bacilli.
Size; 2.4 micrometre X 0.6 micrometre in size.
Characteristics
Aerobic and facultative anaerobic.
Produce colonies of 2-3 micrometre in diameter, circular.
Grow at 37 degree Celsius temperature, PH 7.8
Grow readily on simple and enriched media blood sugar, macConkey medium.
Sources and Modes of Transmission
Contaminated water and food
Fecal oral route
Inhalation
Direct contact
Chronic carriers
Pet turtles and rats
Pathogenesis
Enteric fever/typhoid fever
Gastroenteritis or food poisioning
Septicemia; invasion of blood stream
Cause vascular salmonella infection, abdominal infection.
1. Enteric fever/ Typhoid fever
Caused by salmonella typhi and salmonella paratyphi A, B,C.
Typhoid fever; salmonella typhi
Paratyphoid fever; salmonella paratyphi A, B,C
Typhoid fever
This infection caused by ingestion through contaminated food and water.
Incubation period is usually 7-14 days.
Mild pyrexia, skin, rashes, anorexia, sore throat, diarrhea, focal infection, intestinal hemorrhage.
Abdominal cramping
Laboratory Diagnosis
Specimen examination
1. In 1st week; blood culture and PCR helpful in lab diagnose.
2. In second week; serological test
Widal test
ELISA
3. In 3rd week
Faeces culture
4. In 4th week
Urine culture
Specimen collection
Cultural characteristics and culture
Isolation of bacilli
Gram staining and microscopic examination
Show gram -ve rods (red colour)
Biochemical test
Salmonella typhi and salmonella paratyphi ferment glucose, mannitol and produce only gas.
Treatment
Antibiotics like ciprofloxacin, furazolidone, chloramphenicol and ampicillin are effective.
Enteric fever treated by cholecystectomy.
Prevention/ Prophylaxis
Administered TAB (Typhoid A and B) vaccines by parenteral route but recently oral vaccine also prepared.
Improve sanitary condition in surrounding.
Safe water supply and hygiene handing of food and drinks.
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