Representative 1,2′-DNA efflux curves of 3-AG100-derived AcrB binding pocket mutants.

<p>After preloading with 4 µM 1,2′-DNA the cells were energized at 100 s with 50 mM glucose. Fluorescence intensity is given as relative fluorescence units (RFU) with preenergization levels adjusted to 100 RFU.</p

Increased quenching of 1,2′-DNA fluorescence at higher dye loading concentrations (DLCs) in strain 3-AG100.

<p>Depicted are relative fluorescence units (RFU) of deenergized cells preloaded with 1,2′-DNA after resuspension in fresh PPB. All experiments were done in triplicate. The error bars show the standard deviation.</p

Microarray-Based Genotyping and Clinical Outcomes of <i>Staphylococcus aureus</i> Bloodstream Infection: An Exploratory Study

<div><p>The clinical course of <i>Staphylococcus aureus</i> bacteremia varies extensively. We sought to determine the relationship between genetic characteristics of the infecting pathogen and clinical outcomes in an exploratory study. In two study centers, 317 blood culture isolates were analyzed by DNA microarray and <i>spa</i> genotyping. By uni- and multivariate regression analyses associations of genotype data with 30-day all-cause mortality, severe sepsis/septic shock, disseminated disease, endocarditis, and osteoarticular infection were investigated. Univariate analysis showed significant association between <i>S. aureus</i> genes/gene-clusters or clonal complexes and clinical endpoints. For example CC15 was associated with 30-day mortality and CC22 with osteoarticular infection. In multivariate analysis methicillin resistance (<i>mecA,</i> OR 4.8 [1.43–16.06]) and the beta-lactamase-gene (<i>bla</i>, OR 3.12 [1.17–8.30]) remained independently associated with 30-day mortality. The presence of genes for enterotoxins (<i>sed/sej/ser</i>) was associated with endocarditis (OR 5.11 [1.14–18.62]). Host factors such as McCabe classification (OR 4.52 [2.09–9.79] for mortality), age (OR 1.06 [1.03–1.10] per year), and community-acquisition (OR 3.40 [1.31–8.81]) had a major influence on disease severity, dissemination and mortality. Individual genotypes and clonal complexes of <i>S. aureus</i> can only partially explain clinical features and outcomes of <i>S. aureus</i> bacteremia. Genotype-phenotype association studies need to include adjustments for host factors like age, comorbidity and community-acquisition.</p></div

Patient characteristics and demographic data of 317 patients with SAB.

§<p>Three patients were lost to follow-up.</p

Prevalence of major virulence factors and resistance determinants in 317 SAB isolates.

<p>Genes encoding exfoliative toxin serotype A and B (<i>etA</i>, <i>etB</i>), exfoliative toxin D (<i>etD</i>), PVL (<i>lukF-PV, lukS-PV</i>) were detected in <5% of isolates. Fusidic acid resistance (<i>far1</i>), surface protein involved in biofilm formation (<i>bap</i>) genes and capsule type 1 genes (capH1/I1/J1/K1) were not detected.</p><p>Genes encoding staphylococcal superantigen-like protein-1,-2,-4,-5,-7,-9,-10 (<i>ssl</i>-genes), clumping factor A/B (<i>clfA/B</i>), hemolysin alpha (<i>hla</i>), aureolysin (<i>aur</i>), intercellular adhesion protein A/C (<i>icaA</i>, <i>icaC</i>) and biofilm PIA synthesis protein D (<i>icaD</i>), fibronectin-binding protein A (<i>fnbA</i>), fibrinogen binding protein (<i>fib</i>) were detected in >95% of isolates. The hemolysin delta gene (<i>hld</i>) was found in 100% of isolates.</p

Logistic regression analysis for endpoint osteoarticular infection adjusted for age, study center, sex, comorbidity, mode of acquisition and methicillin resistance.

<p>Logistic regression analysis for endpoint osteoarticular infection adjusted for age, study center, sex, comorbidity, mode of acquisition and methicillin resistance.</p

Multivariate logistic regression analysis for endpoint infective endocarditis.

<p>OR Odds ratio. CI Confidence interval. & Mandatory variable.</p>#<p>Due to a contingency coefficient of 1.0 of <i>sed</i>, <i>sej</i>, <i>ser</i>, only <i>sed</i> was included in the multivariable logistic regression model.</p

Multivariate logistic regression analyses for endpoints 30-day mortality, severe sepsis or septic shock and disseminated disease.

§<p>Three patients were lost to follow-up.</p><p>&Mandatory variable.</p>#<p>Due to an extremely high correlation of <i>blaI</i> and <i>blaR</i> (contingency coefficient 1.0 of <i>blaR</i> with <i>blaZ</i>), only <i>blaZ</i> was included in the multivariate logistic regression model (endpoint 30-day mortality).</p>§<p>Due to a high correlation of <i>sed/sej/ser</i> and <i>aadD</i> (contingency coefficient 0.71), only <i>sed/sej/ser</i> was included in the multivariate logistic regression model (endpoint severe sepsis/septic shock). If <i>aadD</i> is included instead, results are OR 4.23 (95% CI 0.91–19.61, p = 0.07) for <i>aadD</i> and OR 1.80 (95% CI 1.04–3.10, p = 0.03) for <i>fosB</i>.</p>†<p>Due to a contingency coefficient of 1.0 of <i>sed</i>, <i>sej</i>, <i>ser</i>, only <i>sed</i> was included in the multivariable logistic regression model (endpoint disseminated disease).</p>‡<p>If 22 SAB cases with initiation of adequate antibiotic therapy ≥3 days after onset of SAB were excluded from the analysis CC15 exhibited a marginally significant effect with OR 2.81 (95% CI 1.0–7.91, P = 0.05) whereas mecA lost its significant impact (OR 3.35, 95% CI 0.79–14.21, p = 0.10). For the other endpoints no significant changes were observed.</p

Comparison of the biofilm-forming capacity of <i>S</i>. <i>aureus</i> isolates from prosthetic joint infection (PJI) and uninfected prosthetic joint (PJU) groups.

<p>Values were calculated as percentage capacity to form biofilms relative to <i>S</i>. <i>aureus</i> control strain UAMS-1. Box ends represent the 25^th and 75^th percentiles, and whisker ends represent the minimum and maximum. There was no difference in biofilm-forming capacity between isolates in the PJI and PJU groups.</p

Comparison of the fibronectin binding capacity of <i>S</i>. <i>aureus</i> isolates from prosthetic joint infection (PJI) and uninfected prosthetic joint (PJU) groups.

<p>Values were calculated as percentage capacity to bind fibronectin relative to <i>S</i>. <i>aureus</i> control strain 8325–4. Box ends represent the 25^th and 75^th percentiles, and whisker ends represent the minimum and maximum. There was no difference in fibronectin binding capacity between isolates in the PJI and PJU groups.</p