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Supplementary Materials for:The effects of β-lactam antibiotics on surface modifications of multidrug-resistant Escherichia coli:A multiscale approachSamuel C. Uzoechi1and Nehal I. Abu-Lail2*1Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 991642Department of Biomedical Engineering, The University of Texas at San Antonio, San Antonio, TX, 78249*Corresponding Author: Nehal I. Abu-LailDepartment of Biomedical EngineeringThe University of Texas at San AntonioOne UTSA CircleAET 1.102San Antonio, TX, 78249210-458-8131nehal.abu-lail@utsa.edu Summary of ContentNumber of Pages: 14Number of Figures: 6Number of Tables: 2S.1 Morphology of Cells as a Function of Ampicillin Treatment as Imaged by AFM. MDR-E. coli cells, representative of the different strains investigated, were imaged under DI water with a Multimode AFM equipped with a Nanoscope IIIa controller and extender module (Bruker AXS Inc.) before and after being exposed to various MICs of ampicillin with a Multimode AFM equipped with a Nanoscope IIIa controller and extender module (Bruker AXS Inc.). The AFM height [ REF _Ref505367670 \h \* MERGEFORMAT Figure S1A inset] and phase images were captured concurrently in every single scan. Using the standard AFM Nanoscope Analysis 1.5 software (Bruker, Camarillo, CA), the dimensions (length, width, and height) of individual bacterial cells were characterized for each treatment. To obtain the dimensions, sectional lines were traced on the bacterial images as shown in REF _Ref505367670 \h \* MERGEFORMAT Figure S1A. The surface area (SA) and surface area to volume ratio (SA/V) of individual cells were estimated by approximating cells as ellipsoids. The surface area and volume of an ellipsoid are given by: SA=4πab1.6+ac1.6+bc1.631/1.6(S SEQ Eq \* MERGEFORMAT 1)V=43πabc (S SEQ Eq \* MERGEFORMAT 2)The letters a, b and c describe the semi-axes from the origin of the ellipsoid to its surface and represents here length, width, and height, respectively as shown in REF _Ref505367670 \h \* MERGEFORMAT Figure S1B.Figure S1: The gray and black section lines to the left correspond the same colors shown on the image in the inset. The cross sections can be analyzed to get the length (L), width (W) and maximum height (H) of the bacterial cell. (B) A three-dimensional schematic of an ellipsoid that models the dimensions of bacteria introduced in equations S1 and S2.S.2 Analysis of the Surface Roughness of Individual Bacterial Cells. The surface roughness values of individual MDR-E. coli cells were estimated using data obtained from the AFM height images of individual cells. Using the freely-available online Gwyddion v2.17 software (), the root-mean-square roughness (RMS) was determined over a constant 0.60×0.60 ?m2 area for each bacterium surface ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1074/jbc.M110.130955","ISBN":"0021-9258","ISSN":"1083351X","PMID":"20566635","abstract":"The potential of antimicrobial peptides (AMPs) as an alternative to conventional therapies is well recognized. Insights into the biological and biophysical properties of AMPs are thus key to understanding their mode of action. In this study, the mechanisms adopted by two AMPs in disrupting the gram-negative Escherichia coli bacterial envelope were explored. BP100 is a short cecropin A-melittin hybrid peptide known to inhibit the growth of phytopathogenic gram-negative bacteria. pepR, on the other hand, is a novel AMP derived from the dengue virus capsid protein. Both BP100 and pepR were found to inhibit the growth of E. coli at micromolar concentrations. Zeta potential measurements of E. coli incubated with increasing peptide concentrations allowed for the establishment of a correlation between the minimal inhibitory concentration (MIC) of each AMP and membrane surface charge neutralization. While a neutralization-mediated killing mechanism adopted by either AMP is not necessarily implied, the hypothesis that surface neutralization occurs close to MIC values was confirmed. Atomic force microscopy (AFM) was then employed to visualize the structural effect of the interaction of each AMP with the E. coli cell envelope. At their MICs, BP100 and pepR progressively destroyed the bacterial envelope, with extensive damage already occurring 2 h after peptide addition to the bacteria. A similar effect was observed for each AMP in the concentration-dependent studies. At peptide concentrations below MIC values, only minor disruptions of the bacterial surface occurred.","author":[{"dropping-particle":"","family":"Alves","given":"Carla S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Melo","given":"Manuel N.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Franquelim","given":"Henri G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ferre","given":"Rafael","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Planas","given":"Marta","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Feliu","given":"Lidia","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bardají","given":"Eduard","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kowalczyk","given":"Wioleta","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Andreu","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Santos","given":"Nuno C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandes","given":"Miguel X.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Castanho","given":"Miguel A R B","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Biological Chemistry","id":"ITEM-1","issue":"36","issued":{"date-parts":[["2010"]]},"page":"27536-27544","title":"Escherichia coli cell surface perturbation and disruption induced by antimicrobial peptides BP100 and pepR","type":"article-journal","volume":"285"},"uris":[""]}],"mendeley":{"formattedCitation":"(Alves <i>et al.</i>, 2010)","manualFormatting":"(Alves et al., 2010","plainTextFormattedCitation":"(Alves et al., 2010)","previouslyFormattedCitation":"(Alves <i>et al.