(Evolution in Real Time) Microbes slowed by one drug can rapidly develop resistance to another

Infectious bacteria that are down but not quite dead yet may be more dangerous than previously thought. Even as one antibiotic causes the bacteria to go dormant, the microbes may more easily develop resistance to another drug, according to new research.

Deadly Staphylococcus aureus bacteria that could tolerate one type of antibiotic developed resistance to a second antibiotic nearly three times faster than fully susceptible bacteria did, researchers report in the Jan. 10 Science. The findings could suggest why drug cocktails used to knock out infections quickly sometimes fail, and may eventually lead to changes in the way antibiotics are prescribed in certain situations.

“Tolerance is not as well-known or as well-publicized [as resistance], but [this] work shows it is extremely important,” says Allison Lopatkin, a computational biologist at Barnard College in New York City, who was not involved in the study. “It is very much happening, and we need to pay closer attention to it.”

Antibiotic-tolerant bacteria stop growing in the presence of antibiotics, entering a sort of dormant state that helps the microbes weather the drugs’ assault for longer than usual. “They’re just putting their heads down,” says Nathalie Balaban, a biophysicist at the Hebrew University of Jerusalem. Tolerant microbes aren’t capable of overcoming or counteracting antibiotics in the way that resistant organisms do. The microbes eventually die if exposure to the antibiotic continues at a killing dose, and if resistance doesn’t pop up.

https://www.sciencenews.org/article/microbes-slowed-one-drug-can-rapidly-develop-resistance-another


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Evidence of evolution is abundant. Farmers have to keep switching pesticides, because the next year's pests are the survivors of this year's pesticides (which is how species evolve immunity).

Staph infections are an even better example. No living population can be completely eradicated by the same infection or poison.