Staphylococcus aureus Gradient Dilution Calculator

The Staphylococcus aureus Gradient Dilution Calculator is designed for microbiology labs and research professionals who need to prepare dilution series for quantitative analysis, such as antimicrobial susceptibility testing, colony-forming unit (CFU) enumeration, or minimum inhibitory concentration (MIC) assays.

Historical Background

Staphylococcus aureus, a major pathogen in clinical microbiology, requires precise quantification for studying its growth behavior and response to treatments. Serial dilution techniques, especially 10-fold dilutions, are standard in microbiological studies to assess bacterial load and test sensitivity to antibiotics.

Calculation Formula

\[ \text{Diluted Concentration}_n = \frac{\text{Initial Concentration}}{(\text{Dilution Factor})^n} \]

Where:

• \( n \) = dilution step number (starting from 0)
• CFU/mL = colony-forming units per milliliter

Example Calculation

• Initial: \( 1 \times 10^8 \) CFU/mL
• Dilution Factor: 10
• Steps: 4

Results:

• Step 0: \( 1.00 \times 10^8 \) CFU/mL
• Step 1: \( 1.00 \times 10^7 \) CFU/mL
• Step 2: \( 1.00 \times 10^6 \) CFU/mL
• Step 3: \( 1.00 \times 10^5 \) CFU/mL
• Step 4: \( 1.00 \times 10^4 \) CFU/mL

Importance and Usage Scenarios

• Microbiology Labs: CFU counts, plating assays, growth curve studies.
• Antibiotic Research: Determining MICs or bactericidal thresholds.
• Vaccine Development: Dosage control and immune response quantification.
• Educational Labs: Teaching dilution methods and quantitative microbiology.

Common FAQs

1. What is a typical dilution factor in microbiology?

   • Most commonly 10 (10-fold), but 2-fold and 5-fold are also used.

2. Why are serial dilutions important?

   • They allow precise estimation of bacterial concentrations within quantifiable ranges.

3. Can this calculator be used for other bacteria?

   • Yes, it’s applicable to any microbial culture where serial dilutions are needed.

This tool simplifies complex lab preparations and helps ensure accurate and reproducible microbiological testing.