Salmonella typhi, which is a gram-negative rod, has a very interesting and well known story. The story is that of The Tragic Case of Typhoid Mary. The classic example of a chronic carrier was the woman known as "Typhoid Mary," a cook in New York City and Long Island in the early part of this century. This woman who worked as a cook for a number of institutions infected a large number of people. Thankfully by epidemiological investigations of a number of the typhoid cases Mary was found to be the likely source of the outbreaks. They did tests to prove that she was a carrier and it was proven. She remained a carrier for years, partly because her gall bladder was infected and continuously secreted the organisms into her intestine. After numerous attempts to make her have surgery she refused and was sentenced to jail time but was released after three years on the promise that she would not cook in restaurants anymore. She promptly disappeared, changed her name and began cooking again. Years later she was captured and sent to prison for 23 years. This was 32 years total after they found out she was a carrier.
It is frequently necessary to detect the presence of specific microorganisms associated with disease or poor sanitation with selective media. Bismuth sulfite agar is the choice medium used to isolate the gram-negative Salmonella typhi from feces. An electron micrograph of a metal-shadowed whole cell of it also shows a flagella and fimbrae. A single cell is about 0.9um in diameter. Salmonella typhi is the most virulent species. This pathogen crosses the intestinal wall and enters the bloodstream. The incubation period is much longer than that of salmonellosis, normally about two weeks. The patient first suffers from a high fever of 104 F and continual headache. Diarrhea appears only during the second or third week, and the fever tends to decline. The organism becomes disseminated in the body and can be isolated from the blood, urine, and feces. Treatment is that of third-generation cephalosporins, such as ceftriaxone. However, drug sensitivity testing is required because of the continuing appearance of resistant strains. Chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole are among the effective alternatives. Recovery from typhoid confers a life-long immunity.
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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