</i>, 2010)"},"properties":{"noteIndex":0},"schema":""}(Alves et al., 2010; ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.bbamem.2007.01.014","ISBN":"0005-2736","ISSN":"00052736","PMID":"17320813","abstract":"A novel approach to the study of RBCs based on the collection of three-dimensional high-resolution AFM images and on the measure of the surface roughness of their plasma membrane is presented. The dependence of the roughness from several parameters of the imaging was investigated and a general rule for a trustful analysis and comparison has been suggested. The roughness of RBCs is a morphology-related parameter which has been shown to be characteristic of the single cells composing a sample, but independent of the overall geometric shape (discocyte or spherocyte) of the erythrocytes, thus providing extra-information with respect to a conventional morphology study. The use of the average roughness value as a label of a whole sample was tested on different kinds of samples. Analyzed data revealed that the quantitative roughness value does not change after treatment of RBCs with various commonly used fixation and staining methods while a drastic decrease occurs when studying cells with membrane-skeletal alteration both naturally occurring or artificially induced by chemical treatments. The present method provides a quantitative and powerful tool for a novel approach to the study of erythrocytes structure through an ultrastructural morphological analysis with the potential to give information, in a non-invasive way, on the RBCs function. ? 2007 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Girasole","given":"M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pompeo","given":"G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cricenti","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Congiu-Castellano","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Andreola","given":"F.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Serafino","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Frazer","given":"B. H.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Boumis","given":"G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Amiconi","given":"G.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Biochimica et Biophysica Acta - Biomembranes","id":"ITEM-1","issue":"5","issued":{"date-parts":[["2007"]]},"page":"1268-1276","title":"Roughness of the plasma membrane as an independent morphological parameter to study RBCs: A quantitative atomic force microscopy investigation","type":"article-journal","volume":"1768"},"uris":[""]}],"mendeley":{"formattedCitation":"(Girasole <i>et al.</i>, 2007)","manualFormatting":"Girasole et al., 2007)","plainTextFormattedCitation":"(Girasole et al., 2007)","previouslyFormattedCitation":"(Girasole <i>et al.</i>, 2007)"},"properties":{"noteIndex":0},"schema":""}Girasole et al., 2007). The RMS of the height distribution is represented by Equation S3.RRMS?=?i=1N (Zi-Zave)2N-1(S3)Where N is the number of data points measured within a given area, Zi is the current height value, and Zave is the average height value within a given area ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1074/jbc.M110.130955","ISBN":"0021-9258","ISSN":"1083351X","PMID":"20566635","abstract":"The potential of antimicrobial peptides (AMPs) as an alternative to conventional therapies is well recognized. Insights into the biological and biophysical properties of AMPs are thus key to understanding their mode of action. In this study, the mechanisms adopted by two AMPs in disrupting the gram-negative Escherichia coli bacterial envelope were explored. BP100 is a short cecropin A-melittin hybrid peptide known to inhibit the growth of phytopathogenic gram-negative bacteria. pepR, on the other hand, is a novel AMP derived from the dengue virus capsid protein. Both BP100 and pepR were found to inhibit the growth of E. coli at micromolar concentrations. Zeta potential measurements of E. coli incubated with increasing peptide concentrations allowed for the establishment of a correlation between the minimal inhibitory concentration (MIC) of each AMP and membrane surface charge neutralization. While a neutralization-mediated killing mechanism adopted by either AMP is not necessarily implied, the hypothesis that surface neutralization occurs close to MIC values was confirmed. Atomic force microscopy (AFM) was then employed to visualize the structural effect of the interaction of each AMP with the E. coli cell envelope. At their MICs, BP100 and pepR progressively destroyed the bacterial envelope, with extensive damage already occurring 2 h after peptide addition to the bacteria. A similar effect was observed for each AMP in the concentration-dependent studies. At peptide concentrations below MIC values, only minor disruptions of the bacterial surface occurred.","author":[{"dropping-particle":"","family":"Alves","given":"Carla S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Melo","given":"Manuel N.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Franquelim","given":"Henri G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ferre","given":"Rafael","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Planas","given":"Marta","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Feliu","given":"Lidia","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bardají","given":"Eduard","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kowalczyk","given":"Wioleta","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Andreu","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Santos","given":"Nuno C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandes","given":"Miguel X.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Castanho","given":"Miguel A R B","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Biological Chemistry","id":"ITEM-1","issue":"36","issued":{"date-parts":[["2010"]]},"page":"27536-27544","title":"Escherichia coli cell surface perturbation and disruption induced by antimicrobial peptides BP100 and pepR","type":"article-journal","volume":"285"},"uris":[""]}],"mendeley":{"formattedCitation":"(Alves <i>et al.</i>, 2010)","manualFormatting":"(Alves et al., 2010","plainTextFormattedCitation":"(Alves et al., 2010)","previouslyFormattedCitation":"(Alves <i>et al.