I left a memo for another employee, who is from an agency, to clean up our work station. (This is only the second memo I have ever written her asking for her to clean up.) When I returned back to work, I found she had written me a note back. She began by accusing me of "harassment and slander of her person" and "unnecessary nitpicking". (Make note, in our field of work, cleanliness is a necessary step in keeping our patients bacteria- free.) Plus, on top of all that, she threatened to "call a mediation with our supervisors". Honestly, all I had wrote was a few examples that I noticed that were left soiled. I have never seen or spoken to her. I believe she has turned around and now is slandering and threatening me with her note. Could you please explain to me how was in wrong with my memo and advice on how to deal with this "dirty" employee?