Which of the following enteric pathogens has the LOWEST infective dose, permitting efficient person-to-person transmission?

• A Vibrio cholerae
• B Enterotoxigenic E. coli
• C Salmonella typhi
• D Shigella species ✓

Explanation

Shigella requires only about 10 to 100 organisms to cause disease, the lowest infective dose among the major enteric bacteria. This acid tolerance allows the organism to survive gastric transit, and it explains why shigellosis spreads readily by direct fecal-oral contact, fomites, and flies rather than only through contaminated food and water. Cholera and ETEC typically need 10^6 to 10^8 organisms because large numbers are destroyed by gastric acid.

Reference: Ananthanarayan and Paniker Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.