</i>, 2010)"},"properties":{"noteIndex":0},"schema":""}(Alves et al., 2010; ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.bbamem.2007.01.014","ISBN":"0005-2736","ISSN":"00052736","PMID":"17320813","abstract":"A novel approach to the study of RBCs based on the collection of three-dimensional high-resolution AFM images and on the measure of the surface roughness of their plasma membrane is presented. The dependence of the roughness from several parameters of the imaging was investigated and a general rule for a trustful analysis and comparison has been suggested. The roughness of RBCs is a morphology-related parameter which has been shown to be characteristic of the single cells composing a sample, but independent of the overall geometric shape (discocyte or spherocyte) of the erythrocytes, thus providing extra-information with respect to a conventional morphology study. The use of the average roughness value as a label of a whole sample was tested on different kinds of samples. Analyzed data revealed that the quantitative roughness value does not change after treatment of RBCs with various commonly used fixation and staining methods while a drastic decrease occurs when studying cells with membrane-skeletal alteration both naturally occurring or artificially induced by chemical treatments. The present method provides a quantitative and powerful tool for a novel approach to the study of erythrocytes structure through an ultrastructural morphological analysis with the potential to give information, in a non-invasive way, on the RBCs function. ? 2007 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Girasole","given":"M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pompeo","given":"G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cricenti","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Congiu-Castellano","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Andreola","given":"F.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Serafino","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Frazer","given":"B. H.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Boumis","given":"G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Amiconi","given":"G.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Biochimica et Biophysica Acta - Biomembranes","id":"ITEM-1","issue":"5","issued":{"date-parts":[["2007"]]},"page":"1268-1276","title":"Roughness of the plasma membrane as an independent morphological parameter to study RBCs: A quantitative atomic force microscopy investigation","type":"article-journal","volume":"1768"},"uris":[""]}],"mendeley":{"formattedCitation":"(Girasole <i>et al.</i>, 2007)","manualFormatting":"Girasole et al., 2007)","plainTextFormattedCitation":"(Girasole et al., 2007)","previouslyFormattedCitation":"(Girasole <i>et al.</i>, 2007)"},"properties":{"noteIndex":0},"schema":""}Girasole et al., 2007). S.3 Contact Angle Measurements of Bacterial Cells. Cells harvested at the late exponential phase of growth were centrifuged and washed three times in 0.2 ?m filtered DI water. Bacterial pellets were resuspended in DI water and filtered through a cellulose filter membrane with a pore diameter of 0.45 mm (Sartorius, Aubagne, France) using negative pressure ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.jcis.2011.03.025","ISBN":"2122633255","ISSN":"00219797","PMID":"21459385","abstract":"The work of adhesion that governs the interactions between pathogenic Listeria monocytogenes and silicon nitride in water was probed for individual cells using atomic force microscopy and for lawns of cells using contact angle measurements combined with a thermodynamic-based harmonic mean model. The work of adhesion was probed for cells cultured under variable pH conditions of growth that ranged from pH 5 to pH 9. Our results indicated that L. monocytogenes cells survived and adapted well to the chemical stresses applied. For all pH conditions investigated, a transition was observed in the generation time, physiochemical properties, biopolymer grafting density and bioadhesion for cells cultured in media adjusted to pH 7 of growth. In media with pH 7, the generation time for the bacterial cells was lowest, the specific growth rate constant was highest, the cells were the most polar, cells displayed the highest grafting density of surface biopolymers and the highest bioadhesion to silicon nitride in water represented in terms of the work of adhesion. When compared, the work of adhesion values quantified between silicon nitride and lawns of L. monocytogenes cells were linearly correlated with the work of adhesion values quantified between silicon nitride and individual L. monocytogenes cells. ?? 2011.","author":[{"dropping-particle":"","family":"Park","given":"Bong Jae","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Abu-Lail","given":"Nehal I.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Colloid and Interface Science","id":"ITEM-1","issue":"2","issued":{"date-parts":[["2011"]]},"page":"611-620","publisher":"Elsevier Inc.","title":"The role of the pH conditions of growth on the bioadhesion of individual and lawns of pathogenic Listeria monocytogenes cells","type":"article-journal","volume":"358"},"uris":[""]}],"mendeley":{"formattedCitation":"(Park and Abu-Lail, 2011)","plainTextFormattedCitation":"(Park and Abu-Lail, 2011)","previouslyFormattedCitation":"(Park and Abu-Lail, 2011)"},"properties":{"noteIndex":0},"schema":""}(Park and Abu-Lail, 2011). The bacterial lawns formed on the filter membrane were placed in a Petri-dish containing 1% (w/v) Bacto agar (Difco, Detroit, Michigan) prepared in filtered DI water supplemented with 10% glycerol to maintain a constant moisture during the measurements. Bacterial contact angles of the suspended lawns were measured using three probe liquids with different polarities. These were ultrapure water, H2O (polar, 18.2 mΩ cm and ε = 78.5%), Formamide, CH3NO (polar, ε = 111, 99.5%) and Diiodomethane, CH2I2 (apolar, ε = 5.32, 99%). ? refers to the dielectric constant of the solvent. A 1 ?L droplet volume of each of the three probe liquids was dropped on the bacterial lawn with at least 10 – 20 different locations tested. Contact angles of the liquid drops formed on the bacterial lawns were then determined using a contact angle analyzer (AST product Inc., Billerica, MA). The volume of the probe liquid drop is much larger than the roughness of the lawn and as such roughness did not affect our contact angles measured ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.jcis.2011.03.025","ISBN":"2122633255","ISSN":"00219797","PMID":"21459385","abstract":"The