The company, Corizon Inc., received a $372 million, three-year contract last year after the previous contractor had a similar incident, the Arizona Republic in Phoenix reported Wednesday.
Clarisse Tsang, the hepatitis prevention coordinator for the Department of Health Services, said the inmates, all housed at a prison in Buckeye, were exposed because of "improper use of an insulin injection from a vial."
Corizon released a statement Wednesday saying the inmates were exposed to "blood-borne pathogens" caused by improper injection procedures. Spokeswoman Susan Morgenstern would not say if the prisoners were exposed to hepatitis or HIV. She also declined to say why the company waited three days to notify the public.
Corizon's statement said company officials met with the inmates Tuesday to counsel them and provide "appropriate preventative medications as a precautionary measure."
Corizon said it notified state corrections and health services officials of the situation Monday.