Frozen Elephant Trunk procedure for Acute type A Aortic Dissection: analysis of distal aortic remodeling according to the Society for Vascular Surgery (SVS)/Society of Thoracic Surgeons (STS) reporting standard.

OBJECTIVE: To investigate impact of Frozen Elephant Trunk (FET) on long-term distal aortic remodelling in acute AAD according to the latest recommended standards from the Society for Vascular Surgery (SVS)/Society of Thoracic Surgeons (STS). METHODS: Clinical data and imaging of patients undergone FET to treat acute AAD over the last 8 years were retrospectively reviewed. Patients were included if a pre- and post-operative Computed AngioTomographies at least 30-day from surgery was available for comparison. Contrasted postprocessed imaging were analysed with Aquarius iNtuition (TeraRecon Inc., Foster City, CA, USA) to analyse long-term positive aortic remodelling, FL thrombosis and aortic expansion according to the SVS/STS recommendations. Secondary endpoints were the rate of in-hospital and long-term mortality, spinal cord ischaemia and aortic-related reinterventions. RESULTS: Out of 75 patients who underwent FET for type A AAD, n=41(54.6%) were included. Significant positive aortic remodelling was reported in Ishimaru zone 1-4 but not in visceral/infrarenal aorta (p<0.001) and overall rate of FL thrombosis was 95.1% (n=39). Aortic expansion rates were: 4.9% in zones 1-4, 8.3% in zones 5-6 and 15% in zone 7. The rates of in-hospital mortality and long-term mortality were 7.3% (n=3) and 9.7% (n=4) respectively. At a median follow-up of 11 months (range 1-141, reintervention rate was 17.1%. CONCLUSIONS: We report positive aortic remodelling of the distal thoracic aorta in patients who underwent FET for acute AAD according to the SVS/STS reporting standards. The positive effect on the distal aorta is limited to the thoracic segments but not in the visceral aorta.

Relationship between human activities and environmental changes in the southern Tibetan Plateau since the Little Ice Age.

The Tibetan Plateau (TP) is one of the most challenging areas for human long-term settlement due to its extreme living environment. Understanding the relationship between human activities and environmental changes in this extreme environment is important and can provide a historical reference for adapting to future climate change. In this study, we took the Angren Basin in the southern TP as a case study to elucidate the relationship since Little Ice Age (LIA). Using fecal stanol in feces, lake and river surface sediments, surface soils, and sediment core, we found that specific indices S1 and S2 from the composition of coprostanol, epicoprostanol, 5ß-ethylcoprostanol and 5ß-ethylepicoprostanol can reflect changes in human population and herbivores, respectively. Through the comparison between environmental changes determined by grain size, elements, sedimentation rate, and other climate records, the relationship between human activities and environmental changes was interpreted. Our results indicate that: (i) during 1480-1820 CE, the fecal stanols in lake sediments mainly originated from livestock, and the human population was low. In contrast, during 1820-2021 CE, the proportion and flux of S1 have been continuously increasing, indicating significant population growth. (ii) During the middle LIA, the cold-dry climate inhibited the development of agriculture and farming. However, the increased precipitation during the late LIA promoted that development, resulting in an increase in human population and livestock in a short term. (iii) Since 1951, people have reclaimed wasteland and developed husbandry, leading to increased soil erosion. (iv) Over the past 40 years, with a warm-humid climate and good policy support, human activities, such as agriculture and husbandry, have rapidly increased, but soil erosion has declined in the recent 20 years due to good soil-water conservation efforts. This study sheds light on the relationship between human activities and environmental changes and provides insights into future climate change responses.

Inflammation in aortic surgery: postoperative evolution of biomarkers according pathologies and segments of the aorta.

