Sterilization by steam under pressure is carried at the temperature between

KGMU 2024

Microbiology

Easy

Appeared in: KGMU 2024

Explanation

Sterilization by steam under pressure (autoclaving) requires temperatures above the normal boiling point of water to kill all microorganisms, including highly resistant bacterial spores.
The effective operational temperature range for autoclaves is generally between 108°C and 147°C.
This range encompasses the two most common standard sterilization cycles: 121°C and 134°C.
The increased pressure inside the autoclave is what allows water to heat to these high temperatures, creating saturated steam that denatures microbial proteins.

Option A: This temperature range is too low for effective steam sterilization. While above the boiling point of water, it is not high enough to reliably kill bacterial spores in a standard cycle time.
Option B: This temperature range corresponds to boiling at atmospheric pressure. Boiling is a method of disinfection that kills most vegetative bacteria but is ineffective against heat-resistant bacterial spores.
Option D: Similar to the other low-temperature options, this range is insufficient to achieve sterility. It does not reach the critical temperature of 121°C needed to ensure the destruction of all microbial life.

Visual 1: Diagram: A labeled diagram of a hospital autoclave, showing the chamber, jacket, pressure gauge, temperature display, and safety valve. This helps visualize the equipment used for steam sterilization.
Visual 2: Chart: A pressure-temperature chart for water, illustrating how increasing the pressure raises the boiling point, which is the core principle of autoclaving.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Temperature range for steam sterilization (autoclaving) as background academic context rather than a clinical decision trigger.
Proper autoclaving is a cornerstone of infection control in all healthcare settings, preventing surgical site infections and the transmission of pathogens via contaminated instruments.
Nurses are responsible for ensuring that items are correctly prepared, loaded, and processed in the autoclave, and for verifying that each cycle has met the required parameters using chemical and biological indicators.
What if? If a biological indicator (spore test) from an autoclave cycle comes back positive, it signifies a sterilization failure. All items from that load must be considered non-sterile, recalled, and reprocessed. The autoclave must be taken out of service and investigated for malfunction.

How to Approach the Question

First, identify the key terms in the question: 'sterilization' and 'steam under pressure'. Recognize that this refers to autoclaving.
Recall that sterilization is a process that kills all forms of microbial life, including spores, which requires high temperatures.
Remember that 'steam under pressure' allows water to be heated to temperatures well above its normal boiling point of 100°C.
Evaluate the options. Eliminate any ranges that are at or near 100°C, as these are insufficient for killing spores (disinfection, not sterilization).
Select the option that includes the standard autoclaving temperatures, which are typically 121°C and 134°C. The range of 108°C to 147°C correctly encompasses these critical temperatures.

Concept Tested & Keywords

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