The news that researchers have found a person in the United States carrying bacteria resistant to antibiotics of last resort has caused alarm among public health and infectious disease experts.

The antibiotic-resistant strain was found in the urine of a 49-year-old Pennsylvania woman. The E. coli bacteria contained a gene that makes it resistant to the antibiotic colistin, the drug used against particularly dangerous types of superbugs that can already withstand other antibiotics. Over the long term, experts are very worried that colistin resistance, which can spread easily to other bacteria, could lead to superbugs that could cause untreatable infections.

In the short term, experts say there is no need to panic.

We spoke with Yohei Doi, an infectious disease doctor at the University of Pittsburgh, who has studied the problem, to answer some of the questions readers have asked about the discovery. His answers have been edited for clarity and length.


Q: How worried should people be about this strain of bacteria?

A: While certainly concerning and something to keep a close eye on from a public health point of view, there is no evidence that this is a widespread problem at this time. In addition, this particular E. coli strain is sensitive to several other more commonly used antibiotics such as carbapenems. Even in the rare event that you get sick from this bacteria, there are treatment options available.

Q: This strain has been found in pigs and raw pork. Can someone pick up this strain from food? Will cooking kill it?

A: The bacteria will be dead after cooking. Undercooked meat products may pose a risk for food poisoning in general, but the risk of meat products being contaminated with this type of resistant bacteria is probably quite small in the United States. Good hand hygiene in cooking should minimize any risk in any case.

Q: Should doctors and hospitals be doing anything differently now that we know this resistance gene has been found in the United States?

A: It's always prudent for doctors, when treating a bacterial infection with colistin, to make sure it works against the bacteria in a test tube when they need to give this antibiotic to their patients, instead of assuming that it should work. Many hospitals already do this, including ours.

Q: Should people with elective surgery postpone their operations?

A: There is no reason to postpone elective surgeries because of this finding. Infections following surgeries unfortunately happen on occasion, but they are usually caused by different types of bacteria, such as Staphylococcus aureus ("Staph") and not E. coli.

Q: How did this patient get this strain of bacteria in the first place?

A: That's the biggest question, where it came from. We can assume it came from outside the country. She may have come in contact with someone who recently traveled to countries where this is more common. And it's also possible she somehow ingested this. There have been other instances where one family member came down with an antibiotic-resistant infection and other family members are more likely than not to carry the same bacteria in their GI tract, with or without infection.

Or she may have had an underlying medical illness and been in a rehab facility or hospital and gotten it from someone in those places.

Q: How likely is it for someone to pick up this antibiotic-resistant strain of E. coli from food?

A: Even if you ingest some resistant E. coli, most of it would be dead as it goes through the stomach because the stomach is highly acidic and designed to sterilize what we ingest. Most of it is gone by the time it comes out of the stomach. Even if some of it makes it through, it can hang out in your gut for a while and disappear. Only a very small portion of those people may become sick.

So to summarise, you are starting at a very low risk in food, and then it goes through the stomach, and most will disappear in the digestive tract. I don't think there is anything to be super worried about.

Q: Should people be taking any special precautions?

A: Common sense prevails. Cook your meat. Wash your hands as you prepare food. These are two basics that we should be mindful of regardless of this piece of news.

Q: Why are you and other public health officials worried about this finding?

A: If this becomes more common and the gene gets into more bacteria that are already more resistant to other kinds of antibiotics, that's a concern. If it gets into the health-care system, like nursing homes, acute care hospitals, where people probably don't have good immunity or ability to fight infections, that's the long-term concern. Then you are more vulnerable and affected than the average healthy person.