SEATTLE — Seattle Children’s has closed three of its operating rooms because of the same fungus that forced the shutdown of all the hospital’s operating rooms earlier this year. The hospital is also looking into two new infections caused by the Aspergillus mold.

The mold was discovered during a routine air test conducted Sunday, according to a Children’s news release Monday, which said, “We are deeply sorry for the impact the air quality issues in our operating rooms continue to have on our patients and families. Seattle Children’s remains committed to doing what’s right to keep our patients safe.”

Children’s closed four operating rooms May 18 and shuttered the remaining 10 on May 24 because of Aspergillus. The rooms were reopened July 4.

The hospital struggled with the fungus last year, when three surgical patients became ill from the mold and one of them died. Three more patients became sick after being infected by the mold earlier this year. The patient who died was infected in 2018 but died this year. Children’s reported the 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.

Children’s officials did not immediately respond Monday to a series of questions and the hospital’s chief medical officer, Dr. Mark Del Baccaro wasn’t made available for an interview.

Aspergillus is a common mold found outdoors and indoors. People breathe in spores daily without getting sick, according to the Centers for Disease Control and Prevention. But people with lung disease or weakened immune systems, and especially organ or stem-cell-transplant patients, are at higher risk of developing aspergillosis, a disease caused by the mold. Aspergillosis can range from mild to serious, manifesting as an allergic reaction or infections in the lungs and other organs.

Patients are typically infected when dust is stirred up during renovation or construction at a hospital, or through contaminated biomedical devices.

DOH was notified of the situation Sunday night and is still learning the details, said spokeswoman Julie Graham. Children’s also informed Public Health — Seattle & King County Sunday night and told the agency it is initiating an investigation to determine the cause of the mold’s reappearance, said Public Health spokesman James Apa.

After the past two discoveries of Aspergillus, DOH opened investigations. In May, DOH and the Centers for Medicare and Medicaid Services (CMS) found the hospital to be deficient of effective oversight for “quality improvement, infection control that put patients at risk of harm from pathogenic organisms.” A surprise DOH inspection of Children’s this summer found it to be in compliance with state requirements.

CMS had threatened to remove Children’s from the federal program for patients using Medicare and Medicaid, but notified the hospital in August the upgrades it made to its air-filtration system moved Children’s back in compliance.

Death from a fungal infection caused by Aspergillus is not a “notifiable condition” that requires health-care providers to notify public-health authorities, according to DOH.

In an August interview hospital officials said the problem was caused by a gap in the array of small air filters used to catch smaller particles like mold. That air-handling unit was shut and a new one was to be installed, Del Beccaro said.

Children’s officials have not said how the mold returned. The Aspergillus problem last year was the result of small gaps in the walls of two operating rooms, Del Beccaro said.

The operating-room closures this year forced about 1,000 patients to postpone procedures or seek surgeries elsewhere.