Ear cartilage is more prone to a nasty infection than the earlobe during jewelry piercing, and can cause a disfiguring collapse of the ear as the cartilage dissolves, researchers said on Tuesday. An investigation into a two-month outbreak at a jewelry stand in an Oregon shopping mall found bacteria living in sinks that infected the ears of as many as 25 customers. Inexperienced employees spread the bacteria, Pseudomonas aeruginosa, to a spray bottle that was supposed to hold disinfectant and contaminated the piercing equipment, said a report published in the Journal of the American Medical Association.