Which of the following pathogens is classified as a bacterial infection?

Salmonella is classified as a bacterial infection because it is caused by bacteria belonging to the genus Salmonella, which are known to cause foodborne illnesses. These bacteria can be found in a variety of foods, particularly raw or undercooked poultry, eggs, and sometimes dairy products. When ingested, Salmonella can lead to symptoms such as diarrhea, fever, and abdominal cramps. The fact that it is a bacterial pathogen is significant in food safety because it highlights the importance of proper food handling and cooking practices to prevent contamination and illness.

In contrast, Listeria, while also a bacterial pathogen, is not the correct choice in this context if Salmonella is highlighted. Norovirus and Giardia are not classified as bacterial infections; Norovirus is a viral pathogen causing gastroenteritis, and Giardia is a protozoan parasite causing gastrointestinal issues. This distinction is crucial for understanding how different types of pathogens affect food safety and public health.