What unit is used to express microbial contamination in dialysate?

• A. CFU/L
• B. CFU/mL
• C. CFU/dL
• D. CFU/m3

Answer: (B)

Concentration of viable microbes in dialysate is expressed as colony-forming units per milliliter because dialysate is a fluid encountered in very small volumes during treatment, and testing focuses on how many viable organisms are present in each milliliter. CFU represents viable bacteria counted on culture plates, so reporting per milliliter provides a precise, clinically meaningful measure of contamination for this application. Using CFU per liter, per deciliter, or per cubic meter would be less practical or relevant for the small-volume context of dialysate testing. Therefore, CFU/mL is the standard unit.