<i>A</i>. <i>baumannii</i> K-locus polysaccharides facilitate intrinsic antibiotic resistance.

<p><b>A, B.</b> Colony forming efficiency (CFE) tests with WT and mutant <i>A</i>. <i>baumannii</i>. 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 (<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004691#ppat.1004691.t001" target="_blank">Table 1</a>) 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. <b>A</b>. Mutants deficient in capsular exopolysaccharide were tested; the ∆<i>wzc</i> isolate tested was isolate 16. <b>B</b>. Mutants deficient in capsular exopolysaccharide and LPS were tested. <b>C</b>. At concentrations resulting in ~100% CFE (arrows in <b>B</b>), Em and Rif reduce the growth of ∆KL3 but not WT bacteria. Scale bar: 1cm.