The National Institutes of Health reported that researchers at Northeastern University have discovered a new antibiotic called teixobactin in soil from a grassy field in Maine. Teixobactin is unique because of its ability to kill a wide range of infection-causing bacteria through a mechanism markedly different from those of existing antibiotics.
Teixobactin is a defensive toxin made of a few amino acids in an unusual arrangement. It is produced by the newly identified proteobacteria species Eleftheria terrae. Test tube experiments showed teixobactin to have excellent activity against 19 types of gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and enterococci, which are now immune to most other antibiotics.1 Trials on mice showed that teixobactin rapidly cleared infections of drug-resistant strains of Mycobacterium tuberculosis and S aureus bacteria, according to a study in Nature.2
The compound reportedly attacks these and other gram-positive bacteria by binding to chemicals essential to forming cell walls. Because this mechanism of action does not involve proteins, researchers think bacteria will be far less likely to develop resistance to teixobactin than to the many current antibiotics that target proteins. Teixobactin is not active against Gram-negative bacteria, however, which include the deadly and rapidly emerging threat of Klebsiella and other carbapenem-resistant Enterobacteriaceae.
Kim Lewis, PhD, MSc, the senior author of the Nature article, and colleagues cultivated teixobactin in the laboratory by mixing 1 g of soil with water and nutrient-rich broth and then pipetting the mixture onto a miniature device, called an iChip, capable of trapping a single microbe in each of its many wells. The iChip was then placed in a bucket of soil to incubate for 1 month. Many of the microbes replicated and formed thriving colonies, which were then removed from the iChip and cultivated on petri dishes.
In collaboration with colleagues from Germany, England, and NovoBiotic Pharmaceuticals, Dr. Lewis' team used the iChip approach to study 10,000 different species of soil bacteria. The researchers reportedly isolated more than 25 potential new drug compounds, including a number of possible antibiotics, an anticancer agent, and a compound that specifically targets the bacteria that cause tuberculosis.1
More safety and efficacy testing is needed in animal models before clinical trials can be conducted in humans, which could be as soon as 2 years from now.
NovoBiotic Pharmaceuticals owns the patent for the new molecule. Several of the researchers have financial stakes in the company. Financial support for the research also came from the National Institutes of Health and the German government.n
1. Collins F. Digging up new antibiotics. http://directorsblog.nih.gov/2015/01/13/digging-up-new-antibiotics. National Institutes of Health website. Accessed February 19, 2015.
2. Ling LL, Schneider T, Peoples AJ, et al. A new antibiotic kills pathogens without detectable resistance. Nature. 2015;517:455-459.