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Outsmarting Bacteria


Sebastian Kaulitzki/Hemera/Thinkstock
Sebastian Kaulitzki/Hemera/Thinkstock

Humans have spent the past century trying to outfight bacteria. What if we could outsmart them instead?

Smiting your average bacterium has been easy enough since the discovery of penicillin's antibacterial properties in 1928. Created as a byproduct by Penicillium fungi, penicillin prevents a bacterium from replenishing its own cell walls - eventually causing the cell to burst and die. Antibiotics derived from other substances may prevent the cell from multiplying or interfere with its formation of other subcellular structures. But bacteria can defend themselves - for example, by growing sturdier cell walls. The ones with particular talent for doing so survive to multiply, creating generations of antibiotic-resistant germs.

Resistance is an increasing concern. The CDC estimates that each year, more than 23,000 people die as a direct result of infection by resistant bacteria in the U.S. alone. Many other deaths occur due to conditions complicated by such infections. Professor Jeremy Ferrar, Director of the Oxford University Clinical Research Unit in Vietnam, spoke to BBC Radio 4's "Today" about the issue just last week:

"What we will see is people actually spending longer in hospital, patients getting sicker and having complications and dying, and it will creep up on us almost without us noticing. "This will not be the sort of contagion-like event of somebody landing from Hong Kong in London with a pneumonia that is emerging that we've all feared. This will creep up on us insidiously, and of course that's in many ways more difficult to cope with."

So sheer might is just building badder bacteria. What about smarts?

Traditionally, we haven't considered bacteria to have intelligence worth outsmarting. After all, they're literally brainless single-celled organisms. We've discussed previously that bacteria can be used to solve math problems faster than people and even conventional computers, but that works by observing the expression of modified genes - the bacteria are just running genetic programs, not actually working together to solve the problems.

But it's not unusual for such simple critters to collaborate. Some single-celled amoebae called slime "molds" can learn mazes, share resources throughout a colony and relocate the colony when food grows scarce. Our compatriots at Stuff to Blow Your Mind did a great episode on all that: The Memory of Slime.

And, OK, amoebae are more complex than bacteria - bacteria don't even have a cell nucleus. But ongoing research indicates that bacteria can communicate with one another by producing, releasing and detecting signal molecules. It's called quorum sensing, and it lets bacteria synchronize gene expression for better survival - and not just bacteria within the same species. This process may be allowing even different kinds of bacteria to work together, producing protective biofilms (i.e., highly resistant surface colonies), becoming more or less virulent and toggling dormancy. (Side note: I'm really curious whether research into quorum sensing could improve bacterial computing.)

However, just as signal jamming has been used by governments and militaries to prevent unwanted communication, scientists are working on ways of jamming those bacterial signals. They're calling it quorum-sensing inhibition. Several approaches are in development, using various chemicals and enzymes that disrupt the production or reception of signal molecules. By preventing communication - or by sending out false signals - they're hoping to fool bacteria into a non-pathogenic (i.e., unharmful) state.

Could this be a replacement for traditional antibiotics? The research is still in vitro - in lab dishes. We'll need lots of testing to determine the best methods of disrupting bacterial communication and ensure that they're safe for living hosts. But the potential is huge. Imagine a future with no bacterial pneumonia or meningitis, no typhus, anthrax, Lyme disease, botulism, gonorrhea, tuberculosis ... We don't worry too much about most of these among healthy populations in developed countries because of our aggressive use of antibiotics. But as bacteria evolve, we must evolve, too.