A new study led by Laura Mike was published in Nature Communications

A new Pitt study published in Nature Communications uncovers how a common amino acid plays a pivotal role in regulating the mucoid phenotype of hypervirulent Klebsiella pneumoniae (hvKp), a highly infectious strain of bacteria responsible for severe community-acquired infections.

Led by Laura Mike, assistant professor in Pitt’s Department of Medicine, and Brooke Ryan, of the University of Toledo, have found that arginine, an amino acid abundant in certain human tissues, can control whether hvKp adopts a sticky, mucoid state — a key factor in the bacteria’s ability to evade immune defenses and cause serious illness.

HvKp has gained notoriety for causing life-threatening conditions, even in healthy individuals. A hallmark of these infections is the bacteria's mucoid phenotype, which makes colonies appear glossy and sticky due to changes in capsular polysaccharide (CPS) chain length. Until now, the environmental cues triggering this mucoidy were poorly understood.

“We are now considering whether simple dietary changes could reduce one’s risk of infection or improve infection treatments,” said senior author Laura Mike. “These findings open up the possibility of reducing bacterial virulence without relying on traditional antibiotics.”

Given the rising threat of antibiotic-resistant hvKp strains, understanding and interrupting its mucoidy regulation could provide a promising new therapeutic strategy. Instead of killing the bacteria outright, potentially leading to an increase in antibacterial resistance, therapies could instead focus on disrupting hvKp’s ability to become mucoid and thereby evade immune defenses, suggesting that the arginine-ArgR may become a critical target in developing next-generation treatments for hypervirulent bacterial infections.

Other Pitt authors on the study included Drew Stark, Grace Shepard, Emma Mills, Saroj Khadka, and Daria Van Tyne.