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array:2 [ "etiqueta" => "<span class="elsevierStyleSup">e</span>" "identificador" => "aff0025" ] ] ] 5 => array:4 [ "nombre" => "María" "apellidos" => "Guembe" "email" => array:1 [ 0 => "mariaguembe@hotmail.com" ] "referencia" => array:3 [ 0 => array:2 [ "etiqueta" => "<span class="elsevierStyleSup">a</span>" "identificador" => "aff0005" ] 1 => array:2 [ "etiqueta" => "<span class="elsevierStyleSup">b</span>" "identificador" => "aff0010" ] 2 => array:2 [ "etiqueta" => "<span class="elsevierStyleSup">*</span>" "identificador" => "cor0005" ] ] ] ] "afiliaciones" => array:5 [ 0 => array:3 [ "entidad" => "Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañon, Madrid, Spain" "etiqueta" => "a" "identificador" => "aff0005" ] 1 => array:3 [ "entidad" => "Instituto de Investigación Sanitaria Gregorio Marañon, Madrid, Spain" "etiqueta" => "b" "identificador" => "aff0010" ] 2 => array:3 [ "entidad" => "School of Biology, Universidad Complutense de Madrid, Madrid, Spain" "etiqueta" => "c" "identificador" => "aff0015" ] 3 => array:3 [ "entidad" => "Medicine Department, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain" "etiqueta" => "d" "identificador" => "aff0020" ] 4 => array:3 [ "entidad" => "CIBER Enfermedades Respiratorias-CIBERES, Madrid, Spain" "etiqueta" => "e" "identificador" => "aff0025" ] ] "correspondencia" => array:1 [ 0 => array:3 [ "identificador" => "cor0005" "etiqueta" => "⁎" "correspondencia" => "Corresponding author." ] ] ] ] "titulosAlternativos" => array:1 [ "es" => array:1 [ "titulo" => "La clasificación de cepas de <span class="elsevierStyleItalic">Staphylococcus aureus</span> según la producción de biopelícula varía dependiendo del método utilizado" ] ] "textoCompleto" => "<span class="elsevierStyleSections"><span id="sec0005" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0070">Introduction</span><p id="par0005" class="elsevierStylePara elsevierViewall">Bacterial biofilms are microbial communities that adhere to a surface or an interface and become embedded in an extracellular matrix. Biofilms constitute a significant problem in clinical settings and are responsible for more than 65% of human infections and treatment failures.<a class="elsevierStyleCrossRefs" href="#bib0080"><span class="elsevierStyleSup">1,2</span></a><span class="elsevierStyleItalic">Staphylococcus aureus</span> is a major causative agent of this kind of infection and has been described as a high biofilm-former, mainly in device-related bloodstream infections.<a class="elsevierStyleCrossRef" href="#bib0090"><span class="elsevierStyleSup">3</span></a></p><p id="par0010" class="elsevierStylePara elsevierViewall">Various approaches have been used for the in vitro study of biofilm production.<a class="elsevierStyleCrossRefs" href="#bib0085"><span class="elsevierStyleSup">2,4</span></a> The most common are those based on static models that measure absorbance in the crystal violet (CV) assay and the tetrazolium salt reduction assay (XTT) because of their simplicity and low cost.<a class="elsevierStyleCrossRefs" href="#bib0100"><span class="elsevierStyleSup">5,6</span></a></p><p id="par0015" class="elsevierStylePara elsevierViewall">However, quantitative absorbance values can be converted into qualitative degrees of biofilm production using two different methods. In one, the absorbance values of several strains are organized collectively in ascending order and divided into tertiles, each representing a different degree of biofilm production (low, moderate, and high). In the other, the optical density (OD) of each individual strain is calculated and degrees of biofilm production are established according to the OD of the negative control. To our knowledge, these methods have not been compared across a broad range of <span class="elsevierStyleItalic">Staphylococcus aureus</span> strains. Therefore, our objective was to analyze the concordance between both methods of classifying <span class="elsevierStyleItalic">S. aureus</span> strains in terms of biomass production and the metabolic activity of their biofilm.