Final answer:
A stool specimen can be suspected of Vibrio cholera if it possesses toxin, as cholera is caused by Vibrio cholerae that produces a characteristic toxin leading to severe diarrhea. Culturing on selective media and molecular testing are commonly used in its diagnosis.
Step-by-step explanation:
A stool specimen can be suspected of Vibrio cholera if it possesses toxin. This is because cholera is caused by the bacterium Vibrio cholerae, which is known for its symptoms related to the production of the cholera toxin (CT). The toxin leads to an increase in chloride ion secretion into the gut lumen, followed by water, causing the characteristic watery diarrhea of cholera. Various diagnostic methods can be used to identify the presence of Vibrio cholerae in a stool specimen, including culturing on selective media like TCBS agar to produce distinct yellow colonies, and molecular testing for the presence of DNA sequences encoding specific virulence factors.
Other methods such as microscopic examination for the presence of cysts, trophozoites, or oocysts are commonly used to diagnose parasitic infections and would not typically be expected to yield results pointing towards a cholera infection, which is bacterial in nature and does not present with these forms.