Strength in Numbers: Bacterial Clumping Mechanisms Promote Resilience and Drug Resistance
Recently, researchers at the University of Michigan (MI, USA) managed to build a device, the Taylor-Couette cell that closely simulates the dynamics of blood flow, its forces and turbulence. By adding a strain of Klebsiella pneumoniae bacteria that commonly causes bloodstream infections, they used the device to discover that bacteria infect the blood by literally sticking together.
The cell uses concentric cylinders to create eddies in the liquid growth medium, mimicking those of the blood. The results that were published in the Journal of Infectious Diseases showed that in a matter of almost two hours, miniscule aggregates of 10 to 20 bacteria formed in the flowing liquid. This is about the same amount of time required for infections to develop in human patients.
The research also managed to show that for the clumping to occur, the bacteria required certain sticky carbohydrate molecules (glycans) to be present on their surfaces. Moreover, the finding that these aggregates persisted even when a combination of ceftriaxone and ciprofloxacin was added, suggested that clumping is a means that floating bacteria use as protection against the effects of drugs.
John Younger, senior author of this research has been leading a team of physicians, engineers and mathematicians that studies why bacteria can survive and thrive despite the forces they endure in the blood. Using methods to simulate bloodstream conditions they’ve tested the mathematical models of the bloodstream’s fluid dynamics they created.
Dr. Younger said that this research demonstrates that if pathogenic bacteria are allowed to grow in fluid dynamic environments similar to that of the bloodstream, they start to depict features that manifest in patients.
Cuts and injuries, or even vigorous tooth brushing can lead to bloodstream infections. Intravenous lines or central line catheters used as part of patient treatment can pave the way to some others. The general majority has enough natural immunity to ward off such infections but rampant infections can develop in dialysis and cancer patients, those who’ve been severely injured or undergone surgery and elderly people.
Health professionals across the globe work hard to prevent and treat such infections. Yet hundreds of thousands of people a year die of sepsis after bacteria get into their blood and an exaggerated inflammatory response to the bloodstream infection triggers organ damage and failure.
This new research may help explain the ‘why and how’ of such infections and also why some of them resist treatment with even the most powerful antibiotics. This can open the gates to new ideas in intervention and treatment of such infections and hence enable the provision of better healthcare to the masses.
Source: J Infect Dis. (2012) 206 (4): 588-595. Read more at: http://jid.oxfordjournals.org/content/206/4/588
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