Promoters of Colistin Resistance in Acinetobacter baumannii Infections

Elif Nurtop, Fulya Baylndlr Bilman, Sirin Menekse, Ozlem Kurt Azap, Mehmet Gönen, Onder Ergonul, Fusun Can

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Objectives: We aimed to describe the mechanisms of colistin resistance in Acinetobacter baumannii. Materials and Methods: Twenty-nine patients diagnosed with colistin-resistant A. baumannii infection were included to the study. The mutations in pmrCAB, lpxA, lpxC, and lpxD genes, expression of pmrCAB, carbapenemases, and mcr-1 positivity were studied. Results: Twenty-seven (93%) of the patients received IV colistin therapy during their stay, and the case fatality rate was 45%. All mutations in pmrC and pmrB were found to be accompanied with a mutation in lpxD. The most common mutations were I42V and L150F in pmrC (65%), E117K in lpxD (65%), and A138T in pmrB (58.6%). The colistin minimum inhibitory concentrations (MICs) of the isolates having any of these four mutations were higher than the isolates with no mutations (p < 0.001). The two most common mutations in pmrC (I42V and L150F) were found to be associated with higher expressions of pmrA and pmrC and higher colistin MIC values (p = 0.010 and 0.031). All isolates were blaOXA-23 positive. Conclusion: Coexistence of the lpxD mutation along with mutations in pmrCAB indicates synergistic function of these genes in development of colistin resistance in A. baumannii.

Original languageEnglish (US)
Pages (from-to)997-1002
Number of pages6
JournalMicrobial Drug Resistance
Issue number7
StatePublished - Sep 2019


  • A. baumannii
  • colistin
  • resistance

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Pharmacology
  • Microbiology (medical)


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