7 research outputs found
Sustainable recovery and advanced use of nanostructured cellulose from agri-food residues
No full text2021 - 2022In recent years, there has been a growing interest in the development of sustainable alternative materials
due to the environmental impacts related to the high disposal of fossil oil-based products. In this regard,
cellulose is a key constituent and an attractive feedstock as one of the most abundant, cost effective, renewable,
and biodegradable biopolymers in nature. Cellulose is characterized by noteworthy structure and properties
due to its unique molecular structure, consisting of a highly ordered polymer of cellobiose unbranched chains
of β-1, 4-linked glucose units, which act as a framework for the three-dimensional polysaccharide structure.
The promising chemical (such as hydrophilicity, chirality, degradability, and broad chemical variability) and
mechanical (non-toxic, biocompatible, renewable, and biodegradable) properties of cellulose have aroused
increasing interest as building blocks for the development of new biomaterials, especially through advanced
nanotechnology tools, which enables further promotion of its techno-functional attributes. Nevertheless
nowadays, cellulose is isolated from wood sources, and as structural plant component is much more difficult
to deconstruct. Indeed, its innate close polymeric alignment and its intimate relationship with other
lignocellulosic components such as hemicellulose and lignin limit the accessibility to cellulose. A
delignification process with effective harsh acid or alkaline chemical hydrolysis treatment to split cellulose
and hemicelluloses from lignin is a crucial step and undoubtedly the most challenging. However, these current
methods are expensive and energy consuming and utilize chemicals which entail special disposal, handling or
production procedures. Taking into account environmental sustainability, it is counterproductive to combine
energy-severe, wasteful processes on wood sources.
In the context explained above, the works carried out during this Ph.D. thesis have demonstrated that the
process required to enhance cellulose accessibility and recovery is strongly influenced by the nature of the
native biomass. Consequently, agri-food residues/by-products (AFRs) represent a new and promising
feedstock for the development of new sustainable processes to isolate cellulose established on nonconventional
technologies with low environmental and economic impacts and high efficiency, emphasizing the stringent
need to also diversify and valorize the biobased waste with circular economy strategies. In this context, high pressure homogenization (HPH), nonthermal and purely physical treatment, is here exploited for the first time
to increase the efficiency of mild chemical hydrolysis processing for isolation of cellulose from agri-food
residues (increasing the cumulative yield extraction of about 20%), while leading to a drastic reduction in the
use of chemicals, shortening the processing times by process intensification, enhancing purity, inducing a
defibrillated cellulose structure, are enabling the concurrent recovery of high-value-added bioactive
compounds with high antioxidant capacity in the side streams. Moreover, the fluid-mechanical stresses (high
shear, elongation, turbulence and hydrodynamic cavitation) occurring during the HPH treatment, in
combination with mild hydrolysis, improved the cellulose defibrillation and contributed to trimming down the
length of the fibers. The comprehensive utilization of AFRs feedstocks has attracted considerable interest also
for the development of new sustainable processes established on bottom-up green constructing strategy. The
work was undertaken for the recovery of the biofilm by-product derived from Kombucha tea fermentation
process using micronized AFRs as carbon source in alternative to the conventional synthetic media to decrease
the culture media costs and enhance the yield production, to obtain nanostructured cellulose with remarkable
biological and physico-mechanical properties. These isolation routes allowed the achievement of cellulose
pulp with tailored morphological properties from underused AFRs feedstocks or by-products of fermentation
processes (evaluated through light scattering for particle size distribution, optical and scanning electron
microscopy, and FT-IR analysis), decreasing the severity of conventional chemical processes and increasing
the exploitation of low-cost industrial by-products. From the overall results collected in this section, the
efficient cellulose extraction has been accomplished along with the valorization of the value-added compounds
still contained in the AFRs biomass. [edited by Author]Negli ultimi anni c'è stato un crescente interesse nello sviluppo di materiali alternativi sostenibili a causa
degli impatti ambientali legati all'alto smaltimento di prodotti derivati dal petrolio fossile. In questo contesto,
la cellulosa è un componente chiave e una materia prima interessante in quanto uno dei biopolimeri più
abbondanti, economici, rinnovabili e biodegradabili presenti in natura. La cellulosa è caratterizzata da catene
di cellobiosio non ramificate collegate in modo β-1,4 al glucosio, che agiscono come una struttura
tridimensionale per il polisaccaride. Le promettenti proprietà chimiche (come l'idrofilia, la chiralità, la
degradabilità e la vasta variabilità chimica) e meccaniche (non tossiche, biocompatibili, rinnovabili e
biodegradabili) della cellulosa hanno suscitato un interesse crescente per lo sviluppo di nuovi biomateriali,
specialmente attraverso strumenti avanzati di nanotecnologia, che migliorano le sue proprietà tecno-funzionali.
