Contaminated medical instruments are to blame for infecting seven patients — including two who died — with an antibiotic-resistant and potentially deadly “superbug” at Ronald Reagan UCLA Medical Center, hospital officials said. A total of 179 patients may be infected.

They were exposed to Carbapenem-Resistant Enterobacteriaceae, or CRE, during endoscopic procedures between October and January when it was discovered during tests on a patient, said Dale Tate, a University of California, Los Angeles spokeswoman.

The potentially infected patients are being sent free home-testing kits that UCLA will analyze, the university said.

The bacteria may have been a “contributing factor” in the deaths of two patients, a university statement said.

Similar outbreaks of CRE have been reported around the nation. They are difficult to treat because some varieties are resistant to most known antibiotics. By one estimate, CRE can contribute to death in up to half of seriously infected patients, according to the national Centers for Disease Control and Prevention.

The bacteria can cause infections of the bladder or lungs, leading to coughing, fever or chills.

UCLA said Wednesday that infections may have been transmitted through two endoscopes used during the diagnosis and treatment of pancreatic and bile-duct problems.

“We notified all patients who had this type of procedure, and we were using seven different scopes. Only two of them were found to be infected. In an abundance of caution, we notified everybody,” Tate said.

The two medical devices carried the bacteria even though they were sterilized according to the manufacturer’s specifications, UCLA said. “We removed the infected instruments, and we have heightened the sterilization process,” Tate said.

The CDC said that national figures on the bacteria are not kept, but 47 states have seen cases.

Since 2012, there have been about a half-dozen outbreaks reaching as many as 150 patients, according to the Los Angeles Times, which first reported the UCLA outbreak.

One outbreak occurred in Illinois in 2013. Dozens of patients were exposed to CRE, with some cases apparently linked to a tainted endoscope used at a hospital.

A Seattle hospital, Virginia Mason Medical Center, reported in January that CRE linked to an endoscope sickened at least 35 patients, and 11 died, although it was unclear whether the infection played a role in their deaths.

Experts say the cases represent a disturbing surge.

“This bacteria is emerging in the U.S. and it’s associated with a high mortality rate,” Dr. Alex Kallen, an epidemiologist in CDC’s Division of Healthcare Quality Promotion, told the LA Times. “We don’t want this circulating anywhere in the community.”