Nature Reviews Microbiology 11, 224–225 (2013); doi:10.1038/nrmicro3004

In this Research Highlight, we omitted to mention an earlier publication in which interactions between heterologous type VI secretion system (T6SS)-positive species had also been demonstrated. We have now added the following reference to alert readers to this:

LeRoux, M. et al. Quantitative single-cell characterization of bacterial interactions reveals type VI secretion is a double-edged sword. Proc. Natl. Acad. Sci. USA 109, 19804–19809 (2012)

We apologize to the authors of the earlier study for this omission, and to readers for any confusion caused.