RT Journal Article
T1 Investigation of Novel pmrB and eptA Mutations in Isogenic Acinetobacter baumannii Isolates Associated with Colistin Resistance and Increased Virulence In Vivo.
A1 Gerson, Stefanie
A1 Betts, Jonathan W
A1 Lucaßen, Kai
A1 Nodari, Carolina Silva
A1 Wille, Julia
A1 Josten, Michaele
A1 Göttig, Stephan
A1 Nowak, Jennifer
A1 Stefanik, Danuta
A1 Roca, Ignasi
A1 Vila, Jordi
A1 Cisneros, José M
A1 La Ragione, Roberto M
A1 Seifert, Harald
A1 Higgins, Paul G
K1 Acinetobacter
K1 antibiotic resistance
K1 genome analysis
K1 lipid A
K1 virulence
AB Colistin resistance in Acinetobacter baumannii is of great concern and is a threat to human health. In this study, we investigate the mechanisms of colistin resistance in four isogenic pairs of A. baumannii isolates displaying an increase in colistin MICs. A mutation in pmrB was detected in each colistin-resistant isolate, three of which were novel (A28V, I232T, and ΔL9-G12). Increased expression of pmrC was shown by semi-quantitative reverse transcription-PCR (qRT-PCR) for three colistin-resistant isolates, and the addition of phosphoethanolamine (PEtN) to lipid A by PmrC was revealed by mass spectrometry. Interestingly, PEtN addition was also observed in some colistin-susceptible isolates, indicating that this resistance mechanism might be strain specific and that other factors could contribute to colistin resistance. Furthermore, the introduction of pmrAB carrying the short amino acid deletion ΔL9-G12 into a pmrAB knockout strain resulted in increased pmrC expression and lipid A modification, but colistin MICs remained unchanged, further supporting the strain specificity of this colistin resistance mechanism. Of note, a mutation in the pmrC homologue eptA and a point mutation in ISAba1 upstream of eptA were associated with colistin resistance and increased eptA expression, which is a hitherto undescribed resistance mechanism. Moreover, no cost of fitness was observed for colistin-resistant isolates, while the virulence of these isolates was increased in a Galleria mellonella infection model. Although the mutations in pmrB were associated with colistin resistance, PEtN addition appears not to be the sole factor leading to colistin resistance, indicating that the mechanism of colistin resistance is far more complex than previously suspected and is potentially strain specific.
YR 2019
FD 2019-02-26
LK http://hdl.handle.net/10668/13385
UL http://hdl.handle.net/10668/13385
LA en
DS RISalud
RD Apr 7, 2025