Which microorganism is commonly used to test steam autoclaves?

The correct choice, Geobacillus stearothermophilus, is commonly used to test steam autoclaves because it is a highly heat-resistant bacterium. This microorganism is a spore-forming bacterium that can survive the high temperatures and pressures typically found in autoclaving processes.

When conducting a spore test, the spores of Geobacillus stearothermophilus are placed in a biological indicator and subjected to the autoclave cycle. After the cycle is complete, the indicator is incubated to see if any spores survive. If the autoclave has functioned correctly, the spores will be killed, indicating that proper sterilization has been achieved.

The use of G. stearothermophilus is essential for validating that the autoclave is effective in sterilizing equipment and instruments, making it an industry standard for monitoring sterilization processes. Its specific resistance to heat makes it the ideal choice, as it ensures that the autoclave is functioning efficiently and safely.