Which cleaning agent is ineffective against spore-producing bacteria?

• A. Alcohol
• B. Ethylene oxide
• C. Glutaraldehyde
• D. Peracetic acid

Answer: (A)

The main idea here is sporicidal activity. Bacterial spores have tough coats and low water content that protect their internal enzymes from many chemicals, so not all disinfectants kill them. Alcohol rapidly denatures proteins and disrupts membranes, which works well for many bacteria and viruses but does not effectively inactivate spores under typical use conditions. In contrast, agents like ethylene oxide are sterilants that penetrate spores; glutaraldehyde can achieve sporicidal activity with sufficient contact time and proper concentration, and peracetic acid is a strong sporicidal oxidizer used for sterilization. Because alcohol lacks reliable sporicidal action, it is ineffective against spore-forming bacteria.