In Vitro Acinetobacter baumannii Colistin Resistant Mutants Show an Increased LPS Production and Outer Membrane Protein Modification (original) (raw)

Abstract

Background: Acinetobacter baumannii is an opportunistic pathogen causing infections mainly in patients in intensive care units, where the extensive use of antimicrobial agents can select for the emergence of multidrug resistant strains. Colistin remains as the last solution to treat infections caused by these multiresistant clinical isolates. The objective of this work was to determine the mechanisms of resistance to colistin in an A.baumannii clinical isolate. Methods: A. baumannii clinical isolate 77778 was subjected to increased colistin concentrations. The final mutant strain was able to grow in media with 256 mg/L of colistin and was stable to passages in non-selective media. LPS were obtained after proteinase K digestion of whole cells and were separated by SDS-PAGE. Cultures were grown in presence and absence of different amounts of colistin. Cell envelope protein extracts were also analysed by SDS-PAGE electrophoresis to study changes in protein expression. Results: The LPS ...

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