Ethylene oxide (EtO) sterilant spectrum: EtO gas is used to destroy which classes of microbes during low-temperature sterilization?

Introduction:
Ethylene oxide (EtO) is a potent alkylating agent used for low-temperature sterilization of heat- and moisture-sensitive medical devices. Understanding its antimicrobial spectrum helps justify its use when steam sterilization is unsuitable.

Given Data / Assumptions:

• EtO reacts with proteins, DNA, and RNA, disrupting replication and metabolism.
• Sterilization implies lethality against spores in addition to vegetative forms.

Concept / Approach:
EtO exhibits broad microbicidal activity against vegetative bacteria, bacterial spores, fungi, and many viruses when cycles are properly validated (concentration, humidity, temperature, time) and followed by adequate aeration to remove residues. Therefore, the option reflecting broad coverage is correct.

Step-by-Step Solution:
Identify the target spectrum required for sterilization: includes spores. Confirm EtO’s alkylating action across diverse microorganisms. Select the comprehensive option “All of these.”

Verification / Alternative check:
Standards and guidelines (e.g., ISO/ANSI/AAMI) recognize EtO as a sterilant with validated sterility assurance levels for complex devices.

Why Other Options Are Wrong:

• Bacteria / Spores / Fungi alone: Incomplete; EtO covers all listed groups under proper conditions.
• Viruses only: Too narrow and incorrect.

Common Pitfalls:
Ignoring the need for proper aeration; residual EtO is hazardous and must be removed before device use.

Final Answer:
EtO sterilization acts against all of these microbial classes when properly validated.