Which serogroup of Vibrio cholerae is most virulent?

NHM UP Staff Nurse-2023 shift 1st

Applied Microbiology & Infection control

Easy

Appeared in: NHM UP Staff Nurse-2023 shift 1st

Explanation

Vibrio cholerae serogroup O1 is the most virulent and is responsible for the vast majority of epidemic and pandemic cholera outbreaks worldwide.
This serogroup produces the potent cholera enterotoxin, which leads to severe, life-threatening watery diarrhea known as "rice-water stools.".
Historically, serogroup O1 has caused all seven major cholera pandemics, including the current seventh pandemic (caused by the El Tor biotype).
While serogroup O139 can also cause epidemics, it is far less common and geographically restricted compared to O1.

Option A: Serogroup O100 is a non-O1/non-O139 strain. These strains typically do not produce cholera toxin and are associated with milder, sporadic cases of diarrhea, not large-scale epidemics.
Option C: Serogroup O5 is another example of a non-O1/non-O139 strain. It lacks the virulence factors, primarily cholera toxin, needed to cause severe, epidemic cholera.
Option D: Serogroup O150 falls into the non-O1/non-O139 category. Like other serogroups in this classification, it is not responsible for the severe, widespread outbreaks characteristic of serogroup O1.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Virulence and classification of Vibrio cholerae serogroups as background academic context rather than a clinical decision trigger.
For nurses, the immediate priority for a patient with suspected cholera is aggressive fluid and electrolyte replacement to prevent hypovolemic shock, which is the primary cause of death.
Rapidly identifying a cholera outbreak is crucial for implementing public health measures like ensuring safe water sources, promoting hygiene, and setting up treatment centers to prevent widespread transmission.
Cholera is a notifiable disease in India and globally. Nurses have a key role in ensuring prompt reporting to public health authorities to trigger an epidemiological investigation and response.

How to Approach the Question

First, identify the core of the question: it asks for the 'most virulent' serogroup of Vibrio cholerae.
Recall the microbiology of V. cholerae. The species is divided into many serogroups based on the somatic 'O' antigen.
Connect the term 'virulence' in this context to the ability to cause severe disease and large-scale epidemics or pandemics.
Remember that only two serogroups, O1 and O139, are known to cause epidemic cholera.
Recall that serogroup O1 is historically and currently the primary cause of all global cholera pandemics.
Based on this, conclude that O1 is the most virulent and epidemiologically significant serogroup, making it the correct answer.

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