The Scary World of Superbugs

For the world’s microbiologists, the biggest story of 2015 has already happened. Writing in the journal Nature, a group of scientists, including Kim Lewis at Northeastern University, have discovered a new class of antibiotic, which they are calling teixobactin.

Since the early days of penicillin, antibiotics have saved countless lives by treating bacterial infections. But alarmingly, bacteria have adapted, becoming increasingly resistant to even the most powerful antibiotics. That’s among the reasons why the discovery is so welcome.

But is teixobactin strong enough to fight today’s superbugs? To find out, Transmission sat down with infectious disease expert Barun Mathema, assistant professor of Epidemiology at Columbia University's Mailman School of Public Health.

Why do we need another antibiotic?

Medical advances have made it possible to keep sick people alive longer. The result is more procedures, and along with that you get more antibiotics.  Sick people tend to get more infections, so hospitals became the breeding ground for bacteria like MRSA (Methicillin-resistant Staphylococcus aureus) that are resistant to as many six antibiotics. Sometimes, antibiotics don’t work at all, so we’re essentially back to pre-antibiotic era.

Another problem is Big Pharma has been getting out of the anti-infective business. Antibiotics aren’t profitable like a Viagra or a Lipitor. They’d spend a billion dollars on developing a drug then lose it because drug resistance would develop. Teixobactin is being developed by a small biotech.

What are the scariest bugs?

There are many but I would highlight one in particular, CRE (carbapenem-resistant Enterobacteriaceae). There was an outbreak of CRE at the National Institutes of Health in 2011 that killed 12 patients. Patient zero came from New York City which is the epicenter of CRE. It’s typical for one of the larger hospitals here to get 15 cases a month, maybe more. Entire classes of antibiotics are not effective against superbugs like CRE.

What’s the picture in other parts of the world?

The more sophisticated your hospital system is, the bigger the problem. You see the most resistance in North America, Europe, and Japan. But now we’re seeing superbugs emerge in China and India. This is terrifying!

Another huge problem in the developing world is quality. I recall when I started my tuberculosis work in Nepal, we did everything we could educate patients to be compliant with their meds, which then came in these little blister packets. But when they opened the packs, instead of a pill, it was powder. In other cases, the active ingredient had become inert because it wasn’t stored properly initially.

Teixobactin to the rescue?

Not so fast! The world of microbes is divided into two classes: gram-positives and gram-negatives. Teixobactin only works against gram-positives, and the greatest need is for new antibiotics against gram-negative organisms like CRE. Had this compound been effective against multidrug resistant gram-negative bacteria, everybody in the infectious disease world would be popping champagne bottles.  

But this antibiotic is tougher than most, right? Drug resistance won’t develop as easily?

I wish they hadn’t put that in the paper. You’ve basically put a bull’s-eye on your back. It could be more difficult acquire resistance. But if I know anything about antibiotics and bacteria, there is almost always a way. Evolutionary selection is powerful; nature is very resourceful.

Is there any cause for celebration?

This compound is extremely promising. Teixobactin has only been tested in mice so far, but it was tolerated at very high concentrations in mammalian cells. But what’s really remarkable is the cultures method. That’s the paradigm shift.

Please explain.

Normally, a scientist takes a sample from the environment, dilutes it, and puts it on a plate at a certain temperature with nutrients and hopes something grows. But most microbes do not grow in artificial environments. We don’t know what many organisms need to survive. 

Kim Lewis does something different. He takes a sample from soil, dilutes it, and puts it into something called an i-chip, which is basically a well that can harbor a small number of bacteria. Then comes the secret ingredient. He puts the i-chip back the soil. The i-chip has a semi-permeable membrane where certain gasses and nutrients can get through. Suddenly the bug thinks, “I’m at home.” At this point, you can take them out of the i-chip and they grow in the lab. It’s an exciting development.