</p></span><span id="sec0010" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0075">Methods</span><p id="par0020" class="elsevierStylePara elsevierViewall">We selected 233 <span class="elsevierStyleItalic">S. aureus</span> strains isolated from patients with bacteremia and tested them using the CV and XTT assays based on a previous study by our group.<a class="elsevierStyleCrossRef" href="#bib0110"><span class="elsevierStyleSup">7</span></a> Biofilm was formed as described by Peeters et al., with some modifications.<a class="elsevierStyleCrossRef" href="#bib0085"><span class="elsevierStyleSup">2</span></a> Briefly, a loopful of overnight culture of <span class="elsevierStyleItalic">S. aureus</span> was inoculated in 20<span class="elsevierStyleHsp" style=""></span>ml of TSB, which was then incubated overnight with shaking at 30<span class="elsevierStyleHsp" style=""></span>°C in an orbital shaker. After three centrifuge-resuspension cycles with PBS, the pellet was re-suspended in 10<span class="elsevierStyleHsp" style=""></span>ml of TSB. This suspension was adjusted to 0.5 McFarland turbidity using a turbidimeter, and 100<span class="elsevierStyleHsp" style=""></span>μl was inoculated in the 96-well plate and incubated at 37<span class="elsevierStyleHsp" style=""></span>°C for 24<span class="elsevierStyleHsp" style=""></span>h. Planktonic cells were removed by three washes of 100<span class="elsevierStyleHsp" style=""></span>μl of PBS and dried at room temperature before developing CV and XTT assays. Each strain was tested in triplicate, and TSB was used as a negative control. The absorbance was measured at 550<span class="elsevierStyleHsp" style=""></span>nm (CV assay)/492<span class="elsevierStyleHsp" style=""></span>nm (XTT assay) in a spectrophotometer (Biochrom EZ Read 400). Absorbance values for the CV assay were only available in 116 of the 233 strains due to some data loss caused by a computer issue. The cut-offs (based on tertiles) used to classify the strains according to biomass production by CV and metabolic activity by XTT were, respectively, as follows: low, <0.530/<0.214; moderate, 0.530–1.291/0.214–0.416; and high, ≥1.292/≥0.417. Optical density (OD) absorbance values of the strains obtained by CV and XTT were used to classify semi-quantitatively biofilm production according to the method described in Stepanovic et al.<a class="elsevierStyleCrossRef" href="#bib0115"><span class="elsevierStyleSup">8</span></a> Specifically, the cut-off OD (ODc) was defined as three standard deviations above the mean OD of the negative control and strains were classified as follows: OD<span class="elsevierStyleHsp" style=""></span>≤<span class="elsevierStyleHsp" style=""></span>2<span class="elsevierStyleHsp" style=""></span>×<span class="elsevierStyleHsp" style=""></span>ODc<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>weak biofilm producer; 2<span class="elsevierStyleHsp" style=""></span>×<span class="elsevierStyleHsp" style=""></span>ODc<span class="elsevierStyleHsp" style=""></span><<span class="elsevierStyleHsp" style=""></span>OD <<span class="elsevierStyleHsp" style=""></span>4<span class="elsevierStyleHsp" style=""></span>×<span class="elsevierStyleHsp" style=""></span>ODc<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>moderate biofilm producer; and OD<span class="elsevierStyleHsp" style=""></span>≥<span class="elsevierStyleHsp" style=""></span>4<span class="elsevierStyleHsp" style=""></span>×<span class="elsevierStyleHsp" style=""></span>ODc<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>high biofilm producer, respectively.<a class="elsevierStyleCrossRef" href="#bib0120"><span class="elsevierStyleSup">9</span></a></p><p id="par0025" class="elsevierStylePara elsevierViewall">Qualitative variables were expressed as percentages of the number of strains classified in the same group. The agreement between both methods of classification was analyzed using Cohen's kappa coefficient. The kappa statistic values vary from 0 to 1, where 0<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>agreement equivalent to chance, 0.20<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>slight agreement, 0.21–0.40<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>fair agreement, 0.41–0.60<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>moderate agreement, 0.61–0.80<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>substantial agreement, 0.81–0.99<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>near perfect agreement, and 1<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>perfect agreement. The analysis was performed using SPSS software 21.0.