Research leader Robert Munford points out that the mammalian immune system goes into a "tolerant" state during an infection, and its ability to fight off other invaders decreases.
The state persists even after the bacteria have been killed, he adds.
The researcher says that removing a molecule released by bacteria called lipopolysaccharide (LPS), which initiates tolerance, may help return the immune system to its normal state.
During the course of study, Munford and his colleagues injected the molecule into a group of mice that lacked an enzyme which destroys LPS, and a control group that retained the ability to make the enzyme.
Two weeks later, both groups of mice were given a deadly strain of bacteria.
Ninety per cent of the enzyme-deficient mice died, while most of the control mice survived, according to the researchers.
Munford says that that observation indicated that removing LPS restored the immune system to normal, reports New Scientist magazine.
He suspects that some people lack a similar enzyme, and that a drug to stimulate its production may prevent secondary infections.