OBJECTIVES: Aortic pathologies often present with elevated inflammatory biomarkers due to the nature of the disease. Open aortic surgery causes significant trauma to the body due to often mandatory ischemic periods, long cardiopulmonary bypass times and polytransfusion. We aim to determine postoperative trends on inflammation biomarkers for different aortic pathologies and type of surgery in different segments of the aorta. METHODS: Retrospective review of prospectively collected data of 193 consecutive patients who underwent aortic surgery in our centre between 2017 and 2021, grouped according to the type of aortic intervention: (1) Type A aortic dissection (AD) repair with ascending aorta/hemiarch replacement, (2) Aortic root replacement (ARR), (3) Aortic arch + Frozen elephant trunk (FET), (4) Descending thoracic aorta (DTA)/Thoraco-Abdominal aortic repair (TAA). Primary outcomes were daily values of white blood cells (WBC) and C-Reactive Protein (CRP) during the first 15 postoperative days. RESULTS: All groups had a similar inflammatory peak in the first 2-4 days (WBC 12-15 × 109 c/L). AD and FET groups show similar trends with WBC and CRP peaks on days 2 and 10. The ARR group didn't experience the 2nd peak as most patients were already discharged. DTA/TAA patients experienced a more prolonged inflammatory response, reaching a plateau by day 5-10. AD group shows the highest WBC levels and the DTA/TAAA group the highest CRP levels. CRP levels remain elevated (100-200 mg/L) in all groups after 15 postoperative days. CONCLUSIONS: Inflammatory biomarkers show different postoperative trends depending on the clinical presentation and complexity of the aortic procedure performed. Further understanding of the inflammatory response to different aortic pathologies and surgical procedures will permit reduction on the liberal use of antibiotics that this cohort of patients are usually exposed to. An earlier version of the data included in this manuscript was presented as Oral Abstract in the UK Society of Cardiothoracic Surgery Annual meeting in 2021.

Effectiveness of a Peer Mentoring on University Dropout and Academic Performance / La eficacia de un programa de mentoría en el abandono y el rendimiento académico

Mentoring programs have been proposed to reduce dropout and increase academic performance. We analyzed the effect of peer mentoring on university dropout and academic performance in the context of Spain. We applied a quasi-experimental posttest-only control group design with 3,774 students (mentees, n = 1,887; control, n = 1,887). Mentees had participated in a peer mentoring program. We apply the student’s t-test, Cohen’s d, phi statistic, and chi-square statistic. Mentees exhibited lower dropout than controls and showed higher academic performance regardless of the area of knowledge. Results support the implementation of mentoring programs in Spanish universities with the goal of reducing student dropout and increasing academic performance. The research provides empirical evidence for theory building in higher education studies, developmental relationships, and integration programs. (AU)

Se ha propuesto la aplicación de programas de mentoría para reducir la deserción universitaria y aumentar el rendimiento académico. En el artículo analizamos el efecto de la mentoría entre pares sobre el abandono universitario y el rendimiento académico en España. Aplicamos un diseño de grupo de control cuasiexperimental con medida post en una muestra de 3.774 estudiantes (mentorados, n = 1,887; control, n = 1,887). Los mentorados habían participado en un programa de mentoría entre pares. Aplicamos la prueba t de Student, la d de Cohen, el estadístico phi y el chi-cuadrado. Los mentorados presentaban un menor abandono que los controles y un mayor rendimiento académico independientemente del área de conocimiento. Los resultados avalan la implementación de programas de mentoría en las universidades españolas con el objetivo de reducir el abandono universitario y aumentar el rendimiento académico. La investigación proporciona evidencia empírica para la elaboración de teorías en estudios de educación superior, relaciones de desarrollo y programas de integración. (AU)

Schwannoma and Post-vaccine Changes: A Case Report.

Schwannomas are benign sheaths of Schwann cells that can present with degenerative and morphological changes; necrosis or hemorrhage are rare findings in these tumors. We present the case of a 28-year-old man with a C2-C4 cervical Schwannoma who experienced upper limb paresthesia in 2020 while presenting with COVID-19 symptoms. The patient later recovered and came to our institution, where surgery was scheduled one year after the initial diagnosis. One week before surgery, the patient received the first dose of the Moderna vaccine. Despite being asymptomatic, the patient underwent successful total resection of the schwannoma, which was confirmed histologically. However, extensive necrosis with abundant foamy macrophages was observed, suggesting a possible link to post-vaccine effects.