</p></span><span id="sec0015" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0080">Results</span><p id="par0030" class="elsevierStylePara elsevierViewall">According to biomass production, 51.7%, 31.9%, and 16.4% were strains classified, respectively, as high, moderate, and low biomass producers using the tertile method. However, for the OD method, 87.1%, 8.6%, and 4.3% were classified as high, moderate, and low biomass producers. In the case of metabolic activity, 31.8%, 38.2%, and 30.1% of strains were classified by the tertile method as having high, moderate, and low metabolic activity. In contrast, 84.1%, 12.4%, and 3.4% were classified as high, moderate, and low metabolic activity by the OD method.</p><p id="par0035" class="elsevierStylePara elsevierViewall">The concordance for biomass production for low, moderate, and high groups was 3.5%, 4.3%, and 50.0%. The concordance for metabolic activity for low, moderate, and high groups was 3.4%, 3.0%, and 30.5%.</p><p id="par0040" class="elsevierStylePara elsevierViewall">The global agreement, defined as the percentage of strains in the same category by both methods—biomass production and metabolic activity—was 57.8% and 36.9% (κ<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>0.180, <span class="elsevierStyleItalic">p</span><span class="elsevierStyleHsp" style=""></span><<span class="elsevierStyleHsp" style=""></span>0.01; and κ<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>0.065, <span class="elsevierStyleItalic">p</span><span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>0.028, respectively) (<a class="elsevierStyleCrossRefs" href="#tbl0005">Tables 1 and 2</a>).</p><elsevierMultimedia ident="tbl0005"></elsevierMultimedia><elsevierMultimedia ident="tbl0010"></elsevierMultimedia><p id="par0045" class="elsevierStylePara elsevierViewall">We found no agreement between the tertile and OD methods for classification of <span class="elsevierStyleItalic">S. aureus</span> strains in terms of biomass production or metabolic activity.</p></span><span id="sec0020" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0085">Discussion</span><p id="par0050" class="elsevierStylePara elsevierViewall"><span class="elsevierStyleItalic">S. aureus</span> is one of the most virulent microorganisms causing device-associated nosocomial infections. This virulence is due to the ability of <span class="elsevierStyleItalic">S. aureus</span> to form biofilm.<a class="elsevierStyleCrossRef" href="#bib0080"><span class="elsevierStyleSup">1</span></a></p><p id="par0055" class="elsevierStylePara elsevierViewall">Over the years, several in vitro models have been developed to study biofilm formation. The static 96-well plate model is the most frequently used because of its low cost and simplicity.<a class="elsevierStyleCrossRefs" href="#bib0115"><span class="elsevierStyleSup">8,10</span></a> However, despite the study carried out by Stepanovic et al., which showed that the classification by OD values was the most widely used for biofilm formation in bacterial biofilms,<a class="elsevierStyleCrossRef" href="#bib0115"><span class="elsevierStyleSup">8</span></a> classification of biofilm formation into qualitative degrees remains controversial, as individual laboratories use the most suitable one for their research.<a class="elsevierStyleCrossRefs" href="#bib0130"><span class="elsevierStyleSup">11–12</span></a></p><p id="par0060" class="elsevierStylePara elsevierViewall">Different conclusions have been reached in clinical studies assessing the impact of biofilm production using degrees of biofilm production according to patient outcome.</p><p id="par0065" class="elsevierStylePara elsevierViewall">Muñoz et al., reported that biofilm was not a predictor of mortality or unfavorable prognosis in adults with candidemia when biofilm production was classified by tertile.<a class="elsevierStyleCrossRefs" href="#bib0140"><span class="elsevierStyleSup">13,14</span></a> Rajendran et al., in contrast, reported that candidemia and biofilm production were significantly associated with <span class="elsevierStyleItalic">C. albicans</span> mortality in 15.6% of their study population (217 patients).