Which of the following is a common foodborne pathogen?

• A. Escherichia coli K12
• B. Salmonella spp
• C. Lactobacillus casei
• D. Saccharomyces boulardii

Answer: (B)

The main idea here is identifying a microorganism commonly linked to illness from contaminated food. Salmonella species are well known for causing foodborne gastroenteritis and are frequently associated with outbreaks tied to poultry, eggs, dairy, and produce. Illness typically includes diarrhea, fever, and abdominal cramps after ingestion of contaminated food.

E. coli K12 is a non-pathogenic laboratory strain used in teaching and research, so it’s not considered a common foodborne pathogen in practical terms. Lactobacillus casei and Saccharomyces boulardii are probiotics used to support gut health; they’re generally safe and not associated with causing everyday foodborne illness, though rare infections can occur in extremely compromised individuals.

So, among these, the one linked to common foodborne illness is Salmonella spp.