The Centers for Disease Control and Prevention detected more than 220 cases last year of a rare breed of “nightmare bacteria” that are virtually untreatable and capable of spreading genes that make them impervious to most antibiotics, according to a report released Tuesday.

Although the CDC has warned of the danger of antibiotic-resistant bacteria for years, the new report helps illustrate the scope of the problem. Anne Schuchat, the CDC’s principal deputy director, said she was surprised by the extent of the spread.

“As fast as we have run to slow (antibiotic) resistance, some germs have outpaced us,” Schuchat said. “We need to do more and we need to do it faster and earlier.”