work of adhesion that governs the interactions between pathogenic Listeria monocytogenes and silicon nitride in water was probed for individual cells using atomic force microscopy and for lawns of cells using contact angle measurements combined with a thermodynamic-based harmonic mean model. The work of adhesion was probed for cells cultured under variable pH conditions of growth that ranged from pH 5 to pH 9. Our results indicated that L. monocytogenes cells survived and adapted well to the chemical stresses applied. For all pH conditions investigated, a transition was observed in the generation time, physiochemical properties, biopolymer grafting density and bioadhesion for cells cultured in media adjusted to pH 7 of growth. In media with pH 7, the generation time for the bacterial cells was lowest, the specific growth rate constant was highest, the cells were the most polar, cells displayed the highest grafting density of surface biopolymers and the highest bioadhesion to silicon nitride in water represented in terms of the work of adhesion. When compared, the work of adhesion values quantified between silicon nitride and lawns of L. monocytogenes cells were linearly correlated with the work of adhesion values quantified between silicon nitride and individual L. monocytogenes cells. ?? 2011.","author":[{"dropping-particle":"","family":"Park","given":"Bong Jae","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Abu-Lail","given":"Nehal I.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Colloid and Interface Science","id":"ITEM-1","issue":"2","issued":{"date-parts":[["2011"]]},"page":"611-620","publisher":"Elsevier Inc.","title":"The role of the pH conditions of growth on the bioadhesion of individual and lawns of pathogenic Listeria monocytogenes cells","type":"article-journal","volume":"358"},"uris":[""]}],"mendeley":{"formattedCitation":"(Park and Abu-Lail, 2011)","plainTextFormattedCitation":"(Park and Abu-Lail, 2011)","previouslyFormattedCitation":"(Park and Abu-Lail, 2011)"},"properties":{"noteIndex":0},"schema":""}(Park and Abu-Lail, 2011). The contact angles were measured within 15-20 minutes before the drying time of each bacterial strain. Drying time for MDR-E. coli lawns were determined to be ～25?minutes. The drying time is described as the time needed for the water contact angles to reach a plateau with time and depicts that the moisture of the cellular exterior is evaporated while the cells are not dehydrated ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.jcis.2011.03.025","ISBN":"2122633255","ISSN":"00219797","PMID":"21459385","abstract":"The work of adhesion that governs the interactions between pathogenic Listeria monocytogenes and silicon nitride in water was probed for individual cells using atomic force microscopy and for lawns of cells using contact angle measurements combined with a thermodynamic-based harmonic mean model. The work of adhesion was probed for cells cultured under variable pH conditions of growth that ranged from pH 5 to pH 9. Our results indicated that L. monocytogenes cells survived and adapted well to the chemical stresses applied. For all pH conditions investigated, a transition was observed in the generation time, physiochemical properties, biopolymer grafting density and bioadhesion for cells cultured in media adjusted to pH 7 of growth. In media with pH 7, the generation time for the bacterial cells was lowest, the specific growth rate constant was highest, the cells were the most polar, cells displayed the highest grafting density of surface biopolymers and the highest bioadhesion to silicon nitride in water represented in terms of the work of adhesion. When compared, the work of adhesion values quantified between silicon nitride and lawns of L. monocytogenes cells were linearly correlated with the work of adhesion values quantified between silicon nitride and individual L. monocytogenes cells. ?? 2011.","author":[{"dropping-particle":"","family":"Park","given":"Bong Jae","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Abu-Lail","given":"Nehal I.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Colloid and Interface Science","id":"ITEM-1","issue":"2","issued":{"date-parts":[["2011"]]},"page":"611-620","publisher":"Elsevier Inc.","title":"The role of the pH conditions of growth on the bioadhesion of individual and lawns of pathogenic Listeria monocytogenes cells","type":"article-journal","volume":"358"},"uris":[""]}],"mendeley":{"formattedCitation":"(Park and Abu-Lail, 2011)","plainTextFormattedCitation":"(Park and Abu-Lail, 2011)","previouslyFormattedCitation":"(Park and Abu-Lail, 2011)"},"properties":{"noteIndex":0},"schema":""}(Park and Abu-Lail, 2011).S.4 Surface Free Energy Calculations. Interfacial polar Lewis acid-base (AB) and apolar Lifshitz-van der Waals (LW) surface interactions have been proposed to govern the initial steps of bacterial adhesion ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/C2009-0-21560-1","ISBN":"9780123751829","ISSN":"1098-6596","PMID":"25246403","abstract":"This reference describes the role of various intermolecular and interparticle forces in determining the properties of simple systems such as gases, liquids and solids, with a special focus on more complex colloidal, polymeric and biological systems. The book provides a thorough foundation in theories and concepts of intermolecular forces, allowing researchers and students to recognize which forces are important in any particular system, as well as how to control these forces. This third edition is expanded into three sections and contains five new chapters over the previous edition. ? starts from the basics and builds up to more complex systems ? covers all aspects of intermolecular and interparticle forces both at the fundamental and applied levels ? multidisciplinary approach: bringing together and unifying phenomena from different fields ? This new edition has an expanded Part III and new chapters on non-equilibrium (dynamic) interactions, and tribology (friction forces). ? 