SEATTLE — Seattle Children’s reopened all of its 14 operating rooms Thursday that were closed in May after the hospital detected a fungus that had infected six patients since last year, leaving one dead.

But even while hospital officials said Wednesday they’re confident the operating rooms are free of Aspergillus mold spores after installing new air-handling equipment and stringently cleaning and testing, administrators didn’t say whether the hospital had notified families of patients potentially exposed to the toxic mold last year.

Dr. Mark Del Beccaro, Children’s chief medical officer, said Wednesday the risk now to patients is “incredibly low.”

“Seattle Children’s is both sorry that it happened and deeply concerned and want to make sure that whatever we do when we are ready to open we are thinking about patient safety,” he said.

The mold was found last year and again in May, which prompted the operating-room closures and forced hundreds of patients to delay or seek surgeries elsewhere.

The hospital recognized through recent testing that its air-handling system had been spreading the fungus, Del Beccaro said, something officials hadn’t recognized after three patients became infected in 2018, he said.

Del Beccaro didn’t answer some questions Wednesday about what and when hospital officials knew about the previous detection in spring 2018, which resulted in a patient’s death.

In May this year, after three other patients were found to be infected, Children’s notified about 3,000 patients who might have been exposed during the previous three months, Del Beccaro said.

When asked if the patients who had surgeries in spring 2018 were notified of the infections that year, Del Beccaro said he wasn’t sure and would have to check. He repeated several times no new cases would result from any potential exposure to Aspergillus last year.

Del Beccaro said the patient who died in 2019 was infected last year, but he declined to identify the patient, specify the type of surgery or say when exactly the death occurred.

“The children who we found in 2019 who had the infections belong to the same types of procedures that were very high risk,” said Del Beccaro.

Dr. Jeffrey Duchin, Public Health — Seattle & King County’s health officer, said he believes two of the cases were related to cardiac surgery, one was neurosurgery, two involved wound infections and another involved a deeper, more invasive tissue infection.

Children’s reported the patient’s death to the state Department of Health (DOH) on May 20 — the date the hospital also reported the mold was present in four of its operating rooms.