Tuttavia, attualmente la cellulosa viene isolata da fonti legnose ed è molto più difficile destrutturarla come
componente strutturale delle piante. Infatti, la sua stretta disposizione polimerica e i forti legami con altri
componenti lignocellulosici, come l'emicellulosa e la lignina, limitano l’isolamento della cellulosa. Un
processo di delignificazione con un efficace trattamento di idrolisi chimica acida o alcalina per separare la
cellulosa e l'emicellulosa dalla lignina è un passaggio cruciale. Tuttavia, i metodi attuali sono costosi,
consumano molta energia e utilizzano prodotti chimici che richiedono procedure di trattamento a valle e/o di
smaltimento. Tenendo conto della sostenibilità ambientale, è controproducente combinare processi energetici
sulle fonti legnose.
In questo contesto, il lavoro di questa tesi di dottorato dimostrata che il processo necessario per aumentare
l'accessibilità e il recupero della cellulosa è fortemente influenzato dalla natura della biomassa nativa. Di
conseguenza, i residui/sottoprodotti agroalimentari rappresentano una nuova e promettente materia prima per
lo sviluppo di nuovi processi sostenibili per isolare la cellulosa, basati su tecnologie non convenzionali con
bassi impatti ambientali ed economici ed elevata efficienza, sottolineando l'urgente necessità di diversificare e
valorizzare i rifiuti con strategie di economia circolare. In questo contesto, la omogeneizzazione ad alta
pressione (high-pressure homogenization, HPH), un trattamento non termico e puramente fisico, viene usato
per la prima volta per aumentare l'efficienza del trattamento di idrolisi chimica delicata per l'isolamento della
cellulosa dai residui agroalimentari (aumentando la resa di estrazione del 20% circa), riducendo drasticamente
l'uso di prodotti chimici, riducendo i tempi di lavorazione grazie all'intensificazione del processo, migliorando
la purezza e inducendo una defibrillazione della struttura di cellulosa, consentendo contemporaneamente il
recupero di composti bioattivi ad alto valore aggiunto con elevata capacità antiossidante dalle correnti di scarto.