2011 Elsevier Inc. All rights reserved.","author":[{"dropping-particle":"","family":"Israelachvili","given":"Jacob","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Intermolecular and Surface Forces","id":"ITEM-1","issued":{"date-parts":[["2011"]]},"title":"Intermolecular and Surface Forces","type":"book"},"uris":["",""]}],"mendeley":{"formattedCitation":"(Israelachvili, 2011)","plainTextFormattedCitation":"(Israelachvili, 2011)","previouslyFormattedCitation":"(Israelachvili, 2011)"},"properties":{"noteIndex":0},"schema":""}(Israelachvili, 2011). The LW and AB surface interactions consist of electron-acceptor (?s+) and electron-donor (?s-) interaction components ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/jmr.618","ISBN":"1099-1352","ISSN":"09523499","PMID":"12898668","abstract":"Among the three different non-covalent forces acting in aqueous media, i.e. Lifshitz-van der Waals (LW), Lewis acid-base (AB) and electrical double layer (EL) forces, the AB forces or electron-acceptor/electron-donor interactions are quantitatively by far the predominant ones. A subset of the AB forces acting in water causes the hydrophobic effect, which is the attraction caused by the hydrogen-bonding (AB) free energy of cohesion between the water molecules which surround all apolar as well as polar molecules and particles when they are immersed in water. As the polar energy of cohesion among water molecules is an innate property of water, the hydrophobic attraction (due to the hydrophobic effect) is unavoidably always present in aqueous media and has a value of DeltaG(hydrophobic) = -102 mJ/m(2), at 20 degrees C, being equal to the AB free energy of cohesion between the water molecules at that temperature. The strong underlying hydrophobic attraction due to this effect can, however, be surmounted by very hydrophilic molecules and particles that attract water molecules more strongly than the free energy of attraction of these molecules or particles for one another, plus the hydrogen-bonding free energy of cohesion between the water molecules, thus resulting in a net non-electrical double layer repulsion. Each of the three non-covalent forces, LW, AB or EL, any of which can be independently attractive or repulsive, decays, dependent on the circumstances, as a function of distance according to different rules. These rules, following an extended DLVO (XDLVO) approach, are given, as well as the measurement methods for the LW, AB and EL surface thermodynamic properties, determined at \"contact\". The implications of the resulting hydrophobic attractive and hydrophilic repulsive free energies, as a function of distance, are discussed with respect to specific and aspecific interactions in biological systems. The discussion furnishes a description of the manner by which shorter-range specific attractions can surmount the usually much stronger long-range aspecific repulsion, and ends with examples of in vitro and in vivo effects of hydrophilization of biopolymers, particles or surfaces by linkage with polyethylene oxide (PEO; also called polyethylene glycol, PEG).","author":[{"dropping-particle":"","family":"Oss","given":"Carel Jan","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Journal of Molecular Recognition","id":"ITEM-1","issue":"4","issued":{"date-parts":[["2003"]]},"page":"177-190","title":"Long-range and short-range mechanisms of hydrophobic attraction and hydrophilic repulsion in specific and aspecific interactions","type":"article-journal","volume":"16"},"uris":[""]}],"mendeley":{"formattedCitation":"(Van Oss, 2003)","plainTextFormattedCitation":"(Van Oss, 2003)","previouslyFormattedCitation":"(Van Oss, 2003)"},"properties":{"noteIndex":0},"schema":""}(Van Oss, 2003). The polar and apolar components of the surface free energy are additive and are described by equations S4 and S5, ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/jmr.618","ISBN":"1099-1352","ISSN":"09523499","PMID":"12898668","abstract":"Among the three different non-covalent forces acting in aqueous media, i.e. Lifshitz-van der Waals (LW), Lewis acid-base (AB) and electrical double layer (EL) forces, the AB forces or electron-acceptor/electron-donor interactions are quantitatively by far the predominant ones. A subset of the AB forces acting in water causes the hydrophobic effect, which is the attraction caused by the hydrogen-bonding (AB) free energy of cohesion between the water molecules which surround all apolar as well as polar molecules and particles when they are immersed in water. As the polar energy of cohesion among water molecules is an innate property of water, the hydrophobic attraction (due to the hydrophobic effect) is unavoidably always present in aqueous media and has a value of DeltaG(hydrophobic) = -102 mJ/m(2), at 20 degrees C, being equal to the AB free energy of cohesion between the water molecules at that temperature. The strong underlying hydrophobic attraction due to this effect can, however, be surmounted by very hydrophilic molecules and particles that attract water molecules more strongly than the free energy of attraction of these molecules or particles for one another, plus the hydrogen-bonding free energy of cohesion between the water molecules, thus resulting in a net non-electrical double layer repulsion. Each of the three non-covalent forces, LW, AB or EL, any of which can be independently attractive or repulsive, decays, dependent on the circumstances, as a function of distance according to different rules. These rules, following an extended DLVO (XDLVO) approach, are given, as well as the measurement methods for the LW, AB and EL surface thermodynamic properties, determined at \"contact\". The implications of the resulting hydrophobic attractive and hydrophilic repulsive free energies, as a function of distance, are discussed with respect to specific and aspecific interactions in biological systems. The discussion furnishes a description of the manner by which shorter-range specific attractions can surmount the usually much stronger long-range aspecific repulsion, and ends with examples of in vitro and in vivo effects of hydrophilization of biopolymers, particles or surfaces by linkage with polyethylene oxide (PEO; also called polyethylene glycol, PEG).","author":[{"dropping-particle":"","family":"Oss","given":"Carel Jan","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Journal of Molecular Recognition","id":"ITEM-1","issue":"4","issued":{"date-parts":[["2003"]]},"page":"177-190","title":"Long-range