Assistant Laboratory Animal Technician (ALAT) Practice Exam

Which sterilization method would usually provide the highest level of microorganism elimination?

1. Dry heat

2. Ethylene oxide exposure

3. Chemical sanitizers

4. Boiling

The correct answer is: Ethylene oxide exposure

Ethylene oxide exposure is recognized for its ability to achieve high levels of microorganism elimination, making it an effective sterilization method in laboratory settings. This gas is particularly useful for items that cannot withstand high temperatures or moisture, such as certain plastics, electronics, and complex instruments. Ethylene oxide works by penetrating materials and altering the DNA of microorganisms, leading to their inactivation. When compared to other methods, ethylene oxide is often favored for its effectiveness against a wide range of microorganisms, including bacteria, viruses, and fungi. This capability ensures a broader spectrum of sterilization, making it ideal for ensuring that instruments and materials are free from viable pathogens. Other methods mentioned have their own advantages but may not achieve the same level of sterilization. Dry heat, for example, is effective but typically requires longer exposure times and higher temperatures, which may not be suitable for all materials. Chemical sanitizers can reduce microbial loads but are generally considered less reliable for complete sterilization, as they often do not affect all types of spores. Boiling is effective for many bacteria but may not eliminate all pathogens, particularly spores and certain microorganisms resistant to heat. Thus, ethylene oxide exposure stands out as the method providing a superior level of microorganism elimination in many laboratory