TABLE 1

Bacterial strains used in this study

StrainDescriptionColistin MIC (μg/ml)Source or reference
ATCC 19606A. baumannii type strain; parent of AL1842 ΔlpxC, AL1851 ΔlpxA, and AL1852 ΔlpxD1American Type Culture Collection
AL1851 ΔlpxADerivate of ATCC 19606; colistin resistant; 445-bp deletion within lpxA6412
AL1852 ΔlpxDDerivate of ATCC 19606; colistin resistant; single base deletion at nucleotide [nt] 364 of lpxD and frame shift after K317>12812
AL1842 ΔlpxCDerivate of ATCC 19606; colistin resistant; 84-bp deletion within lpxC12812
ATCC 19606 pmrBDerivate of ATCC 19606; colistin resistant; single amino acid substitution (Ala227Val) in PmrB. Ala227Val is adjacent to the conserved histidine at the site of phosphorylation (His228).6415
ABRIMA. baumannii clinical strain carrying the carbapenemase OXA-24, isolated in a Spanish nosocomial outbreak in 1997121
ABRIM pmrBDerivate of A. baumannii ABRIM; colistin resistant; single amino acid substitution (Asn353Tyr) in PmrB. This substitution is inside the ATP binding site and may have an effect on the phosphorylation of His228 and thereby on the phosphorylation levels of PmrA.3215
OP50E. coli strain used for maintenance of C. elegansNAa24
  • a NA, not applicable.