Inoltre, gli stress fluido-meccanici (alta forza di taglio, turbolenza e cavitazione idrodinamica) che si verificano
durante il trattamento HPH, in combinazione con l'idrolisi, migliorano la defibrillazione della cellulosa e
contribuiscono a ridurre la lunghezza delle fibre. L'utilizzo completo di materie prime da residui/sottoprodotti
agroalimentari ha suscitato un notevole interesse anche per lo sviluppo di nuovi processi sostenibili basati sulla
strategia green bottom-up. In questo senso, il lavoro è stato svolto per il recupero di biofilm derivati dal
processo di fermentazione del tè Kombucha utilizzando AFRs micronizzati come fonte di carbonio, in
alternativa ai mezzi sintetici convenzionali, per ridurre i costi dei mezzi di coltura e aumentare la produzione,
al fine di ottenere cellulosa nanostrutturata con notevoli proprietà biologiche e fisico-meccaniche. Tutti queti
approcci hanno permesso di isolare la cellulosa con specifiche proprietà morfologiche da residui/sottoprodotti
agroalimentari o sottoprodotti di processi di fermentazione (valutate mediante dimensioni delle particelle,
microscopia ottica ed elettronica a scansione e analisi FT-IR), riducendo l'intensità dei processi chimici
convenzionali e aumentando lo sfruttamento di sottoprodotti industriali a basso costo. Dai risultati complessivi,
un’efficiente estrazione di cellulosa è stata realizzata insieme alla valorizzazione dei composti ad alto valore
aggiunto ancora presenti nella biomassa degli scarti agroalimentari. [a cura dell'Autore]XXXV cicl
Epidemiology of intra-abdominal infection and sepsis in critically ill patients: “AbSeS”, a multinational observational cohort study and ESICM Trials Group Project
No full textPurpose: To describe the epidemiology of intra-abdominal infection in an international cohort of ICU patients according to a new system that classifies cases according to setting of infection acquisition (community-acquired, early onset hospital-acquired, and late-onset hospital-acquired), anatomical disruption (absent or present with localized or diffuse peritonitis), and severity of disease expression (infection, sepsis, and septic shock). Methods: We performed a multicenter (n = 309), observational, epidemiological study including adult ICU patients diagnosed with intra-abdominal infection. Risk factors for mortality were assessed by logistic regression analysis. Results: The cohort included 2621 patients. Setting of infection acquisition was community-acquired in 31.6%, early onset hospital-acquired in 25%, and late-onset hospital-acquired in 43.4% of patients. Overall prevalence of antimicrobial resistance was 26.3% and difficult-to-treat resistant Gram-negative bacteria 4.3%, with great variation according to geographic region. No difference in prevalence of antimicrobial resistance was observed according to setting of infection acquisition. Overall mortality was 29.1%. Independent risk factors for mortality included late-onset hospital-acquired infection, diffuse peritonitis, sepsis, septic shock, older age, malnutrition, liver failure, congestive heart failure, antimicrobial resistance (either methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum beta-lactamase-producing Gram-negative bacteria, or carbapenem-resistant Gram-negative bacteria) and source control failure evidenced by either the need for surgical revision or persistent inflammation. Conclusion: This multinational, heterogeneous cohort of ICU patients with intra-abdominal infection revealed that setting of infection acquisition, anatomical disruption, and severity of disease expression are disease-specific phenotypic characteristics associated with outcome, irrespective of the type of infection. Antimicrobial resistance is equally common in community-acquired as in hospital-acquired infection. © 2019, The Author(s)
Poor timing and failure of source control are risk factors for mortality in critically ill patients with secondary peritonitis
No full textPurpose: To describe data on epidemiology, microbiology, clinical characteristics and outcome of adult patients admitted in the intensive care unit (ICU) with secondary peritonitis, with special emphasis on antimicrobial therapy and source control.
Methods: Post hoc analysis of a multicenter observational study (Abdominal Sepsis Study, AbSeS) including 2621 adult ICU patients with intra-abdominal infection in 306 ICUs from 42 countries. Time-till-source control intervention was calculated as from time of diagnosis and classified into 'emergency' (< 2 h), 'urgent' (2-6 h), and 'delayed' (> 6 h). Relationships were assessed by logistic regression analysis and reported as odds ratios (OR) and 95% confidence interval (CI).
Results: The cohort included 1077 cases of microbiologically confirmed secondary peritonitis. Mortality was 29.7%. The rate of appropriate empiric therapy showed no difference between survivors and non-survivors (66.4% vs. 61.3%, p = 0.1). A stepwise increase in mortality was observed with increasing Sequential Organ Failure Assessment (SOFA) scores (19.6% for a value ≤ 4-55.4% for a value > 12, p < 0.001). The highest odds of death were associated with septic shock (OR 3.08 [1.42-7.00]), late-onset hospital-acquired peritonitis (OR 1.71 [1.16-2.52]) and failed source control evidenced by persistent inflammation at day 7 (OR 5.71 [3.99-8.18]). Compared with 'emergency' source control intervention (< 2 h of diagnosis), 'urgent' source control was the only modifiable covariate associated with lower odds of mortality (OR 0.50 [0.34-0.73]).