Índice neutrófilo linfocito como predictor de infección del sitio quirúrgico en cirugía abdominal urgente

Introducción: Las infecciones del sitio quirúrgico representan una carga significativa en relación con la morbilidad, la mortalidad y costos adicionales. Por lo tanto, la prevención es importante. Objetivo: Comparar el índice neutrófilos-linfocitos con la escala SENIC para predecir infección del sitio quirúrgico en pacientes que sufrieron una cirugía abdominal de urgencia. Materiales y Métodos: Estudio transversal analítico, realizado en el Hospital de Alta Especialidad de Veracruz en expedientes de pacientes post-operados de urgencia, valorándose la escala SENIC (que incluye tipo de cirugía, duración del procedimiento, grado de asepsia de la intervención y 3 o más diagnósticos posoperatorios) y el índice neutrófilos-linfocitos (definido como la razón neutrófilos sobre linfocitos). Resultados: La edad promedio de los pacientes fue de 47,7 ± 18,7 años, con un predominio del sexo masculino 83 (62%), la estancia hospitalaria media fue de 29,7 ± 14,7 días, los procedimientos fueron la laparotomía exploradora en 57 (42,2%) y la apendicectomía en 26 (19,2%). Se aisló Escherichia coli en 27 (30%). Se obtuvo una sensibilidad de 69% y especificidad de 58% para el índice neutrófilos-linfocitos y para SENIC una sensibilidad 45% y una especificidad de 73%. Las estadísticas C para el índice neutrófilos-linfocitos y SENIC fueron 0,603 (IC: 0,524 − 0,682) y 0,668 (IC 95%: 0,588 − 0,749), respectivamente. Discusión y Conclusión: Ambos métodos muestran una precisión predictiva similar para infección del sitio quirúrgico, si bien calcular el índice neutrófiloslinfocitos es mucho más rápido y sencillo.

Introduction: Surgical site infections represent a significant burden in relation to morbidity, mortality, and additional costs. Therefore, prevention is important. Objective: To compare the neutrophil-lymphocyte index with the SENIC scale to predict surgical site infection in patients who underwent emergency abdominal surgery. Materials and Methods: Analytical cross-sectional study, carried out at the Hospital de Alta Especialidad de Veracruz in records of emergency post-operative patients, evaluating the SENIC scale (which includes type of surgery, duration of the procedure, degree of asepsis of the intervention and 3 or more postoperative diagnoses) and the neutrophil-to-lymphocyte ratio (defined as the ratio of neutrophils to lymphocytes). Results: The average age of the patients was 47.7 ± 18.7 years, with a predominance of males 83 (62%); the mean hospital stay was 29.7 ± 14.7 days, the procedures were exploratory laparotomy in 57 (42.2%) and appendectomy in 26 (19.2%). Escherichia coli was isolated in 27 (30%). A sensitivity of 69% and specificity of 58% was obtained for the neutrophil-lymphocyte index and for SENIC a sensitivity of 45% and a specificity of 73%. The C statistics for the neutrophil-lymphocyte ratio and SENIC were 0.603 (CI: 0.524 − 0.682) and 0.668 (95% CI: 0.588 − 0.749), respectively. Discussion and Conclusion: Both methods show similar predictive accuracy for surgical site infection, although calculating the neutrophil-lymphocyte ratio is much faster and easier.

An exploratory cost-effectiveness analysis of a novel tissue valve compared with mechanical valves for surgical aortic valve replacement in subgroups of people aged 55-64 and 65+ with aortic stenosis in the UK.