and short-range mechanisms of hydrophobic attraction and hydrophilic repulsion in specific and aspecific interactions","type":"article-journal","volume":"16"},"uris":[""]}],"mendeley":{"formattedCitation":"(Van Oss, 2003)","plainTextFormattedCitation":"(Van Oss, 2003)","previouslyFormattedCitation":"(Van Oss, 2003)"},"properties":{"noteIndex":0},"schema":""}(Van Oss, 2003).s=sLW+sAB(S4)sAB=2s+s-(S5)Where, ?sLW and ?sAB (apolar or Lifshitz-van der Waals and polar or Lewis acid-base), ?s is the total free energy of component and ?s- and ?s+ are the electron donor and acceptor of surface free energy components, respectively. The latter two can be obtained by solving the Young-Dupré equation of contact angle (?) (Equation S6) ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/jmr.618","ISBN":"1099-1352","ISSN":"09523499","PMID":"12898668","abstract":"Among the three different non-covalent forces acting in aqueous media, i.e. Lifshitz-van der Waals (LW), Lewis acid-base (AB) and electrical double layer (EL) forces, the AB forces or electron-acceptor/electron-donor interactions are quantitatively by far the predominant ones. A subset of the AB forces acting in water causes the hydrophobic effect, which is the attraction caused by the hydrogen-bonding (AB) free energy of cohesion between the water molecules which surround all apolar as well as polar molecules and particles when they are immersed in water. As the polar energy of cohesion among water molecules is an innate property of water, the hydrophobic attraction (due to the hydrophobic effect) is unavoidably always present in aqueous media and has a value of DeltaG(hydrophobic) = -102 mJ/m(2), at 20 degrees C, being equal to the AB free energy of cohesion between the water molecules at that temperature. The strong underlying hydrophobic attraction due to this effect can, however, be surmounted by very hydrophilic molecules and particles that attract water molecules more strongly than the free energy of attraction of these molecules or particles for one another, plus the hydrogen-bonding free energy of cohesion between the water molecules, thus resulting in a net non-electrical double layer repulsion. Each of the three non-covalent forces, LW, AB or EL, any of which can be independently attractive or repulsive, decays, dependent on the circumstances, as a function of distance according to different rules. These rules, following an extended DLVO (XDLVO) approach, are given, as well as the measurement methods for the LW, AB and EL surface thermodynamic properties, determined at \"contact\". The implications of the resulting hydrophobic attractive and hydrophilic repulsive free energies, as a function of distance, are discussed with respect to specific and aspecific interactions in biological systems. The discussion furnishes a description of the manner by which shorter-range specific attractions can surmount the usually much stronger long-range aspecific repulsion, and ends with examples of in vitro and in vivo effects of hydrophilization of biopolymers, particles or surfaces by linkage with polyethylene oxide (PEO; also called polyethylene glycol, PEG).","author":[{"dropping-particle":"","family":"Oss","given":"Carel Jan","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Journal of Molecular Recognition","id":"ITEM-1","issue":"4","issued":{"date-parts":[["2003"]]},"page":"177-190","title":"Long-range and short-range mechanisms of hydrophobic attraction and hydrophilic repulsion in specific and aspecific interactions","type":"article-journal","volume":"16"},"uris":[""]}],"mendeley":{"formattedCitation":"(Van Oss, 2003)","plainTextFormattedCitation":"(Van Oss, 2003)","previouslyFormattedCitation":"(Van Oss, 2003)"},"properties":{"noteIndex":0},"schema":""}(Van Oss, 2003). The subscripts S and L refer to bacterial and liquid phases.?L(1+cos θ) =2?sLW?LLW+ ?s+?L-+ ?s-?L+(S6)S.5 AFM Force MeasurementsFigure S SEQ Figure \* ARABIC 2: A representative tapping mode image of E. coli A5 cells attached to gelatin-coated mica under water. The inset shows how the 25 points were distributed onto the surface of a representative cell. The large image is 10 x 10 μm2. (B) A representative example of a retraction curve obtained between the Si3N4 cantilever and the surface biopolymers of MDR-E. coli A5 strain with red circles indicating locations of adhesion forces.S.6 Quantification of bacterial Biofilm StrengthTable S SEQ Table \* ARABIC 1: The categories of MDR E. coli biofilms as estimated following the approach established by ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"author":[{"dropping-particle":"","family":"Stepanovic","given":"Srdjan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Vukovic","given":"Dragana","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hola","given":"Veronika","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"Di","family":"Bonaventura","given":"Giovanni","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Djukic?","given":"Slobodanka","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Irkovic?","given":"Ivana C?","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ruzicka","given":"Filip","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Apmis","id":"ITEM-1","issue":"3","issued":{"date-parts":[["2007"]]},"page":"891-899","title":"Quanti?cation of Bio?lm in Microtiter Plates: Overview of Testing Conditions and Practical Recommendations for Assessment of Bio?lm Production by Staphylococci","type":"article-journal","volume":"115"},"uris":["",""]}],"mendeley":{"formattedCitation":"(Stepanovic <i>et al.</i>, 2007)","manualFormatting":"Stepanovic et al., 2007","plainTextFormattedCitation":"(Stepanovic et al., 2007)","previouslyFormattedCitation":"(Stepanovic <i>et al.