Boiling water helps in killing all organism except one

UPPSC 2017

Applied Microbiology & Infection control

Easy

Appeared in: UPPSC 2017

Explanation

Spores are the dormant, highly resistant forms of certain bacteria, designed for survival in harsh conditions.
Their structure includes a tough outer coat, a dehydrated core, and high levels of calcium dipicolinate, which collectively protect them from heat, chemicals, and radiation.
Boiling water at 100°C is a method of disinfection that kills active (vegetative) microbes but is not hot enough to reliably destroy resilient bacterial spores.
Therefore, spores are the exception among the given options, as they can survive boiling.

Option A: Most fungi, including their reproductive spores (which are less resistant than bacterial endospores), are killed by boiling water within a few minutes.
Option B: This refers to the vegetative (active, growing) state of bacteria. Vegetative bacteria are readily killed by boiling at 100°C.
Option C: Protozoa, in both their active (trophozoite) and dormant (cyst) stages, are generally destroyed by boiling water. Boiling is a recommended method for disinfecting water contaminated with protozoa like Giardia and Cryptosporidium.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Microbial Control: Disinfection vs. Sterilization as background academic context rather than a clinical decision trigger.
Understanding the limitation of boiling is critical in healthcare. Medical instruments, especially those entering sterile body tissues (critical items), must be sterilized using methods like autoclaving to eliminate spores from bacteria such as Clostridium tetani (causes tetanus) or Bacillus anthracis (causes anthrax).
Boiling is considered a method of disinfection, suitable for non-critical items in a home setting (e.g., baby bottles), but it is inadequate for clinical settings where sterility is required.
What if? If an instrument used for a surgical procedure was only boiled instead of autoclaved, there would be a significant risk of postoperative infection with spore-forming bacteria, leading to severe complications like gas gangrene or tetanus.

How to Approach the Question

First, identify the keyword 'except' in the question. This indicates you are looking for the one option that does NOT fit the statement.
The statement is 'Boiling water helps in killing...'. Therefore, you need to find the organism that is NOT killed by boiling water.
Recall the principles of microbial control. Differentiate between disinfection (reduces pathogens) and sterilization (eliminates all microbial life).
Evaluate each option's resistance to heat. Fungi, vegetative bacteria, and protozoa are generally susceptible to boiling.
Recognize that bacterial spores are specifically known for their extreme resistance to heat, chemicals, and radiation, making them the correct exception.

Concept Tested & Keywords

Concept Tested: Microbial Control: Disinfection vs. Sterilization
Stem keywords: Boiling water, killing organism
Lead-in keywords: except
Negative lead-in flag: The question uses the word 'except', asking for the organism that survives boiling.

Q0thANxYtlr7icUvse6GxP

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 127-129

E6 Nursing Fundamentals Potter Perry 12e Part 2 p. 231-233