<a class="elsevierStyleCrossRef" href="#bib0150"><span class="elsevierStyleSup">15</span></a> Therefore, the different results from various studies may be due to the fact that the authors have classified the strains using different parameters for biofilm production. Moreover, Guembe et al., found that biofilm production in 485 patients with <span class="elsevierStyleItalic">S. aureus</span> bacteremia was not associated with poor outcome. The results may have been different if the OD method had been used to classify strains in terms of biofilm production.<a class="elsevierStyleCrossRefs" href="#bib0110"><span class="elsevierStyleSup">7,13–15</span></a></p><p id="par0070" class="elsevierStylePara elsevierViewall">The main limitation of the study is that concordance between methods to classify <span class="elsevierStyleItalic">S. aureus</span> biofilm production was only tested using CV and XTT, and data can not be extrapolated to other biofilm production methods, such as MBEC assay or CDC Bioreactor.</p></span><span id="sec0025" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0090">Conclusion</span><p id="par0075" class="elsevierStylePara elsevierViewall">For this reason, we compared the two main methods for biofilm classification and found no concordance between biomass production and metabolic activity, thus demonstrating the importance of establishing a unique standard method that can be widely used to compare results between laboratories.</p><p id="par0080" class="elsevierStylePara elsevierViewall">We consider that calculating the OD of each strain individually and comparing it against the OD of the negative control (OD method) seems the most reliable method for biofilm classification, as it can be used independently of the number of strains.</p></span><span id="sec0030" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0095">Availability of data and materials</span><p id="par0085" class="elsevierStylePara elsevierViewall">The original datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.</p></span><span id="sec0035" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0100">Authors’ contributions</span><p id="par0090" class="elsevierStylePara elsevierViewall">MCL, BA, CC-S and MG contributed in the conception and design of the study and had full access to all of the study data. MCL, BA, AS and RC made substantial contributions to acquisition, analysis, and interpretation of data. PM, MCL, BA and MG contributed substantially to the study design, data analysis and interpretation, and the writing of the manuscript. MG contributed to the conception and design of the study and data analysis and interpretation and was involved in drafting the manuscript and critically reviewing it for important intellectual content. She takes responsibility for the integrity of the data and the accuracy of the data analysis. All authors read and approved the final manuscript.</p></span><span id="sec0040" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0105">Ethics approval</span><p id="par0095" class="elsevierStylePara elsevierViewall">The study was approved by the Ethics Committee of Hospital Gregorio Marañón.</p></span><span id="sec0045" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0110">Consent for publication</span><p id="par0100" class="elsevierStylePara elsevierViewall">Not applicable.</p></span><span id="sec0050" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0115">Financial support</span><p id="par0105" class="elsevierStylePara elsevierViewall">M. Guembe is supported by the Miguel Servet Program (ISCIII-MICINN, MS13/00268) of the health Research Fund (FIS, PI18/00045) of the Carlos III Health Institute (ISCIII), Madrid, Spain. MC. Latorre is supported by the Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid y Fondo Social Europeo (PEJD-2017-PRE/BMD-3596). Beatriz Alonso was supported by the Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid y Fondo Social Europeo (PEJ15/BIO/AI-0406). The study was partially financed by grants from the European Regional Development Fund (<span class="elsevierStyleGrantSponsor" id="gs1">FEDER</span>) “A way of making Europe”.