One of the deadliest superbugs that is causing infection around the world is a bacterium called Pseudomonas aeruginosa. The bacterium, which is resistant to a range of existing antibiotics, causes infections of the blood and pneumonia and is especially dangerous to people with weakened immune systems like patients in hospitals. The World Health Organisation has classified Pseudomonas aeruginosa as having the highest level of threat to human health. But researchers in Australia have now identified structures that make that pathogen virulent, opening doors to developing drugs that can fight it.

Researchers at Monash University’s Biomedicine Discovery Institute have figured out the mechanism by which the bacteria secretes toxins that infect the host environment. In a paper published the online journal mBio, the researchers team showed that a protein nanomachine on the surface of bacterial cells is responsible for toxin secretion. This nanomachine called the Type II secretion system pumps out Exotoxin A, which is the bacteria’s most virulent weapon.

The researchers established the structure of the protein nanomachine by using electron microscopy to visualise pores on the cell surface. They generated tens of thousands of images created by the microscope’s beam to reconstruct a 3D map of the pore.

The researchers say that this visualisation of the nanomachine structure, medical researchers can develop drugs that might plug the machinery and prevent the secretion of Exotoxin A. The methodology used to determine is bacterial structure may also be used to investigate other bacteria surface nanomachines.