The UCLA Health System, which includes the Ronald Reagan-UCLA Medical Center, has reported over 100 patients had been exposed to a drug-resistant bacteria.

Two of the seven patients confirmed to be infected have died, and the hospital is working with health officials to halt further infections.

In a statement released on Thursday, the UCLA Health System said it had notified over 100 patients who may have been exposed to carbapenem-resistant Enterobacteriaceae (CRE) during endoscopic procedures between October 2014 and January 2015.

The hospital explained it had followed manufacturer's instructions on how to sterilize the scopes; however, CRE was later detected, and an internal investigation found two scopes used to diagnose and treat pancreaticobiliary diseases were infected and "may have been a contributing factor in the death of two patients." The UCLA Health System said it has removed the two scopes and intensified its decontamination procedures, going "above and beyond manufacturer and national standards."

The Los Angeles Times reports the hospital notified 179 patients who may have been infected. Their report explained duodenoscopes are favored for being minimally invasive and helping detect and treat certain conditions early. Still, according to experts, some scopes can "be difficult to disinfect through conventional cleaning because of their design, so bacteria are transmitted from patient to patient," the Los Angeles Times said.

"These outbreaks at UCLA and other hospitals could collectively be the most significant instance of disease transmission ever linked to a contaminated reusable medical instrument," Lawrence Muscarella, a hospital-safety consultant and expert on endoscopes, said.

The hospital will provide free testing kits to patients at risk and has notified both Los Angeles County Department of Health Services and the California Department of Public Health, its statement explained.

According to the U.S. Centers for Disease Control and Prenvetion, CRE is most common in hospitals, nursing homes or other health care facilities, as the antibiotic-resistant germ usually affects patients who use ventilators, urinary bladders, or other devices, which go into the body. Patients taking many antibiotics are also at risk. Infections are difficult to treat, and the CDC cites a report that states up to 50 percent of infected can die.

Last month, a Seattle hospital reported 32 patients had been infected by contaminated endoscopes between 2012 and 2014 with bacteria strain of CRE. Eleven died.