</p></span><span id="sec0055" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0120">Conflicts of interest</span><p id="par0110" class="elsevierStylePara elsevierViewall">The authors declare that they have no conflicts of interest.</p></span></span>" "textoCompletoSecciones" => array:1 [ "secciones" => array:18 [ 0 => array:3 [ "identificador" => "xres1674898" "titulo" => "Abstract" "secciones" => array:4 [ 0 => array:2 [ "identificador" => "abst0005" "titulo" => "Introduction" ] 1 => array:2 [ "identificador" => "abst0010" "titulo" => "Methods" ] 2 => array:2 [ "identificador" => "abst0015" "titulo" => "Results" ] 3 => array:2 [ "identificador" => "abst0020" "titulo" => "Conclusions" ] ] ] 1 => array:2 [ "identificador" => "xpalclavsec1486059" "titulo" => "Keywords" ] 2 => array:2 [ "identificador" => "xpalclavsec1486061" "titulo" => "Abbreviation" ] 3 => array:3 [ "identificador" => "xres1674899" "titulo" => "Resumen" "secciones" => array:4 [ 0 => array:2 [ "identificador" => "abst0025" "titulo" => "Introducción" ] 1 => array:2 [ "identificador" => "abst0030" "titulo" => "Métodos" ] 2 => array:2 [ "identificador" => "abst0035" "titulo" => "Resultados" ] 3 => array:2 [ "identificador" => "abst0040" "titulo" => "Conclusiones" ] ] ] 4 => array:2 [ "identificador" => "xpalclavsec1486060" "titulo" => "Palabras clave" ] 5 => array:2 [ "identificador" => "sec0005" "titulo" => "Introduction" ] 6 => array:2 [ "identificador" => "sec0010" "titulo" => "Methods" ] 7 => array:2 [ "identificador" => "sec0015" "titulo" => "Results" ] 8 => array:2 [ "identificador" => "sec0020" "titulo" => "Discussion" ] 9 => array:2 [ "identificador" => "sec0025" "titulo" => "Conclusion" ] 10 => array:2 [ "identificador" => "sec0030" "titulo" => "Availability of data and materials" ] 11 => array:2 [ "identificador" => "sec0035" "titulo" => "Authors’ contributions" ] 12 => array:2 [ "identificador" => "sec0040" "titulo" => "Ethics approval" ] 13 => array:2 [ "identificador" => "sec0045" "titulo" => "Consent for publication" ] 14 => array:2 [ "identificador" => "sec0050" "titulo" => "Financial support" ] 15 => array:2 [ "identificador" => "sec0055" "titulo" => "Conflicts of interest" ] 16 => array:2 [ "identificador" => "xack590038" "titulo" => "Acknowledgements" ] 17 => array:1 [ "titulo" => "References" ] ] ] "pdfFichero" => "main.pdf" "tienePdf" => true "fechaRecibido" => "2020-07-17" "fechaAceptado" => "2020-11-01" "PalabrasClave" => array:2 [ "en" => array:2 [ 0 => array:4 [ "clase" => "keyword" "titulo" => "Keywords" "identificador" => "xpalclavsec1486059" "palabras" => array:5 [ 0 => "Biofilm" 1 => "Methods" 2 => "Crystal violet assay" 3 => "XTT" 4 => "<span class="elsevierStyleItalic">Staphylococcus aureus</span>" ] ] 1 => array:4 [ "clase" => "abr" "titulo" => "Abbreviation" "identificador" => "xpalclavsec1486061" "palabras" => array:4 [ 0 => "<span class="elsevierStyleItalic">S. aureus</span>" 1 => "CV" 2 => "XTT" 3 => "OD" ] ] ] "es" => array:1 [ 0 => array:4 [ "clase" => "keyword" "titulo" => "Palabras clave" "identificador" => "xpalclavsec1486060" "palabras" => array:5 [ 0 => "Biopelícula" 1 => "Métodos" 2 => "Ensayo cristal violeta" 3 => "XTT" 4 => "<span class="elsevierStyleItalic">Staphylococcus aureus</span>" ] ] ] ] "tieneResumen" => true "resumen" => array:2 [ "en" => array:3 [ "titulo" => "Abstract" "resumen" => "<span id="abst0005" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0010">Introduction</span><p id="spar0005" class="elsevierStyleSimplePara elsevierViewall">Strains can be classified in terms of biofilm production from quantitative absorbance values collectively by dividing strains into tertile ranks or individually by calculating the optical density for the negative control. However, these methods have not been compared in a large sample of <span class="elsevierStyleItalic">Staphylococcus aureus</span> strains. Therefore, our objective was to analyze the agreement between both methods in terms of biomass production and metabolic activity of their biofilm.</p></span> <span id="abst0010" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0015">Methods</span><p id="spar0010" class="elsevierStyleSimplePara elsevierViewall">We classified 233 <span class="elsevierStyleItalic">S. aureus</span> strains by biomass production and metabolic activity using the crystal violet and XTT assays, respectively. Strains were classified as low, moderate, or high biofilm producers according to tertile or optical density.