Author:
Weber Brent S.,Ly Pek Man,Irwin Joshua N.,Pukatzki Stefan,Feldman Mario F.
Abstract
Infections withAcinetobacter baumannii, one of the most troublesome and least studied multidrug-resistant superbugs, are increasing at alarming rates.A. baumanniiencodes a type VI secretion system (T6SS), an antibacterial apparatus of Gram-negative bacteria used to kill competitors. Expression of the T6SS varies among different strains ofA. baumannii, for which the regulatory mechanisms are unknown. Here, we show that several multidrug-resistant strains ofA. baumanniiharbor a large, self-transmissible resistance plasmid that carries the negative regulators for T6SS. T6SS activity is silenced in plasmid-containing, antibiotic-resistant cells, while part of the population undergoes frequent plasmid loss and activation of the T6SS. This activation results in T6SS-mediated killing of competing bacteria but rendersA. baumanniisusceptible to antibiotics. Our data show that a plasmid that has evolved to harbor antibiotic resistance genes plays a role in the differentiation of cells specialized in the elimination of competing bacteria.
Funder
National Sciences and Engineering Research Council of Canada
Publisher
Proceedings of the National Academy of Sciences
Cited by
147 articles.
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