A potentially deadly staph infection is spreading through Folsom Prison, which houses more than 4,000 inmates.

Methicillin-Resistant Staphylococcus Aureus, or MRSA, is a staph infection that is highly contagious and often resistant to medication.

More than 12 correctional officers have allegedly tested positive for the infection. The union said it suspects 40 to 60 inmates, and possibly more, are infected with MRSA as well.