She stepped on something, injured her skin, and it got infected. Might have happened even without trying on shoes.
I agree. Trying on the shoes was only coincidental to her having the infection, IMHO.
No way this happened without a break in the skin on her feet. Then the most likely source of the infection is whatever caused the break in the skin not shoes she tried on. She was more likely to contaminate the shoes with an open sore on her foot than get contaminated by them. But that doesn’t make scary headlines.....