OBJECTIVE: Exploratory analysis to conceptualize and evaluate the potential cost-effectiveness and economic drivers of using a novel tissue valve compared with mechanical heart valves for surgical aortic valve replacement (SAVR) in people aged 55-64 and 65+ with aortic stenosis (AS) from a National Health Service (NHS) UK perspective. METHODS: A decision-analytic model was developed using a partitioned survival model. Parameter inputs were obtained from published literature. Deterministic and probabilistic sensitivity analyses (DSA and PSA) were conducted to explore the uncertainty around the parameters. RESULTS: The novel tissue valve was potentially associated with higher quality-adjusted life years (QALYs) of 0.01 per person. Potential cost savings were greatest for those aged 55-64 (£408) versus those aged 65+(£53). DSA indicated the results to be most dependent on relative differences in general mortality, procedure costs, and reoperation rates. PSA estimated around 75% of the iterations to be cost-effective at £20,000 per QALY for those aged 55-64, and 57% for those aged 65+. CONCLUSIONS: The exploratory analysis suggests that the novel tissue valve could be a cost-effective intervention for people over the age of 55 with AS who are suitable for SAVR in the UK.

Polar Heterobenzylic C(sp3)-H Chlorination Pathway Enabling Efficient Diversification of Aromatic Nitrogen Heterocycles.

Site-selective radical reactions of benzylic C-H bonds are now highly effective methods for C(sp3-H) functionalization and cross-coupling. The existing methods, however, are often ineffective with heterobenzylic C-H bonds in alkyl-substituted pyridines and related aromatic heterocycles that are prominently featured in pharmaceuticals and agrochemicals. Here, we report new synthetic methods that leverage polar, rather than radical, reaction pathways to enable the selective heterobenzylic C-H chlorination of 2- and 4-alkyl-substituted pyridines and other heterocycles. Catalytic activation of the substrate with trifluoromethanesulfonyl chloride promotes the formation of enamine tautomers that react readily with electrophilic chlorination reagents. The resulting heterobenzyl chlorides can be used without isolation or purification in nucleophilic coupling reactions. This chlorination-diversification sequence provides an efficient strategy to achieve heterobenzylic C-H cross-coupling with aliphatic amines and a diverse collection of azoles, among other coupling partners.

Managing the Root in Acute Type A Aortic Dissections: Are We Ready for a Standardized Approach?

OBJECTIVES: Surgical repair of Type A aortic dissection (TAAD) requires exclusion of the primary entry tear and reestablishment of flow into the distal true lumen. Provided that the majority of tears occur within the ascending aorta (AA), replacing only that segment seems a safe option; however, this strategy leaves the root susceptible to dilatation and need for reintervention. We aimed to review the outcomes of the two strategies: aortic root replacement (ARR) and isolated ascending aortic replacement. METHODS: Retrospective analysis of prospectively collected data for all consecutive patients who underwent repair of acute TAAD at our institution from 2015 to 2020 was conducted. Patients were divided into two groups: (1) ARR and (2) isolated AA replacement as index operation for TAAD repair. Primary outcomes were mortality and need for reintervention during the follow-up. RESULTS: A total of 194 patients were included in the study; 68 (35%) in the ARR group and 126 (65%) in the AA group. There were no significant differences in postoperative complications or in-hospital mortality (23%; p = 0.51) between groups. Seven patients (4.7%) died during follow-up and eight patients underwent aortic reinterventions, including proximal aortic segments (two patients) and distal procedures (six patients). CONCLUSION: Both aortic root and AA replacement are acceptable and safe techniques. The growth of an untouched root is slow, and reintervention in this aortic segment is infrequent compared with distal aortic segments, hence preserving the root could be an option for older patients provided that there is no primary tear within the root.

Open descending and thoracoabdominal aortic replacement: operative steps for patients with prior endovascular treatment.

Open surgery remains the gold standard for the treatment of the thoracoabdominal aorta. The rising number of endovascularly treated patients comes with an increase in the number of patients who require secondary open interventions due to the complex nature of the aortic disease or to treat endovascular complications. We describe our current approach to secondary open extent II thoracoabdominal aortic repair in patients with prior endovascular repair. In this case report, we show two different cases that exemplify this scenario.

Thoracoabdominal Aneurysm Repair During Early Stage of Pregnancy: Can and Should We Save the Baby?

