Antibiotic Modulation of Capsular Exopolysaccharide and Virulence in Acinetobacter baumannii
Fig 3
A. baumannii K-locus polysaccharides facilitate intrinsic antibiotic resistance.
A, B. Colony forming efficiency (CFE) tests with WT and mutant A. baumannii. Bacteria were serially diluted, plated onto LB agar or LB agar containing the indicated antibiotics, and the resulting CFU were scored after overnight incubation at 37°C. The limit of detection was approximately 10–6, except for assays with colistin in which the limit of detection was approximately 10–5. MIC (Table 1) is defined as the antibiotic concentration at which CFE drops below 10–3 (dotted line). Data points represent the mean ± SEM from at least two independent cultures. Where not visible, error bars are within the confines of the symbol. The MW of each antibiotic is indicated. A. Mutants deficient in capsular exopolysaccharide were tested; the ∆wzc isolate tested was isolate 16. B. Mutants deficient in capsular exopolysaccharide and LPS were tested. C. At concentrations resulting in ~100% CFE (arrows in B), Em and Rif reduce the growth of ∆KL3 but not WT bacteria. Scale bar: 1cm.