What is a classic fecal-oral transmission context and which bacteria are most characteristically spread this way?

• A. Transmission via contaminated hands or food; classic examples include Shigella, Salmonella, Campylobacter, and ETEC
• B. Transmission via airborne droplets; Mycobacterium tuberculosis
• C. Transmission via water and food; Norovirus
• D. Transmission via contaminated hands or food; classic examples include Shigella, Salmonella, Campylobacter, and ETEC

Answer: (D)

Fecal-oral transmission happens when material from feces contaminates hands, food, or water and is then swallowed, so the pathogens must be able to survive briefly outside the host and infect the gut after ingestion. The bacteria that best exemplify this route are Shigella, Salmonella, Campylobacter, and enterotoxigenic Escherichia coli (ETEC). Shigella is notorious for spreading easily in settings with close contact or poor hygiene and has a very low infectious dose, leading to dysentery after person-to-person or foodborne transmission. Salmonella and Campylobacter are major culprits in foodborne gastroenteritis, typically acquired from contaminated animal products like poultry, eggs, and dairy, with illness arising after ingestion of contaminated food. ETEC causes traveler's diarrhea and infant diarrhea and is transmitted via contaminated water or food, producing toxins that drive watery diarrhea.

Norovirus can spread through contaminated food or water as well, but it is a virus, not a bacterium, so it fits the same transmission context but not the bacterial pattern highlighted here. Airborne transmission, such as seen with Mycobacterium tuberculosis, involves a different route and is not fecal-oral.