DALLAS — Updated at 6:55 p.m. with additional information. U.S. health officials say they now have evidence that an untreatable “superbug” fungus has spread in two hospitals in Collin County and a nursing home in Washington, D.C. There were four deaths related to the fungus at two health care facilities in Collin County, officials said Friday. Outbreaks of the Candida auris fungus were reported Thursday to the Center for Disease Control and Prevention. A handful of the patients had invasive fungal infections that were impervious to all three major classes of medications. The new cases did spread, the CDC concluded. In Washington, D.C., a cluster of 101 C. auris cases at a nursing home dedicated to very sick patients included three that were resistant to all three kinds of antifungal medications. A cluster of 22 in two hospitals in North Texas included two with that level of resistance. The facilities weren’t identified. The state health department told WFAA Friday that they occurred