Aortic dissection during pregnancy is a life-threatening condition for both mother and fetus. We present the case of a 34-year-old woman with a rapidly expanding abdominal aorta in the context of a chronic type B aortic dissection. A 4 to 6 weeks' viable pregnancy was incidentally diagnosed during the preoperative workup. She underwent urgent extent II thoracoabdominal aortic aneurysm repair with left-sided heart bypass. Postoperatively, vaginal ultrasound evaluation confirmed viability of the fetus, but the patient wished to terminate the pregnancy because of the possible unknown hypoxic effects on the fetus.

Effect of COVID-19 on outpatient services in patients with aortovascular disease: a UK multicentre study.

INTRODUCTION: The SARS-CoV-2 coronavirus disease 2019 (COVID-19) pandemic has disrupted healthcare services worldwide. Outpatient services have necessarily been restructured to accommodate COVID-19 patients and to maintain social distancing measures. The aim of our study was to investigate how the COVID-19 pandemic has affected outpatient healthcare provision for patients with aortovascular disease. METHODS: In this prospective study, a standardised proforma was circulated to seven aortic centres in the UK. Data on outpatient encounters were collected from March to July 2020. Captured data included demographic details, disease pattern, type of encounter (face-to-face, video or telephone), clinic outcome and availability of imaging. RESULTS: A total of 632 patients were included in the study, including 164 (25.9%) new referrals. In this cohort, clinic settings have shifted towards remote consultations, with 424 (67.1%) patients undergoing telephone appointments. Over a third of new patients (34.8%) had a delay in diagnostic tests, which might be attributable to the indirect effects of COVID-19. A total of 102 (16.1%) patients were added to a surgical waiting list following clinic. CONCLUSIONS: To the best of our knowledge, this is the largest study of outpatient activity during the COVID-19 pandemic in patients with aortovascular disease. We demonstrate how the speciality has adapted to accommodate government-endorsed changes in healthcare provision, and question how COVID-19 may have affected access to diagnostics. Finally, we discuss how COVID-19 will affect patients added to surgical waiting lists.

Consistent centennial-scale change in European sub-Arctic peatland vegetation toward Sphagnum dominance-Implications for carbon sink capacity.

Climate warming is leading to permafrost thaw in northern peatlands, and current predictions suggest that thawing will drive greater surface wetness and an increase in methane emissions. Hydrology largely drives peatland vegetation composition, which is a key element in peatland functioning and thus in carbon dynamics. These processes are expected to change. Peatland carbon accumulation is determined by the balance between plant production and peat decomposition. But both processes are expected to accelerate in northern peatlands due to warming, leading to uncertainty in future peatland carbon budgets. Here, we compile a dataset of vegetation changes and apparent carbon accumulation data reconstructed from 33 peat cores collected from 16 sub-arctic peatlands in Fennoscandia and European Russia. The data cover the past two millennia that has undergone prominent changes in climate and a notable increase in annual temperatures toward present times. We show a pattern where European sub-Arctic peatland microhabitats have undergone a habitat change where currently drier habitats dominated by Sphagnum mosses replaced wetter sedge-dominated vegetation and these new habitats have remained relatively stable over the recent decades. Our results suggest an alternative future pathway where sub-arctic peatlands may at least partly sustain dry vegetation and enhance the carbon sink capacity of northern peatlands.

The expression of Oct3/4A mRNA and not its isoforms is upregulated by the HPV16 E7 oncoprotein.

