Whyevery year hundreds of thousands of people fall ill and die from infections of resistant bacteriato antibiotics? According to an article you just published in the magazineJournal of Infectious Diseases, a team of researchers from the University of Michigan (USA) has shown that microbes can formantibiotic resistant lumpsin a very short time, even in a constantly flowing liquid like blood.
In their investigations they found thatit takes two hours for the microbes to form accumulations or clumps of ten to twenty bacteria, about the same time that human patients take to develop infections. The researchers also showed that these clumps form only when certain sticky carbohydrate molecules are present on the surface of microorganisms. The clumps persisted when two different types of antibiotics were added, indicating that by staying together the bacteria protect themselves from the drugs.
When the researchers injected the clumps into mice, the accumulations of bacteria remained intact even after completing many crossings of the bloodstream. Thelumps, about the size of a red blood cellThey even survived the leak, which normally occurs in the smallest blood vessels and which defends the body against invaders.
Over the past decade, these researchers have created advanced mathematical models of fluid dynamics in the bloodstream and the conditions necessary for promoting the growth of bacteria. Specifically, the bioreactor used to obtain the most recent results is called a Taylor-Couette cell and uses concentric cylinders, one of which is powered by a motor. The researchers added a liquid growth medium to the reactor and carefully controlled the rotation to produce eddies in the liquid that are similar to those in blood. Then they added bacteriaKlebsiella pneumoniaeone of the most common sources of bloodstream infection. The scientists tested two antibiotics that doctors often prescribe against sepsis: ceftriaxone and ciprofloxacin. Neither was effective in killing clumpy bacteria.
