Molecular epidemiology of Acinetobacter baumannii integrated with genomic resistance island

B. Thapa, T. Chanwit, S. Somporn, C. Dhiraputra
2012 International Journal of Infectious Diseases  
guideline. The strains were also typed by random amplified polymorphic DNA (RAPD). The lipid A from resistance strains were extracted and subjected to the analysis using MALDI-TOF mass spectrometry. Results: Sensitivity to colistin were determined when the MIC is ≤ 2 g/ml according to CLSI guideline. Of the two hundred strains collected, twenty were found to have MIC ranging from 4 to 128 g/ml. The RAPD grouped the resistance strains into five groups. The MALDI-TOF MS revealed that the basic
more » ... ucture of A. buamannii lipid A is the heptaacylated diphosphoryl lipid A (m/z 1910). The resistance strains exhibited the extra peaks at either m/z 2034, 2071 or 2194, which correspond to the additions of phosphoethanolamine, hexosamine or both to lipid A molecule, respectively. The addition of these residues takes place at the phosphate moieties of lipid A thus potentially cancelling the negative charges and may render A. baumannii the resistance to colistin. Conclusion: The analysis of lipid A from Thai A. baumannii colistin resistance strains demonstrates the modification by which the negative charges were eliminated by the addition of small residues and may subsequently lead to the reduction of colistin target.
doi:10.1016/j.ijid.2012.05.610 fatcat:fynj3hbwgbcd5p3fxd2ygowlqa