Final answer:
Pseudomonas aeruginosa is the rod-shaped microorganism that caused the infection epidemic in whirlpool foot spas. It is an opportunistic pathogen that thrives in hot tubs and swimming pools.
Step-by-step explanation:
The rod-shaped microorganism that created an infection epidemic in whirlpool foot spas is Pseudomonas aeruginosa. This bacterium is an opportunistic pathogen that thrives in hot tubs and swimming pools, especially when the water is not sufficiently chlorinated. It can cause a skin infection known as “hot tub rash.”