Definition: This calculator computes the log reduction and percentage reduction of microorganisms, typically used to evaluate the efficacy of disinfectants or sterilization processes.
Purpose: It is used in microbiology to quantify the effectiveness of a treatment in reducing microbial populations, such as bacteria or viruses, which is critical for infection control and public health.
The calculator uses the following formulas:
Where:
Steps:
Calculating log reduction is crucial for:
Example 1: Calculate the log reduction and percentage reduction for a disinfectant that reduces a bacterial population from 1 × 10⁶ CFU to 1 × 10³ CFU:
Example 2: Calculate the log reduction and percentage reduction for a sterilization process that reduces a microbial population from 4.02 × 10⁶ CFU/mL to 1 × 10¹ CFU/mL:
Q: What does a 5-log reduction mean?
A: A 5-log reduction means a 99.999% decrease in microorganisms, reducing the population to 0.001% of its initial count [Ref web ID: 1].
Q: Why use log reduction instead of percentage?
A: Log reduction simplifies large reductions into manageable numbers. For example, a 6-log reduction (99.9999%) is easier to interpret than a percentage with many decimal places, especially in microbiology [Ref web ID: 4].
Q: Can this calculator be used for water treatment?
A: Yes, it can evaluate microbial reduction in water treatment processes, such as ensuring a 4-log reduction of viruses as required by some groundwater regulations [Ref web ID: 17].