The El Tor biotype of Vibrio cholerae O1 which caused the 7th pandemic has a characteristic that distinguishes it from the Classical biotype in terms of clinical presentation and cultural characteristics. Which of the following is CORRECT about El Tor biotype?
- A El Tor produces more severe disease and is Voges-Proskauer (VP) negative
- B El Tor produces relatively milder disease, is VP positive, and is haemolysin-producing (haemolysin of El Tor) ✓
- C El Tor is VP negative, produces classical rice water stools, and is sensitive to Polymyxin B
- D El Tor and Classical biotypes are clinically indistinguishable and share identical cultural characteristics
Correct answer: B. El Tor produces relatively milder disease, is VP positive, and is haemolysin-producing (haemolysin of El Tor)
Explanation
El Tor biotype of V. cholerae O1 characteristically: (1) produces relatively milder disease with a higher carrier-to-case ratio, (2) is Voges-Proskauer (VP) positive (produces acetoin from glucose), (3) produces haemolysin (El Tor haemolysin, haemolyses sheep/goat RBCs), (4) is resistant to Polymyxin B (Classical is sensitive), and (5) agglutinates chicken RBCs. The Classical biotype is VP negative, haemolysin-negative, and Polymyxin B sensitive. El Tor causes the current (7th) pandemic.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.