**Question:** All the following statements about V. cholera 0139 are true, except:

A. V. cholera serogroup O139 is a newly emerged strain that causes gastroenteritis and diarrhoea.
B. V. cholerae O139 is resistant to multiple antibiotics like chloramphenicol, ampicillin, and tetracycline.
C. Infection with V. cholerae O139 is rare and primarily affects immunocompromised individuals.
D. V. cholerae O139 is more virulent than V. cholerae O1 El Tor and classical strains.

**Correct Answer:** C. Infection with V. cholerae O139 is rare and primarily affects immunocompromised individuals.

**Core Concept:** Vibrio cholerae O139 is a serogroup of Vibrio cholerae, a Gram-negative bacterium responsible for causing cholera, a severe dehydrating diarrheal disease. V. cholerae O139 is a newly emerged strain, which emerged in South Asia in the late 1990s, following the emergence of V. cholerae O1 El Tor in the 1960s. Both strains are responsible for causing epidemic cholera pandemics.

**Why the Correct Answer is Right:** The statement "Infection with V. cholerae O139 is rare and primarily affects immunocompromised individuals" is incorrect. While V. cholerae O139 is indeed a less common strain compared to O1 El Tor, it is not limited to immunocompromised individuals. Both O1 and O139 strains can affect individuals with normal immune systems as well.

**Why Each Wrong Option is Incorrect:**

**A. Infection with V. cholerae O139 is resistant to multiple antibiotics like chloramphenicol, ampicillin, and tetracycline.**
- Chloramphenicol, ampicillin, and tetracycline are antibiotics used to treat cholera. However, this statement is not entirely correct. V. cholerae O139 strains may exhibit antibiotic resistance, but they are not exclusively resistant to these three antibiotics. The statement suggests that all O139 strains are resistant to these antibiotics, which is not the case.

**B. Vibrio cholerae O139 is more virulent than Vibrio cholerae O1 El Tor and classical strains.**
- The correct statement is that V. cholerae O139 is less virulent than the classical and El Tor strains. The O139 strain is less virulent due to genetic mutations that occurred during the emergence of this strain.

**C. Infection with Vibrio cholerae O139 is rare and primarily affects immunocompromised individuals.**
- As mentioned earlier, both O1 and O139 strains can affect individuals with normal immune systems. This statement is incorrect as it suggests that O139 primarily affects immunocompromised individuals, which is not accurate.

**D. Vibrio