Selective antibiotics target specific bacteria to spare the microbiome

Selective antibiotics target s...
Researchers have developed antibiotics that target only specific strains of bacteria
Researchers have developed antibiotics that target only specific strains of bacteria
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Researchers have developed antibiotics that target only specific strains of bacteria
Researchers have developed antibiotics that target only specific strains of bacteria

Antibiotics are one of the most important medical marvels of the modern age, letting us easily treat infections that would have once been lethal. The problem is they aren't picky, blasting good and bad bacteria alike and messing up the delicate balance of the gut microbiome. But now researchers have developed a more targeted approach, with drugs that are able to zero in on specific species of bacteria.

Each of us is our own walking universe, teeming with trillions upon trillions of bacteria, viruses, fungi and archaea. But before you bust out the hand sanitizer, remember that many of them are actually good for us, helping with vital processes such as digestion and immune responses. In fact, disruptions to the gut microbiome may have effects on all sorts of health issues, such as diabetes, obesity, Alzheimer's, heart disease and cancer.

And few things are as disruptive to the microbiome as antibiotics. These drugs are designed to kill bacteria of course, but unfortunately they work like a shotgun blast, indiscriminately wiping out large populations of all kinds of bacteria in the gut. While the microbiome does recover somewhat, studies have shown that not all species return, and worse still, often the only ones that do survive are those that are resistant to the drugs. This is contributing to the rising tide of "superbugs" that threaten to make antibiotics ineffective entirely.

Developing antibiotics that can target specific strains of bacteria could help solve all of those problems. And two new studies, conducted by researchers at the University of Konstanz and Duke University, have managed to do just that.

The first kills off a bacteria called Moraxella catarrhalis, which is behind some middle ear and sinus infections, particularly in children. The drug's development began when the team noticed that a signaling compound given off by a different bacteria, Pseudomonas aeruginosa, seemed to single out M. catarrhalis.

The researchers went on to engineer their own synthetic version of the compound, and found it made for a new antibiotic class that was efficient and highly selective for M. catarrhalis. Even closely related species were spared.

While the team isn't entirely sure how the drug works, it's believed that it affects the bugs' metabolism, and P. aeruginosa probably uses the compound to reduce competition for resources.

In the second study, some of the same team members created a new antibiotic that targets the malaria parasite. Normally, the parasite bides its time in the liver for a while before it begins attacking blood cells. The new drug targets it during this crucial but vulnerable stage of its life cycle.

While these two developments are promising, the researchers are continuing to study the drugs. It's hoped that eventually selective antibiotics could be created for a range of different species, letting scientists pick off the bad bugs while leaving the good ones behind. Already, another team has developed a drug that singles out C. difficile.

The two studies were published in the journals Chemical Science (PDF) and Chemical Communications.

Source: University of Konstanz

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