Which of the following is required for good quality assurance in bacteriology?

• A. toxic residue test on glassware
• B. suitability test on water used for media
• C. discard opened dehydrated media after 6 months
• D. incubate refrigerated media before use

Answer: (B)

Ensuring reliable bacteriological results starts with the inputs used to make media, especially the water. Water quality can contain substances that inhibit or alter growth, or change the media’s pH and mineral balance, which would skew test outcomes. A suitability test on water used for media checks that the water supports expected growth conditions and does not introduce interfering contaminants. This makes it the most important QA step for media performance. Other practices mentioned—testing glassware for toxic residues, discarding opened dehydrated media after a fixed period, or incubating refrigerated media before use—are not standard QA requirements for ensuring media will perform correctly in routine bacteriology work.