Warning: This article contains spoilers for Grey's Anatomy Season 9, Episode 21: "Sleeping Monster." Click away now if you haven't seen the episode!

At the end of Grey's Anatomy Season 9, Episode 20: "She's Killing Me" Bailey (Chandra Wilson) was shocked to learn that she was the one common factor amongst three patients that got sick from a post-op staph infection. In Episode 21: "Sleeping Dragon," Jackson called in the CDC to investigate what happened, and to find out if Bailey was to blame.

So, was the heart of the hospital in the wrong?

Technically, no. While it turns out Bailey did have the staph infection in question, the CDC ruled that the real problem was faulty gloves. The hospital had switched brands under Pegasus' watch (because Pegasus is the root of all evil, duh), and the gloves had small tears that allowed Bailey's staph to infect her patients.

However, at the end of Episode 21 it was clear Bailey still blamed herself, and based on the preview for Episode 22, that holds true next week, too. How will she get over it and learn to stop blaming herself? We can't wait to find out.

Did you like the explanation of what happened? Sound off in the comments below.

Catch the episode of Grey’s Anatomy on Thursday, May 2, 2013, at 9 p.m. ET/PT on ABC.

Rebecca Martin is an editor at Wetpaint Entertainment. Follow her on Twitter @BeccaDMartin.