A. baumannii bacteria is a nasty antibiotic-resistant bug that thrives in hospitals, where it takes advantage of weakened immune systems. Researchers have now found the bacteria's secret weapon and have ideas on how to use it for good.
Acinetobacter baumannii (A. baumannii) is what's known as an opportunistic bacteria because it infects people who are already suffering from illnesses such as pneumonia, urinary tract infections, or wounds. It can settle into the lungs, or cause wound infections in the body's organs or on its skin. It can survive on dry surfaces for up to a month and is often found on the skin of healthcare workers, which makes it highly transmissible. The bugs are also hard to kill with traditional methods. A. baumannii is such a menace that the World Health Organization has listed it as a top-priority critical bacteria.
In an attempt to figure out a way to fight the germs, researchers at Monash University realized that one of the things that must allow A. baumannii to thrive is that it can outcompete other bacteria in its environment. Focussing on that, the team discovered that the bacteria wipes out the competition by using a needle-like nano "machine" that injects deadly toxins into nearby bacteria.
"We learned how this toxin, called Tse15, is attached to the needle and then delivered into other bacteria to kill them," said study co-first author Brooke Hayes. "We showed that the toxin is stored in a protective cage-like structure inside A. baumannii, preventing it from harming the bacterium itself. When ready to attack other bacteria, the toxin must be released from the cage.
"This happens through a series of interactions between the toxin, the exterior of the cage, and the T6SS needle. Once the needle injects the toxin into a competitor, the toxin activates and kills the other bacterium, allowing A. baumannii to take over that surface."
Now that the researchers have deciphered the weapons employed by A. baumannii, they feel they could unravel ways to fight the bugs and possibly also recruit them to do good. While learning how to disable its weapon system could open pathways to killing it more efficiently, the researchers say they may also be able to find a way to engineer versions of the germ that inject different toxins into nearby bacteria, enlisting them in the fight to kill other harmful invaders.
Such a breakthrough would join other methods being developed to combat so-called superbugs including using a molecular wedge that opens them up to destruction by antibiotics, using mechanical methods of destruction that prevent the germs from evolving, and using a one-two punch to overwhelm disease-causing bacteria and crush their chance of defending themselves.
The research has been published in the journal Nature Communications.
Source: Monash University