Patients who suffered infections after undergoing surgery at a Denver hospital are suing over its sterilization practices.

The lawsuit filed Saurday by 67 patients and 20 spouses alleges that Porter Adventist Hospital’s failure to properly clean its equipment caused “hundreds of infections” as far back as 2015 and at least one death.

Last April, the hospital revealed it had had problems with cleaning its instruments. It temporarily shut down its operating room but downplayed the risk of infections.

The Denver Post reports that a state investigation found that the hospital knew more surgical patients were developing infections by early 2017. However, the state’s chief medical officer Tista Ghosh said the state never conclusively linked infections to the sterilization problems.

The hospital said Monday it will address the allegations in court and that it meets the state’s sterilizations guidelines.