Employer drug tested me based on accusations of other employees. I passed and kept my job but now everyone thinks differently of me. Do I have a case for defamation?

Myself and two other employees were accused of being part of a drug ring by other employees on a different shift. The accusers have gotten two other people fired by using HR as an outlet to get rid of people they do not like. The company drug tested 2 of us and 1 of us quit on the spot. The 2 that took the drug test, myself and another, passed. We received apologies from management but feel like we are now viewed differently and have to watch our backs at work. The company did not provide us with written forms of our rights according to CSERA and the NCDOL before escorting us to a lab for testing. Do you think that we have a case for defamation and creating a hostile work environment?