Efficiency of dry heat is tested using:

AIIMS BHOPAL NO- 2018( Shift-2nd)

Microbiology

Easy

Appeared in: AIIMS BHOPAL NO- 2018( Shift-2nd)

Explanation

The question asks for the biological indicator used to test the efficacy of dry heat sterilization.
Biological indicators use highly resistant microorganisms to challenge a sterilization process.
Clostridium tetani is a bacterium that produces endospores, which are extremely resistant to heat and desiccation.
Among the given choices, the spores of Clostridium tetani represent the most significant challenge to a dry heat process, making it the most suitable answer.

Option B: Corynebacterium diphtheriae is a non-spore-forming bacterium and is easily killed by heat. It is not resistant enough to be used as a biological indicator for sterilization.
Option C: Spores of Mucor are fungal spores. While more resistant than vegetative bacteria, they are significantly less heat-resistant than bacterial endospores like those from Clostridium or Bacillus species.
Option D: Bordetella pertussis is a delicate, non-sporing bacterium that is very sensitive to heat, drying, and disinfectants. It would be destroyed long before effective sterilization conditions are met.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Biological indicators for dry heat sterilization as background academic context rather than a clinical decision trigger.
Proper sterilization of medical equipment is a cornerstone of infection control in healthcare, directly impacting patient safety by preventing healthcare-associated infections (HAIs).
Nurses have a critical responsibility to ensure that all instruments and devices used for patient care, especially those used in invasive procedures, are properly sterilized. Understanding the principles of sterilization monitoring helps ensure the equipment is safe to use.
What if the sterilization method was moist heat (autoclave) instead of dry heat? The correct biological indicator would be the spores of Geobacillus stearothermophilus, which are specifically chosen for their high resistance to saturated steam under pressure.

How to Approach the Question

First, identify the key terms in the question: 'Efficiency,' 'dry heat,' and 'tested using.' This points to the concept of sterilization validation.
Recall that testing a sterilization process requires a 'biological indicator'—an organism that is highly resistant to that specific process.
Recognize that the most heat-resistant life forms are bacterial endospores.
Evaluate the options provided. Identify which of the organisms are spore-formers versus non-spore-formers.
Eliminate the non-sporing bacteria (Corynebacterium, Bordetella) and the less-resistant fungal spores (Mucor).
Select Clostridium tetani as the correct answer because it is the only option that forms highly resistant endospores suitable for challenging a sterilization process.

Concept Tested & Keywords

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E6 Microbiology OneStop Sastry p. 50-52

E6 Microbiology Applied AnjuDhir 3e Part 1 p. 147-149