Which growth medium may be used when sampling water and dialysate in dialysis?

• A. Blood agar
• B. MacConkey agar
• C. Anaerobic agar
• D. Chocolate agar

Answer: (A)

Sampling water and dialysate aims to detect a broad range of microorganisms that could affect patient safety. A nonselective, broad-supporting medium like blood agar provides a hospitable environment for many bacteria—Gram-positive cocci, Gram-negative rods, and some fastidious organisms—allowing recovery of a wide spectrum of potential contaminants from these aqueous systems. In contrast, MacConkey agar mainly targets Gram-negative enteric bacteria and may miss Gram-positive organisms; anaerobic agar favors anaerobes; chocolate agar is enriched for certain fastidious respiratory pathogens and won’t necessarily reveal the full range of environmental bacteria present in water or dialysate. Therefore, blood agar is the most suitable choice for broad recovery in these samples.