Chapter 24, Problem 2CT

In the use-dilution test, a chemical is evaluated by its ability to kill ${10}^6$ to ${10}^8$ dried Clostridium sporogenes or Bacillus subtilis endospores. Why is this considered a stringent test?

Summary Introduction

To write:

The consideration of the use-dilation test as a stringent test.

Introduction:

Chemicals do not readily penetrate bacterial endospores, and the number of endospores used is higher than expected in a normal use of a disinfectant. When gram positive bacteria are in endospore state, they are resistant to disinfection and there is a limited number of agents that can destroy endospores and not the medical devices.

Explanation of Solution

In the use-dilution test, a chemical is evaluated by its ability to kill 10⁶to 10⁸ dried Clostridium sporogenes or Bacillus subtilis endospores. Bacterial endospores are highly resistant to hostile physical and chemical conditions. Only a few genera like Bacillus subtilis or Clostridium sporogenes are capable of forming endospores. These are the dormant forms of bacteria that allow it to survive the sub-optimal environmental conditions.

The spores are highly resistant to heat, radiation, disinfection and dessication. They are difficult to eliminate from the medical pharmaceutical materials and frequent cause of contamination as well. These different and difficult conditions along with the highly active chemicals to use for killing them and cause damage to the instrument makes it get considered as a stringent test. Chemicals do not readily penetrate bacterial endospores and the number of endospores used is higher than would be expected in the normal use of a disinfectant.

Conclusion

Thus, the conditions with the highly active chemicals to use for killing them and cause damage to the instrument makes it get considered as a stringent test.