</p></span> <span id="abst0015" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0020">Results</span><p id="spar0015" class="elsevierStyleSimplePara elsevierViewall">We found no agreement between both methods (<span class="elsevierStyleItalic">p</span><span class="elsevierStyleHsp" style=""></span><<span class="elsevierStyleHsp" style=""></span>0.001 and <span class="elsevierStyleItalic">p</span><span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>0.028, respectively).</p></span> <span id="abst0020" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0025">Conclusions</span><p id="spar0020" class="elsevierStyleSimplePara elsevierViewall">We consider strains’ biofilm classification by optical density to be a more reliable method, as it depends on the individual absorbance of each strain.</p></span>" "secciones" => array:4 [ 0 => array:2 [ "identificador" => "abst0005" "titulo" => "Introduction" ] 1 => array:2 [ "identificador" => "abst0010" "titulo" => "Methods" ] 2 => array:2 [ "identificador" => "abst0015" "titulo" => "Results" ] 3 => array:2 [ "identificador" => "abst0020" "titulo" => "Conclusions" ] ] ] "es" => array:3 [ "titulo" => "Resumen" "resumen" => "<span id="abst0025" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0035">Introducción</span><p id="spar0025" class="elsevierStyleSimplePara elsevierViewall">Las cepas se pueden clasificar en términos de producción de biopelícula a partir de valores cuantitativos de absorbancia dividiendo de forma colectiva las cepas en rangos por terciles o individualmente calculando la densidad óptica para el control negativo. Sin embargo, estos métodos no se han comparado en una gran muestra de cepas de <span class="elsevierStyleItalic">Staphylococcus aureus</span>. Por lo tanto, nuestro objetivo fue analizar la concordancia entre ambos métodos en términos de producción de biomasa y actividad metabólica de la biopelícula.</p></span> <span id="abst0030" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0040">Métodos</span><p id="spar0030" class="elsevierStyleSimplePara elsevierViewall">Se clasificaron 233 cepas de <span class="elsevierStyleItalic">S. aureus</span> por producción de biomasa y actividad metabólica utilizando los ensayos de cristal violeta y de XTT, respectivamente. Las cepas se clasificaron como altamente, moderadamente o bajamente productoras de biopelícula según terciles o densidad óptica.</p></span> <span id="abst0035" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0045">Resultados</span><p id="spar0035" class="elsevierStyleSimplePara elsevierViewall">No encontramos concordancias entre ambos métodos (p<span class="elsevierStyleHsp" style=""></span><<span class="elsevierStyleHsp" style=""></span>0,001 y p<span class="elsevierStyleHsp" style=""></span>=<span class="elsevierStyleHsp" style=""></span>0,028, respectivamente).</p></span> <span id="abst0040" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0050">Conclusiones</span><p id="spar0040" class="elsevierStyleSimplePara elsevierViewall">Consideramos que la clasificación del <span class="elsevierStyleItalic">biofilm</span> de cepas por densidad óptica es un método más fiable, ya que depende de la absorción individual de cada cepa.</p></span>" "secciones" => array:4 [ 0 => array:2 [ "identificador" => "abst0025" "titulo" => "Introducción" ] 1 => array:2 [ "identificador" => "abst0030" "titulo" => "Métodos" ] 2 => array:2 [ "identificador" => "abst0035" "titulo" => "Resultados" ] 3 => array:2 [ "identificador" => "abst0040" "titulo" => "Conclusiones" ] ] ] ] "multimedia" => array:2 [ 0 => array:8 [ "identificador" => "tbl0005" "etiqueta" => "Table 1" "tipo" => "MULTIMEDIATABLA" "mostrarFloat" => true "mostrarDisplay" => false "detalles" => array:1 [ 0 => array:3 [ "identificador" => "at1" "detalle" => "Table " "rol" => "short" ] ] "tabla" => array:2 [ "leyenda" => "<p id="spar0050" class="elsevierStyleSimplePara elsevierViewall">OD, optical density; CV, crystal violet assay.