Final answer:
The infection for which an alcohol-based hand rub is contraindicated is Clostridium difficile, due to its spore-forming ability and resistance to alcohol-based solutions.
Step-by-step explanation:
The student asks which infection contraindicates the use of an alcohol-based hand rub. The correct answer is b) Clostridium difficile (C. difficile). Alcohol-based hand sanitizers are generally not effective against spore-forming bacteria like C. difficile. This organism is notorious for causing hospital acquired infections and is often associated with outbreaks in healthcare settings. Its spore-forming ability allows it to survive for long periods on surfaces, making hand-washing with soap and water a preferred method for preventing its transmission.