Blood agar is a differential media since you can differentiate between different organisms based on the colony appearance. In a blood agar you are looking for hemolysis.
Based on my own test, Shigella flexneri tests negative for the citrate test.
Shigella can be dangerous during the first three years of life. It is usually effectively treated with a week to 10 days of Bactrim or Cipro. Proper hydration and sanitation of hands and food is important. Symptoms very closely mimic Salmonella food poisoning.
It sure can. It will be flat, grayish, with spreading edges.
Shigella also produce a number of toxins (Shiga toxin and others) that increase the amount of fluid secretion by the intestinal tract. This fluid secretion is a major cause of the diarrhea symptoms.
When a gram stain is done on Shigella flexneri, the cells are light pink. This means that they are gram negative.
Shigella are extremely infectious bacteria, and ingestion of just 10 organisms is enough to cause severe diarrhea and dehydration.
Food sources of transmission are: contaminated milk, ice cream, vegetables and other foods which often cause epidemics.
Shigella infection is typically via ingestion (fecal-oral contamination); depending on age and condition of the host as few as ten bacterial cells can be enough to cause an infection
Shigella accounts for about 10% of diarrhea illness in travelers to Mexico, South America, and the tropics.