</i>, 2007)"},"properties":{"noteIndex":0},"schema":""}Stepanovic et al., 2007. ODc is the average absorbance of the negative control and OD is the final optical density value of a tested strain. When OD is higher than ODc, a biofilm has formed in the well.Categories of Biofilm FormationCriterion adoptedStrong biofilm former (+++) 4×ODc < ODModerate biofilm former (++) 2×ODc < OD ≤ 4×ODcWeak biofilm former (+) ODc < OD ≤ 2×ODcNone biofilm former (0) OD ≤ ODcS.7 Effect of Ampicillin on Bacterial MorphologyFigure S3: Summary of the dimensions of bacterial cells as analyzed with the AFM Nanoscope Analysis 1.5 software (Bruker, Camarillo, CA). Strains A5 and H5 were treated in the presence of ampicillin at 50 μg/ml MIC and strains D4 and A9 were treated at 45 μg/ml MIC. (A) Data for strain A5 with a total of 36 cells treated for 3 hours and untreated 44 cells. (B) Data for strain D4 with a total of 24 cells treated for 3 hours, 27 cells treated for 8 hours and 31 untreated cells. (C) Data for strain A9 with a total of 21 cells treated for 3 hours, 13 cells treated for 8 hours, and 25 untreated cells. (D) Data for strain H5 with a total of 31 treated cells for 3 hours and 44 untreated cells. *Values are statistically significant between the untreated and treated cells. ** Values statistically significant from the treated cells but not from the untreated cells, p < 0.001, n = 3 independent cultures. Figure S4: Summary of the average surface area (black) and surface area to volume ratio (gray) of each MDR-E. coli strain before and after exposure to ampicillin at strains’ corresponding MICs. (A) Data for strain A5 with a total of 36 cells treated for 3 hours and untreated 44 cells. (B) Data for strain D4 with a total of 24 cells treated for 3 hours, 27 cells treated for 8 hours and 31 untreated cells. (C) Data for strain A9 with a total of 21 cells treated for 3 hours, 13 cells treated for 8 hours, and 25 untreated cells. (D) Data for strain H5 with a total of 31 treated cells for 3 hours and 44 untreated cells. *Values are statistically significant between the untreated and treated cells. ** Values statistically significant from the treated cells but not from the untreated cells, p < 0.001, n = 3 independent cultures. S.8 Fluorescence Imaging of Cells as a Function of Ampicillin Treatment. Figure S5 shows fluorescence microscopy images of individual bacterial cells before and after exposure to ampicillin at the appropriate MIC (50 or 45 μg/ml). Upon exposure to 50 μg/ml ampicillin for 3 hours, images of strain A5 indicated a reduction in the length of cells compared to cellular length with no ampicillin exposure [Figures S5A and S5E]. Strains D4 and A9 images clearly show the elongation of the bacterial cells as they got exposed to ampicillin at MIC for 3 hours compared to their untreated with no ampicillin exposure [Figures S5B to S5F and S5C to S5G]. With ampicillin at 45 or 50 μg/ml treatments for 3 hours, elongation was observed in strains D4, A9 and H5 compared to their untreated cells [Figures S5B, S5C, and S5D]. The results of fluorescence imaging are consistent with dimensions and observations obtained from AFM height images [ REF _Ref505368158 \h \* MERGEFORMAT Figure 2]. Figure S5: Representative images of the four MDR-E. coli strains incubated without (A-D) and with ampicillin for 3 hours at 50 μg/ml (E and H) and at the 45 μg/ml (F and G) above CLSI resistance breakpoint concentration. According to REF _Ref505372536 \h \* MERGEFORMAT Figure S5 images, no cell lysis was observed, and the elongated cells never released their DNA content. It has been reported that antibiotic concentrations that result in cell lysis induced release of DNA which rapidly binds to the SYTO 9 nucleic acid dye and appears clearly in the background of the fluorescent images ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1128/JCM.01675-12","ISBN":"0095-1137","ISSN":"00951137","PMID":"22933604","abstract":"Infections caused by multidrug-resistant Acinetobacter baumannii constitute a major life-threatening problem worldwide, and early adequate antibiotic therapy is decisive for success. For these reasons, rapid detection of antibiotic susceptibility in this pathogen is a clinical challenge. Two variants of the Micromax kit were evaluated for a rapid detection in situ of susceptibility or resistance to meropenem or ciprofloxacin, separately, in 322 clinical isolates. Release of the nucleoid is the criterion of susceptibility to the beta-lactams (carbapenems), whereas diffusion of DNA fragments emerging from the nucleoid characterizes the quinolone activity. All the susceptible and resistant strains were correctly categorized in 100 min according to the MIC results and CLSI criteria. Thus, our technology is a promising tool for rapid identification of carbapenem and quinolone resistance of A. baumannii strains in hospital settings.","author":[{"dropping-particle":"","family":"Bou","given":"Germán","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Otero","given":"Fátima María","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Santiso","given":"Rebeca","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tamayo","given":"María","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernández","given":"María Del Carmen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tomás","given":"María","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gosálvez","given":"Jaime","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernández","given":"José Luis","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Clinical Microbiology","id":"ITEM-1","issue":"11","issued":{"date-parts":[["2012"]]},"page":"3609-3613","title":"Fast assessment of resistance to carbapenems and ciprofloxacin of clinical strains of Acinetobacter baumannii","type":"article-journal","volume":"50"},"uris":[""]}],"mendeley":{"formattedCitation":"(Bou <i>et al.</i>, 2012)","plainTextFormattedCitation":"(Bou et al., 2012)","previouslyFormattedCitation":"(Bou <i>et al.