PURPOSE: Oct3/4 a transcription factor is involved in maintaining the characteristics of cancer stem cells. Oct3/4 can be expressed differentially with respect to the progression of cervical cancer (CC). In addition, Oct3/4 can give rise to three isoforms by alternative splicing of the mRNA Oct3/4A, Oct3/4B and Oct3/4B1. The aim of this study was to evaluate the mRNA expression from Oct3/4A, Oct3/4B and Oct3/4B1 in low-grade squamous intraepithelial lesion (LSIL), high-grade squamous intraepithelial lesion (HSIL), CC samples, and measure the effect of the HPV16 E7 oncoprotein on the mRNA expression from Oct3/4 isoforms in the C-33A cell line. METHODS: The expression levels of Oct3/4A, Oct3/4B and Oct3/4B1 mRNA were analyzed by reverse transcription quantitative polymerase chain reaction (RT-qPCR) in patients with LSILs, HSILs and CC. Additionally, C-33A cells that expressed the HPV16 E7 oncoprotein were established to evaluate the effect of E7 on the expression of Oct3/4 mRNA isoforms. RESULTS: Oct3/4A (p = 0.02), Oct3/4B (p = 0. 001) and Oct3/4B1 (p < 0. 0001) expression is significantly higher in patients with LSIL, HSIL and CC than in woman with non-IL. In the C-33A cell line, the expression of Oct3/4A mRNA in the presence of the E7 oncoprotein increased compared to that in nontransfected C-33A cells. CONCLUSION: Oct3/4B and Oct3/4B1 mRNA were expressed at similar levels among the different groups. These data indicate that only the mRNA of Oct3/4A is upregulated by the HPV16 E7 oncoprotein.

Evaluation of the humoral and mucosal immune response of a multiepitope vaccine against COVID-19 in pigs.

Introduction: This study evaluated the immune response to a multiepitope recombinant chimeric protein (CHIVAX) containing B- and T-cell epitopes of the SARS-CoV-2 spike's receptor binding domain (RBD) in a translational porcine model for pre-clinical studies. Methods: We generated a multiepitope recombinant protein engineered to include six coding conserved epitopes from the RBD domain of the SARS-CoV-2 S protein. Pigs were divided into groups and immunized with different doses of the protein, with serum samples collected over time to determine antibody responses by indirect ELISA and antibody titration. Peptide recognition was also analyzed by Western blotting. A surrogate neutralization assay with recombinant ACE2 and RBDs was performed. Intranasal doses of the immunogen were also prepared and tested on Vietnamese minipigs. Results: When the immunogen was administered subcutaneously, it induced specific IgG antibodies in pigs, and higher doses correlated with higher antibody levels. Antibodies from immunized pigs recognized individual peptides in the multiepitope vaccine and inhibited RBD-ACE2 binding for five variants of concern (VOC). Comparative antigen delivery methods showed that both, subcutaneous and combined subcutaneous/intranasal approaches, induced specific IgG and IgA antibodies, with the subcutaneous approach having superior neutralizing activity. CHIVAX elicited systemic immunity, evidenced by specific IgG antibodies in the serum, and local mucosal immunity, indicated by IgA antibodies in saliva, nasal, and bronchoalveolar lavage secretions. Importantly, these antibodies demonstrated neutralizing activity against SARS-CoV-2 in vitro. Discussion: The elicited antibodies recognized individual epitopes on the chimeric protein and demonstrated the capacity to block RBD-ACE2 binding of the ancestral SARS-CoV-2 strain and four VOCs. The findings provide proof of concept for using multiepitope recombinant antigens and a combined immunization protocol to induce a neutralizing immune response against SARS-CoV-2 in the pig translational model for preclinical studies.

Ivermectin compared with placebo in the clinical course in Mexican patients with asymptomatic and mild COVID-19: a randomized clinical trial.

