In Pennsylvania, in April, a 49-year-old woman came into an clinic complaining of a urinary tract infection. But what was ailing her was much scarier than a basic UTI. Her urine samples contained E. coli that carried an antibiotic resistance to colistin, a drug that’s been used to kill bacteria that have developed resistance to many of the drugs used to defeat them.
This patient is not the first in the world to harbor bacteria resistant to colistin, but she is the first in the U.S. The resistance gene that these bacteria carry “heralds the emergence of truly pan-drug resistant bacteria,” write the authors of the report on the Pennsylvania case. It had previously be found in people in 20 countries, as well as in pigs.
Colistin has been effective in treating otherwise-resistant diseases because its harsh side effects kept doctors from prescribing it. It has been used more widely in agriculture, though. American researchers have been looking for this resistance since its existence was first announced in November.
The bacteria found in Pennsylvania are still vulnerable to some antibiotics. As reporter Maryn McKenna, who’s long covered superbugs, explains:
Bacteria acquire resistance genes like gamblers amassing a hand of cards, but the way the “cards” arrive is not step-wise—bad resistance, and then worse resistance, and then the worst—but randomly. What that means, in this case, is that the Pennsylvania E. coli possesses ESBL resistance (bad) and colistin resistance (worst)—but it remains susceptible to other intervening categories of drugs.
At some point, though, some lucky bacteria will collect enough resistance genes to make it invulnerable to the treatments we’ve developed.
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