lyme disease bacterium

B. burgdorferi, lyme disease bacterium, is very difficult to isolate.


Even after decades of research, some things about Borrelia burgdorferi, the Lyme Disease bacterium, still evade scientific comprehension. For example, we still don’t really understand how it causes the bewildering array of symptoms that LD patients can present.

But we do know some basic information about the organism itself… and we’re learning more every day. So let’s take a quick look at this tiny invader.

Downward Spiral

Borrelia burgdorferi is a spirochete, a species of corkscrew-shaped bacteria similar to the organism that causes syphilis. It’s the cause of Lyme Disease infections not only in the United States, but also in Europe.

Humans almost always acquire B. burgdorferi infections from Ixodes tick bites; in North America, these include blacklegged and western blacklegged deer ticks. Dog ticks can transmit the disease to canines, though apparently not to humans, and there’s evidence that several other ticks species may also be vectors.

Hunting It Down

B. burgdorferi is very difficult to isolate. The presence of relatively few spirochetes can produce disease symptoms; so, often being so few in number, they’re hard to find directly. Worse, it’s hard to grow them outside the human body in blood cultures for diagnostic and study purposes.

Researchers didn’t even formally define LD until the 1970s, though it was known in the literature for more than a century prior. It wasn’t until 1982 that Swiss-American researcher Willy Burgdorfer isolated and identified B. burgdorferi as the causative agent. For that reason, the organism bears his name.

Why It’s Hard to Fight

Aside from bull’s-eye rashes, the only solid way to identify an LD infection is by detecting substances called antigens that the body creates to fight B. burgdorferi spirochetes. Unfortunately, those antigens aren’t common in the bloodstream until the infection is well established.

Even then, the antigens may bind themselves to the bacteria they’re fighting, leaving few free-floating antigens for the diagnostic tests to detect.

And, while it’s dangerous to ascribe intentions to single-cell organisms, B. burgdorferi seems unusually clever at hiding. Most of the bacteria soon withdraw from the bloodstream altogether into the cerebrospinal fluid, the brain, and other places where most blood-borne antibiotics can’t target them.

There’s increasing evidence that B. burgdorferi can also tunnel into cells and hide there. All these hidden pockets of infection provide reservoirs for the disease to re-infect an LD patient, even when prior treatment has wiped out the main infection in the bloodstream.

The Biofilm Complication

Recent research has added a new wrinkle to the issue: the likelihood that B. burgdorferi forms slimy colonies called “biofilms” that make the spirochetes even harder to kill. These cooperative groups are up to 1,000 times more resistant to antibiotics than individual cells.

Not only does the exterior layer of the biofilm protect the bacteria inside, the internal conditions (low pH and lack of oxygen) can either neutralize an antibiotic or render the bacteria inactive, so the antibiotics don’t affect them. Antibiotics can’t work if an organism isn’t growing and multiplying.

Hope for the Future

Researchers are gradually becoming aware of just how resourceful B. burgdorferi is, but this is no reason to despair. It actually bodes well for the evolution of treatment options, because if they truly comprehend how tough it is, they’ll be more willing to fight it harder. Plus, it suggests new lines of treatment.

The researchers are working hard for all of us. And though this may provide little comfort to LD sufferers now, it’s only a matter of time before the Lyme disease bacterium is as easily treatable as all the other scourges that medical science has defeated.

 

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