Scientists have produced and tested, in mice, a vaccine that protects against a worrisome superbug: a hypervirulent form of the bacteria Klebsiella pneumoniae.
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And they've done so by genetically manipulating a harmless form of E. oli, report researchers at Washington University School of Medicine in St. Louis and VaxNewMo, a St. Louis-based startup.
Klebsiella pneumoniae causes a variety of infections including rare but life-threatening liver, respiratory tract, bloodstream and other infections.
Little is known about how exactly people become infected, and the bacteria are unusually adept at acquiring resistance to antibiotics.
The prototype vaccine, details of which are published online Aug. in Proceedings of the National Academy of Sciences, may offer a way to protect people against a lethal infection that is hard to prevent and treat.
Hypervirulent strains of Klebsiella caused tens of thousands of infections in China, Taiwan and South Korea last year, and the bacteria are spreading around the world.
About half of people infected with hypervirulent, drug-resistant Klebsiella die.
Two types in particular known as K1 and K2 are responsible for 70 percent of the cases.
Rosen; senior author Christian Harding, PhD, a co-founder of VaxNewMo; first author Mario Feldman, PhD, an associate professor of molecular microbiology at Washington University and a co-founder of VaxNewMo; and colleagues decided to create a vaccine against the two most common strains of hypervirulent Klebsiella.
The bacterium's outer surface is coated with sugars so the researchers designed a glycoconjugate vaccine composed of these sugars linked to a protein that helps make the vaccine more effective.
Similar vaccines have proven highly successful at protecting people against deadly diseases such as bacterial meningitis and a kind of pneumonia.
To test the vaccine, the researchers gave groups of 20 mice three doses of the vaccine or a placebo at two-week intervals.
Then they challenged the mice with about 50 bacteria of either the K1 or the K2 type.
Previous studies had shown that just 50 hypervirulent Klebsiella bacteria are enough to kill a mouse.
In contrast, it takes tens of millions of classical Klebsiella the kind that affects hospitalized people to be similarly lethal.
Of the mice that received the placebo, 80 percent infected with the K1 type and 30 percent infected with the K2 type died.
In contrast, of the vaccinated mice, 80 percent infected with K1 and all of those infected with K2 survived. ■