A strain of E. coli resistant to last-resort antibiotics has been identified on United States soil for the first time. Health officials say this could be “the end of the road for antibiotics,” leaving us virtually helpless in fighting future infections.

Last month, researchers identified a 49-year-old Pennsylvania woman as the carrier for a strain of E. coli resistant to the antibiotic Colistin. The woman visited a clinic in Pennsylvania, which forwarded a sample to Walter Reed National Military Medical Center. Walter Reed found the bacteria in her urine.

Think of this drug as our nuclear option — it’s employed for particularly dangerous pathogens, when every other drug fails. This includes the CRE family, a group of germs so resilient and deadly that health officials have dubbed it “nightmare bacteria”. Infection with these superbugs ends up killing up to 50 percent of patients in some instances, and the CDC lists them among the country’s most urgent public health threats.

Finding a bug that can shrug off even Colistin on home soil “heralds the emergence of a truly pan-drug resistant bacteria,” say the authors of the paper detailing the discovery.

“It basically shows us that the end of the road isn’t very far away for antibiotics — that we may be in a situation where we have patients in our intensive-care units, or patients getting urinary tract infections for which we do not have antibiotics,” CDC Director Tom Frieden said in an interview Thursday.

This is the first known carrier of a Colistin-resistant strain in the United States. Last November, a report by Chinese and British researchers who found the Colistin-proof strain in pigs, raw pork meat and several people in China was met with shock by public health officials worldwide. The deadly strain was later discovered in Europe and elsewhere.

Escherichia coli (E. coli) naturally occurs in your gut and most strains are harmless. Some, however, can cause food-borne diseases with fever, nausea and vomiting to bloody diarrhea. The infections are transmitted by eating or drinking contaminated food and water. E. coli resistance for a spectrum of drugs has been increasingly reported in cases of urinary tract infections, and the WHO warns that the most widely used oral treatment — fluoroquinolones — are rapidly becoming ineffective. Seeing strains develop virtual immunity to any of our antibiotics is very bad news, Frieden says.

“I’ve been there for TB patients. I’ve cared for patients for whom there are no drugs left. It is a feeling of such horror and helplessness,” he added. “This is not where we need to be.”

The CDC and the Pennsylvania State Health Department mobilized immediately to investigate the case and to trace the patient’s contacts to see if the bacteria had spread. The CDC also said it is looking for other potential cases in the healthcare facility the patient visited.

The full paper, titled “Colistin resistance in the USA” has been published online in the journal Antimicrobial Agents and Chemotherapy and can be read here.