How do you prevent cross-contamination in a microbiology lab handling multiple strains?

• A. Unidirectional workflow; separate benches; dedicated equipment; proper decontamination; color-coded PPE; restricted access.
• B. Random workflow; shared benches; common equipment; no cleaning.
• C. Work with all strains on same bench; reuse PPE.
• D. Use only one glove for all tasks.

Answer: (A)

Preventing cross-contamination hinges on controlling how materials and people move through the lab so that organisms don’t move between tasks or areas. The best approach uses a unidirectional flow that goes from clean to dirty, with each strain handled at its own separate bench and with dedicated equipment. This physical separation, combined with routine decontamination of surfaces and equipment, keeps any potential contamination from one task from spreading to another. Color-coded PPE helps ensure that gear used in one area isn’t accidentally worn in another, and restricted access limits who can enter the controlled zones, reducing risk of accidental transfer.

This combination directly interrupts the pathways through which contaminants could be moved: personnel, tools, and surfaces are all controlled to prevent mingling of strains. In contrast, a random workflow, shared benches and equipment, or working all strains on the same bench would create frequent opportunities for cross-contact; reusing PPE across tasks also risks carrying organisms from one area to another. Using only one glove for all tasks similarly fails to stop transfer between steps or areas.