A multidrug resistance plasmid contains the molecular switch for type VI secretion in Acinetobacter baumannii

Brent S. Weber, Pek Man Ly, Joshua N. Irwin, Stefan Pukatzki, Mario F. Feldman

Research output: Contribution to journalArticle

75 Scopus citations

Abstract

Infections with Acinetobacter baumannii, one of the most troublesome and least studied multidrug-resistant superbugs, are increasing at alarming rates. A. baumannii encodes 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 of A. baumannii, for which the regulatory mechanisms are unknown. Here, we show that several multidrug-resistant strains of A. baumannii harbor 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 renders A. baumannii susceptible 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.

Original languageEnglish
Pages (from-to)9442-9447
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume112
Issue number30
DOIs
StatePublished - Jul 28 2015

Keywords

  • Acinetobacter baumannii
  • Antibiotic resistance
  • Bacterial secretion
  • Plasmid
  • T6SS

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