Depending upon their oxygen requirement and metabolism Cholera species are?

SJH Nursing Officer - 2019

Applied Microbiology & Infection control

Easy

Appeared in: SJH Nursing Officer - 2019

Explanation

Facultative anaerobes are organisms that can grow in the presence or absence of oxygen.
When oxygen is available, they perform aerobic respiration, which is more efficient for energy production.
In an oxygen-depleted environment, such as the human intestine, they can switch to fermentation to survive.
Vibrio cholerae exhibits this metabolic flexibility, allowing it to thrive in both contaminated water sources and the human gut, making it a classic example of a facultative anaerobe.

Option A: Obligate aerobes, such as Pseudomonas aeruginosa, absolutely require oxygen for survival and cannot grow in its absence. V. cholerae can grow without oxygen.
Option C: Obligate anaerobes, such as Clostridium tetani, are harmed or killed by the presence of oxygen. V. cholerae grows well in oxygen.
Option D: Microaerophilic organisms, like Helicobacter pylori, require a low concentration of oxygen (typically 2-10%) and are damaged by the normal atmospheric concentration of oxygen (21%). V. cholerae tolerates and grows well in atmospheric oxygen.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Bacterial metabolism and oxygen requirements as background academic context rather than a clinical decision trigger.
Understanding that V. cholerae is a facultative anaerobe is vital for laboratory diagnosis. It explains why the organism can be easily cultured under standard aerobic conditions in the lab, despite causing infection in the anaerobic environment of the gut.
This metabolic trait is a key factor in its epidemiology. It allows the bacterium to survive in various aquatic environments with fluctuating oxygen levels, facilitating its transmission through contaminated water.
What if? - If a nurse were collecting a specimen for a suspected obligate anaerobe (e.g., from a deep abscess), they would need to use a special air-free syringe and an anaerobic transport medium. Exposing the sample to air could kill the bacteria, leading to a false-negative culture result.

How to Approach the Question

This is a factual recall question testing your knowledge of microbiology.
First, identify the core of the question: What is the oxygen requirement for 'Cholera species' (Vibrio cholerae)?
Next, define the four terms provided in the options: Obligate Aerobes (need O₂), Facultative Anaerobes (flexible, with or without O₂), Obligate Anaerobes (killed by O₂), and Microaerophilic (need low O₂).
Recall the characteristics of V. cholerae. It is known to live in water (has oxygen) and cause severe diarrhea by colonizing the intestine (largely anaerobic).
This ability to live in both environments directly matches the definition of a facultative anaerobe.
Select 'Facultative Anaerobes' as the correct answer and eliminate the other options based on their strict oxygen requirements.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 1 p. 1412-1414

E6 Microbiology Essentials Sastry 4e Part 2 p. 2