Which organism is commonly associated with food poisoning and is a gram negative rod?

Escherichia coli, particularly certain strains like E. coli O157:H7, is well-known for causing food poisoning and is classified as a gram-negative rod. This organism can be found in contaminated food and water, especially undercooked beef and unpasteurized dairy products. E. coli produces toxins that can lead to severe gastrointestinal symptoms and other serious health complications.

The identification of E. coli as a gram-negative rod is important in microbiology because it informs medical professionals of its cellular structure, which influences its behavior in the body, its susceptibility to antibiotics, and its virulence mechanisms. The distinction of being gram-negative also means that the bacteria have a thinner peptidoglycan layer and an outer membrane containing lipopolysaccharides, which play a role in the organism's pathogenicity and immune response evasion.

In contrast, the other organisms listed have different characteristics: Clostridium is a gram-positive bacterium often associated with foodborne illnesses like botulism but not typically classified as a rod for the purposes of this context. Pseudomonas is also a gram-negative rod, but it is typically associated with opportunistic infections rather than food poisoning. Listeria, although it causes foodborne illness, is also gram