Question

Several people from a picnic came down with a gastrointestinal disturbance, and public health officials suspected a case of food poisoning. The food, especially hot dogs, were cultured and after 24 hours of growth on sheep blood agar (SBA), there was a small, round, smooth, translucent colony surrounded by a narrow zone of Beta-hemolysis. A Gram stain showed gram-positive coccobacilli. Motility medium was inoculated and an umbrella pattern of motility was observed at room temperature. What organism was isolated as the cause of the illness?

Answer 1

Answer:

Listeria monocytogenes

Explanation:

Listeria monocytogenes is a notorious food borne pathogen that causes Listeriosis. Its ability to survive at refrigeration temperature helps it evade control in food. It is has been implicated in many food borne outbreaks involving meat products.

Characteristics of Listeria

• It is a gram-positive baccilli (coccobacilli)
• It is haemolytic (shows beta-haemolysis on blood agar
• It is motile and shows an umbrella like motility when grown at room temperature

Thus, the answer is Listeria monocytogenes.