</i>, 2012)"},"properties":{"noteIndex":0},"schema":""}(Bou et al., 2012). The images presented in REF _Ref505372536 \h \* MERGEFORMAT Figure S5 did not show any spread of DNA in the background. We realize that washing with PBS may cover the effects of possible cell lysis as DNA from lysed cells can get solubilized in water and washed away. However, running these assays without washing adversely affects the resolution of the images. We felt it is necessary to remove the cell debris and non-adherent cells by washing for a better resolution ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1371/journal.pone.0016105","ISBN":"1932-6203 (Electronic)\\r1932-6203 (Linking)","ISSN":"19326203","PMID":"21267455","abstract":"Pseudomonas aeruginosa, a gram-negative bacterium of clinical importance, forms more robust biofilm during anaerobic respiration, a mode of growth presumed to occur in abnormally thickened mucus layer lining the cystic fibrosis (CF) patient airway. However, molecular basis behind this anaerobiosis-triggered robust biofilm formation is not clearly defined yet. Here, we identified a morphological change naturally accompanied by anaerobic respiration in P. aeruginosa and investigated its effect on the biofilm formation in vitro. A standard laboratory strain, PAO1 was highly elongated during anaerobic respiration compared with bacteria grown aerobically. Microscopic analysis demonstrated that cell elongation likely occurred as a consequence of defective cell division. Cell elongation was dependent on the presence of nitrite reductase (NIR) that reduces nitrite (NO(2) (-)) to nitric oxide (NO) and was repressed in PAO1 in the presence of carboxy-PTIO, a NO antagonist, demonstrating that cell elongation involves a process to respond to NO, a spontaneous byproduct of the anaerobic respiration. Importantly, the non-elongated NIR-deficient mutant failed to form biofilm, while a mutant of nitrate reductase (NAR) and wild type PAO1, both of which were highly elongated, formed robust biofilm. Taken together, our data reveal a role of previously undescribed cell biological event in P. aeruginosa biofilm formation and suggest NIR as a key player involved in such process.","author":[{"dropping-particle":"","family":"Yoon","given":"Mi Young","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lee","given":"Kang Mu","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Park","given":"Yongjin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yoon","given":"Sang Sun","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"PLoS ONE","id":"ITEM-1","issue":"1","issued":{"date-parts":[["2011"]]},"page":"1-11","title":"Contribution of cell elongation to the biofilm formation of Pseudomonas aeruginosa during anaerobic respiration","type":"article-journal","volume":"6"},"uris":[""]}],"mendeley":{"formattedCitation":"(Yoon <i>et al.</i>, 2011)","plainTextFormattedCitation":"(Yoon et al., 2011)","previouslyFormattedCitation":"(Yoon <i>et al.</i>, 2011)"},"properties":{"noteIndex":0},"schema":""}(Yoon et al., 2011).S.9 Effect of Ampicillin on Bacterial Surface Roughness, Membrane Permeability, Biofilm Formation and Adhesion Forces of MDR-E. coli.Figure S6: Summary of the effects of ampicillin exposure at relevant MICs on the surface characteristics of the MDR-E. coli strains investigated at variable exposure time points. (A) The average bacterial surface RMS (nm). (B) Summary of cellular membrane permeability (MP, %). (C) The average macroscale bacterial biofilm formation of cells. (D) Summary of the average AFM nanoscale adhesion force (Fad) measured between the Si3N4 cantilever and the bacterial surface biopolymers. *Values are statistically significant from the control and treatment group at p < 0.001, n = 3 independent cultures. MIC is (50 or 45 μg/ml) for strains A5 and H5, and D4 and A9 respectively. Above MIC is (65 or 55 μg/ml) for strains A5 and H5, and D4 and A9 respectively.S.10 Effect of Ampicillin on Bacterial Surface Hydrophobicity. Table S2: Contact angles of the bacterial strains measured in water, formamide and diiodomethane and the corresponding surface energy components (mJ/m2). Contact angles were measured for cells untreated with ampicillin as well as for cells treated with ampicillin at the corresponding MIC for 3 hours. The reported contact angles are the means ± standard deviations measured on 15 locations on a given bacterial lawn, * Values are statistically significant from the control, p < 0.001. NT = not treated, n=3 independent cultures.Strain ID a Contact angle (o)b Surface energy component (mJ/m2)θWθDθF?sLW?s+?s-?sAB?sA55026 ± 178 ± 5*25 ± 1*18.78.545.739.458.1NT28 ± 358 ± 328 ± 129.62.841.129.154.4D44529 ± 2*89 ± 9*33 ± 4*13.110.647.444.757.9NT32 ± 266 ± 825 ± 225.45.141.129.154.4A94521 ± 174 ± 924 ± 1*20.86.950.237.258.0NT22 ± 266 ± 721 ± 325.35.248.731.857.1H55028 ± 2*62 ± 525 ± 327.34.145.227.154.4NT26 ± 259 ± 225 ± 229.03.347.325.154.11 θW, θD, and θF are the contact angles of water, diiodomethane, and formamide on MDR-E. coli respectively. 2 ?sLW and ?sAB (Lifshitz-van der Waals and Lewis acid-base) and ?s+ and ?s- are the electron acceptor and donor of surface free energy components of MDR-E. coli respectively.References ADDIN Mendeley Bibliography CSL_BIBLIOGRAPHY Alves, C. S. et al. (2010) ‘Escherichia coli cell surface perturbation and disruption induced by antimicrobial peptides BP100 and pepR’, Journal of Biological Chemistry, 285(36), pp. 27536–27544. doi: 10.1074/jbc.M110.130955.Bou, G. et al. (2012) ‘Fast assessment of resistance to carbapenems and ciprofloxacin of clinical strains of Acinetobacter baumannii’, Journal of Clinical Microbiology, 50(11), pp. 3609–3613. doi: 10.1128/JCM.01675-12.Girasole, M. et al. (2007) ‘Roughness of the plasma membrane as an independent morphological parameter to study RBCs: A quantitative atomic force microscopy investigation’, Biochimica et Biophysica Acta - Biomembranes, 1768(5), pp. 1268–1276. doi: 10.1016/j.bbamem.2007.01.014.Israelachvili, J. (2011) Intermolecular and Surface Forces, Intermolecular and Surface Forces. doi: 10.1016/C2009-0-21560-1.Van Oss, C. J. (2003) ‘Long-range and short-range mechanisms of hydrophobic attraction and hydrophilic repulsion in specific and aspecific interactions’, Journal of Molecular Recognition, 16(4), pp. 177–190. doi: 10.1002/jmr.618.Park, B. J., and Abu-Lail, N. I. (2011) ‘The role of the pH conditions of growth on the bioadhesion of individual and lawns of pathogenic Listeria monocytogenes cells’, Journal of Colloid and Interface Science. Elsevier Inc., 358(2), pp. 611–620. doi: 10.1016/j.jcis.2011.03.025.Stepanovic, S. et al. (2007) ‘Quanti?cation of Bio?lm in Microtiter Plates: Overview of Testing Conditions and Practical Recommendations for Assessment of Bio?lm Production by Staphylococci’, Apmis, 115(3), pp. 891–899.Yoon, M. Y. et al. (2011) ‘Contribution of cell elongation to the biofilm formation of Pseudomonas aeruginosa during anaerobic respiration’, PLoS ONE, 6(1), pp. 1–11. doi: 10.1371/journal.pone.0016105. ................
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