</p>" "tablatextoimagen" => array:1 [ 0 => array:2 [ "tabla" => array:1 [ 0 => """ <table border="0" frame="\n \t\t\t\t\tvoid\n \t\t\t\t" class=""><thead title="thead"><tr title="table-row"><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col"> \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " colspan="5" align="center" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black">Tertile method, <span class="elsevierStyleItalic">N</span> (%)</th></tr><tr title="table-row"><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black"> \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black"> \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black">Low \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black">Moderate \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black">High \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black">Total \t\t\t\t\t\t\n \t\t\t\t\t\t</th></tr></thead><tbody title="tbody"><tr title="table-row"><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " rowspan="4" align="left" valign="middle">OD method, <span class="elsevierStyleItalic">N</span> (%)</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t">Low \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t"><span class="elsevierStyleBold">4 (3.5)</span> \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">1 (0.9) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">0 (0.0) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">5 (4.3) \t\t\t\t\t\t\n \t\t\t\t</td></tr><tr title="table-row"><td class="td-with-role" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t ; entry_with_role_rowhead " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t">Moderate \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">3 (2.6) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t"><span class="elsevierStyleBold">5 (4.3)</span> \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">2 (1.7) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">10 (8.6) \t\t\t\t\t\t\n \t\t\t\t</td></tr><tr title="table-row"><td class="td-with-role" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t ; entry_with_role_rowhead " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t">High \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">12 (10.3) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">31 (26.7) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t"><span class="elsevierStyleBold">58 (50.0)</span> \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">101 (87.1) \t\t\t\t\t\t\n \t\t\t\t</td></tr><tr title="table-row"><td class="td-with-role" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t ; entry_with_role_rowhead " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t">Total \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">19 (16.4) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">37 (31.8) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">60 (51.7) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t"><span class="elsevierStyleBold">116</span> \t\t\t\t\t\t\n \t\t\t\t</td></tr></tbody></table> """ ] "imagenFichero" => array:1 [ 0 => "xTab2849566.png" ] ] ] ] "descripcion" => array:1 [ "en" => "<p id="spar0045" class="elsevierStyleSimplePara elsevierViewall">Concordance between tertile and OD methods for classification of <span class="elsevierStyleItalic">S. aureus</span> strains in terms of biomass production by the CV method.</p>" ] ] 1 => array:8 [ "identificador" => "tbl0010" "etiqueta" => "Table 2" "tipo" => "MULTIMEDIATABLA" "mostrarFloat" => true "mostrarDisplay" => false "detalles" => array:1 [ 0 => array:3 [ "identificador" => "at2" "detalle" => "Table " "rol" => "short" ] ] "tabla" => array:2 [ "leyenda" => "<p id="spar0060" class="elsevierStyleSimplePara elsevierViewall">OD, optical density; XTT, tetrazolium salt assay.</p>" "tablatextoimagen" => array:1 [ 0 => array:2 [ "tabla" => array:1 [ 0 => """ <table border="0" frame="\n \t\t\t\t\tvoid\n \t\t\t\t" class=""><thead title="thead"><tr title="table-row"><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col"> \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " colspan="5" align="center" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black">Tertile method, <span class="elsevierStyleItalic">N</span> (%)</th></tr><tr title="table-row"><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black"> \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black"> \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black">Low \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black">Moderate \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black">High \t\t\t\t\t\t\n \t\t\t\t\t\t</th><th class="td" title="\n \t\t\t\t\ttable-head\n \t\t\t\t " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t" scope="col" style="border-bottom: 2px solid black">Total \t\t\t\t\t\t\n \t\t\t\t\t\t</th></tr></thead><tbody title="tbody"><tr title="table-row"><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " rowspan="4" align="left" valign="middle">OD method, <span class="elsevierStyleItalic">N</span> (%)</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t">Low \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t"><span class="elsevierStyleBold">8 (3.4)</span> \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">0 (0.0) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">0 (0.0) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">8 (3.4) \t\t\t\t\t\t\n \t\t\t\t</td></tr><tr title="table-row"><td class="td-with-role" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t ; entry_with_role_rowhead " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t">Moderate \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">19 (8.2) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t"><span class="elsevierStyleBold">7 (3.0)</span> \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">3 (1.3) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">29 (12.5) \t\t\t\t\t\t\n \t\t\t\t</td></tr><tr title="table-row"><td class="td-with-role" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t ; entry_with_role_rowhead " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t">High \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">43 (18.5) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">82 (35.2) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t"><span class="elsevierStyleBold">71 (30.5)</span> \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">196 (84.1) \t\t\t\t\t\t\n \t\t\t\t</td></tr><tr title="table-row"><td class="td-with-role" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t ; entry_with_role_rowhead " align="left" valign="\n \t\t\t\t\ttop\n \t\t\t\t">Total \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">70 (30.0) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">89 (38.2) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t">74 (31.8) \t\t\t\t\t\t\n \t\t\t\t</td><td class="td" title="\n \t\t\t\t\ttable-entry\n \t\t\t\t " align="char" valign="\n \t\t\t\t\ttop\n \t\t\t\t"><span class="elsevierStyleBold">233</span> \t\t\t\t\t\t\n \t\t\t\t</td></tr></tbody></table> """ ] "imagenFichero" => array:1 [ 0 => "xTab2849567.png" ] ] ] ] "descripcion" => array:1 [ "en" => "<p id="spar0055" class="elsevierStyleSimplePara elsevierViewall">Concordance between tertile and OD methods for classification of <span class="elsevierStyleItalic">S. aureus</span> strains in terms of metabolic activity by the XTT assay.</p>" ] ] ] "bibliografia" => array:2 [ "titulo" => "References" "seccion" => array:1 [ 0 => array:2 [ "identificador" => "bibs0015" "bibliografiaReferencia" => array:15 [ 0 => array:3 [ "identificador" => "bib0080" "etiqueta" => "1" "referencia" => array:1 [ 0 => array:2 [ "contribucion" => array:1 [ 0 => array:2 [ "titulo" => "A personal history of research on microbial biofilms and biofilm infections" "autores" => array:1 [ 0 => array:2 [ "etal" => false "autores" => array:1 [ 0 => "N. 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Journal Information
Brief report
The classification of Staphylococcus aureus strains by biofilm production differs depending on the method used
La clasificación de cepas de Staphylococcus aureus según la producción de biopelícula varía dependiendo del método utilizado
María Consuelo Latorrea,b, Beatriz Alonsoa,b, Raquel Crucesa,b, Aurora Sanzc, Patricia Muñoza,b,d,e, María Guembea,b,
Corresponding author
a Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañon, Madrid, Spain
b Instituto de Investigación Sanitaria Gregorio Marañon, Madrid, Spain
c School of Biology, Universidad Complutense de Madrid, Madrid, Spain
d Medicine Department, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain
e CIBER Enfermedades Respiratorias-CIBERES, Madrid, Spain