BACKGROUND: Despite the development and application of vaccines against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) around the world, the scientific community is still trying to find some therapies to avoid or ameliorate the fatal evolution of the Coronavirus disease 2019 (COVID-19). Since the publication of the potential use of ivermectin as a treatment against the disease, a pleiad of information about it has been published. However, the evidence is not strong or weak enough to conclude its usefulness in the clinical evolution of patients infected with SARS-CoV-2. We evaluate the efficacy and safety of ivermectin in the treatment of Mexican patients with asymptomatic and mild COVID-19 in a three-day administration in comparison to placebo. METHODS: A randomized, double-blind, placebo-controlled trial was carried out in 66 adults with asymptomatic and mild COVID-19. Patients were randomly assigned 1:1 ratio to ivermectin plus acetaminophen or placebo plus acetaminophen. The primary endpoint was the proportion of subjects without a disease progression to severity according to COVID-19 guidelines by the National Institutes of Health (NIH) since randomization to 14 days. RESULTS: None of the participants presented progression to a severe state in either group. Viral load was measured on Days 1, 5, and 14. No significant differences were observed in baseline or 14-day between groups (p = 0.720 and 0.362, respectively). However, on Day 5, a significant difference in viral load was observed between groups (p = 0.039). The frequency of symptoms was similar between groups, and no significant differences were observed. The most frequent symptom was cough. One severe adverse event associated with SARS-CoV-2 infection was observed in the ivermectin group. CONCLUSIONS: At standard doses, ivermectin is not effective to prevent progression to a severe state or reducing symptoms in adults with asymptomatic and mild COVID-19. Trial registration The study was registered with ClinicalTrial.gov (NCT04407507) on May 29, 2020.

Fulminant Herpes Pneumonia Postaortic Surgery with Known Ankylosing Spondylitis.

Herpes simplex virus (HSV) pneumonitis is rare after cardiac surgery. A 36-year-old gentleman with ankylosing spondylitis underwent emergency surgery for a complex aortic aneurysmal disease. Preoperative treatment of aortitis with antitumor necrosis factor and steroid medication and surgical stress including cardiopulmonary bypass potentially created an immunosuppressive state and reactivation of undiagnosed HSV. Rapid HSV pneumonia ensued, culminating in fulminant organ failure and mortality. HSV pneumonia should be considered postoperatively in patients with severe respiratory distress, especially if immunocompromised.

Genetic and compositional analysis of biofilm formed by Staphylococcus aureus isolated from food contact surfaces.

Introduction: Staphylococcus aureus is an important pathogen that can form biofilms on food contact surfaces (FCS) in the dairy industry, posing a serious food safety, and quality concern. Biofilm is a complex system, influenced by nutritional-related factors that regulate the synthesis of the components of the biofilm matrix. This study determines the prevalence of biofilm-associated genes and evaluates the development under different growth conditions and compositions of biofilms produced by S. aureus. Methods: Biofilms were developed in TSB, TSBG, TSBNaCl, and TSBGNaCl on stainless-steel (SS), with enumeration at 24 and 192 h visualized by epifluorescence and scanning electron microscopy (SEM). The composition of biofilms was determined using enzymatic and chemical treatments and confocal laser scanning microscopy (CLSM). Results and discussion: A total of 84 S. aureus (SA1-SA84) strains were collected from 293 dairy industry FCS (FCS-stainless steel [n = 183] and FCS-polypropylene [n = 110]) for this study. The isolates harbored the genes sigB (66%), sar (53%), agrD (52%), clfB/clfA (38%), fnbA/fnbB (20%), and bap (9.5%). 99. In particular, the biofilm formed by bap-positive S. aureus onto SS showed a high cell density in all culture media at 192 h in comparison with the biofilms formed at 24 h (p < 0.05). Epifluorescence microscopy and SEM revealed the metabolically active cells and the different stages of biofilm formation. CLSM analysis detected extracellular polymeric of S. aureus biofilms on SS, such as eDNA, proteins, and polysaccharides. Finally, the level of detachment on being treated with DNase I (44.7%) and NaIO 4(42.4%) was greater in the biofilms developed in TSB compared to culture medium supplemented with NaCl at 24 h; however, there was no significant difference when the culture medium was supplemented with glucose. In addition, after treatment with proteinase K, there was a lower level of biomass detachment (17.7%) of the biofilm developed in TSBNaCl (p < 0.05 at 24 h) compared to that in TSB, TSBG, and TSBGNaCl (33.6, 36.9, and 37.8%, respectively). These results represent a deep insight into the composition of S. aureus biofilms present in the dairy industry, which promotes the development of more efficient composition-specific disinfection strategies.