What are the values of temperature and time employed for autoclave in a routine bacteriological laboratory?

AIIMS Bhuvneshwar NO- 2018

Applied Microbiology & Infection control

Easy

Appeared in: AIIMS Bhuvneshwar NO- 2018

Explanation

The standard for routine steam sterilization (autoclaving) is achieving a temperature of 121°C.
This temperature is maintained for a duration of 15 to 30 minutes, with 30 minutes being common for laboratory media and waste to ensure full penetration.
These conditions are achieved using saturated steam at a pressure of approximately 15 pounds per square inch (psi).
This combination of moist heat and pressure effectively denatures essential proteins and enzymes, killing all microorganisms, including highly resistant bacterial spores.

Option A: This temperature is too high for a standard steam autoclave cycle and is more aligned with dry heat sterilization, which would require a much longer duration.
Option B: These parameters (132°C for 8 minutes) describe a 'flash' or pre-vacuum sterilization cycle, not a routine one.
Option D: This temperature is below the required threshold for sterilization. It is insufficient to reliably kill bacterial endospores.

Visual 1: Diagram - A labeled diagram of a laboratory autoclave, showing the chamber, jacket, pressure gauge, safety valve, and control panel. This helps learners visualize the equipment being discussed.
Visual 2: Chart - A comparison chart showing the time and temperature requirements for different sterilization methods, including steam autoclave (gravity and pre-vacuum), dry heat oven, and chemical sterilization. This provides a broader context.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Principles of sterilization by autoclaving as background academic context rather than a clinical decision trigger.
Proper autoclave operation is a fundamental skill for infection control, crucial for preventing healthcare-associated infections (HAIs) by ensuring that surgical and medical instruments are sterile.
In a laboratory setting, correct sterilization prevents the contamination of experiments and diagnostic cultures, which is essential for accurate patient results and research integrity.
Quality assurance is vital. Nurses and technicians must use chemical indicators in each pack and biological indicators (spore tests) regularly (e.g., weekly) to verify that the autoclave is functioning correctly and achieving sterility.

How to Approach the Question

First, identify the key terms in the question: 'autoclave', 'temperature and time', and 'routine bacteriological laboratory'. This specifies the method and context.
Recall the standard principle of autoclaving: using moist heat (steam) under pressure to achieve sterilization.
Remember the benchmark temperature for killing highly resistant bacterial spores, which is 121°C.
Evaluate the given options. Immediately discard any option with a temperature significantly below 121°C (like 110°C) as it's insufficient for sterilization.
Differentiate between routine cycles and special cycles. The 121°C cycle is the standard for 'routine' work. Higher temperatures like 132°C are for 'flash' cycles, which are faster but have specific applications.
Select the option that matches the standard temperature (121°C) with a typical time frame for routine laboratory loads (15-30 minutes).

Concept Tested & Keywords

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