More than 1,800 patients treated by one nurse at a South Florida hospital may have been exposed to HIV and hepatitis.

Broward General Medical Center said Monday the nurse reused saline bags and tubing during cardiac stress tests involving the injection of fluids. The hospital has sent letters to all 1,851 people who may've been affected from January 2004 to early September.

Hospital officials say the risk of exposure is low, but all affected patients should be tested for HIV and hepatitis B and C.

The nurse, who has not been identified, resigned and was reported to the Board of Nursing.

The hospital discovered the problem after a patient noticed the nurse misusing the equipment and anonymously called in.