Once the authors identified the compound teixobactin from the uncultured bacteria, they showed that it had excellent in-vitro activity against Gram-positive bacteria including enterococci, Clostridium difficile, Bacillus anthracis, and Staphylococcus aureus (including vancomycin intermediate resistant culture strains). They also tested the in-vivo efficacy against methicillin-resistant S. aureus and Streptococcus pneumoniae in a mouse model and reported excellent results. Intriguingly, the authors said that “resistance has not developed … suggesting that the target is not a protein” and since there exists a similar lack of resistance development to vancomycin through mutations, they postulated “that teixobactin could be acting against the same (lipid II) target.”
I agree with Dr. William Schaffner's comments in the New York Times as he called the study/method “ingenious” yet also cautioned that “it's at the test-tube and the mouse level, and mice are not men or women, and so moving beyond that is a large step, and many compounds have failed.” I would add one additional caveat: teixobactin had little activity against most Gram-negative bacteria including Erichia coli, Klebsiella and Pseudomonas. Since the real resistance crisis is in multidrug-resistant Gram-negatives (think carbapenem-resistant Enterobacteriaceae, New Delhi metallo-beta-lactamase-1), we better get back to digging in the dirt.
