Bacteria that switch antibiotic resistance on and off are going undetected. Microbiologist Karin Hjort is on a mission to find out how they do it.

Microbiologist Karin Hjort sitting in a lab with stacks of petri dishes.

For decades, scientists have been puzzled by a mysterious type of antibiotic resistance. Called "heteroresistance," it occurs when a tiny fraction of bacteria in a population can evade antibiotics, and it is almost impossible to detect with routine clinical tests. Yet some scientists think heteroresistance could be the culprit behind many antibiotic treatment failures.

Karin Hjort, a microbiologist at Uppsala University in Sweden, is a leading expert on heteroresistance. Live Science spoke with Hjort about what heteroresistance is and what implications it has for the fight against superbugs.