Conclusion: 'Urgent' and successful source control was associated with improved odds of survival. Appropriateness of empirical antimicrobial treatment did not significantly affect survival suggesting that source control is more determinative for outcome
Antimicrobial lessons from a large observational cohort on intra-abdominal infections in intensive care units
No full textSevere intra-abdominal infection commonly requires intensive care. Mortality is high and is mainly determined by disease-specific characteristics, i.e. setting of infection onset, anatomical barrier disruption, and severity of disease expression. Recent observations revealed that antimicrobial resistance appears equally common in community-acquired and late-onset hospital-acquired infection. This challenges basic principles in anti-infective therapy guidelines, including the paradigm that pathogens involved in community-acquired infection are covered by standard empiric antimicrobial regimens, and second, the concept of nosocomial acquisition as the main driver for resistance involvement. In this study, we report on resistance profiles of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterococcus faecalis and Enterococcus faecium in distinct European geographic regions based on an observational cohort study on intra-abdominal infections in intensive care unit (ICU) patients. Resistance against aminopenicillins, fluoroquinolones, and third-generation cephalosporins in E. coli, K. pneumoniae and P. aeruginosa is problematic, as is carbapenem-resistance in the latter pathogen. For E. coli and K. pneumoniae, resistance is mainly an issue in Central Europe, Eastern and South-East Europe, and Southern Europe, while resistance in P. aeruginosa is additionally problematic in Western Europe. Vancomycin-resistance in E. faecalis is of lesser concern but requires vigilance in E. faecium in Central and Eastern and South-East Europe. In the subcohort of patients with secondary peritonitis presenting with either sepsis or septic shock, the appropriateness of empiric antimicrobial therapy was not associated with mortality. In contrast, failure of source control was strongly associated with mortality. The relevance of these new insights for future recommendations regarding empiric antimicrobial therapy in intra-abdominal infections is discussed
Epidemiology of intra-abdominal infection and sepsis in critically ill patients: "AbSeS", a multinational observational cohort study and ESICM Trials Group Project
No full textPurposeTo describe the epidemiology of intra-abdominal infection in an international cohort of ICU patients according to a new system that classifies cases according to setting of infection acquisition (community-acquired, early onset hospital-acquired, and late-onset hospital-acquired), anatomical disruption (absent or present with localized or diffuse peritonitis), and severity of disease expression (infection, sepsis, and septic shock).MethodsWe performed a multicenter (n=309), observational, epidemiological study including adult ICU patients diagnosed with intra-abdominal infection. Risk factors for mortality were assessed by logistic regression analysis.ResultsThe cohort included 2621 patients. Setting of infection acquisition was community-acquired in 31.6%, early onset hospital-acquired in 25%, and late-onset hospital-acquired in 43.4% of patients. Overall prevalence of antimicrobial resistance was 26.3% and difficult-to-treat resistant Gram-negative bacteria 4.3%, with great variation according to geographic region. No difference in prevalence of antimicrobial resistance was observed according to setting of infection acquisition. Overall mortality was 29.1%. Independent risk factors for mortality included late-onset hospital-acquired infection, diffuse peritonitis, sepsis, septic shock, older age, malnutrition, liver failure, congestive heart failure, antimicrobial resistance (either methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum beta-lactamase-producing Gram-negative bacteria, or carbapenem-resistant Gram-negative bacteria) and source control failure evidenced by either the need for surgical revision or persistent inflammation.ConclusionThis multinational, heterogeneous cohort of ICU patients with intra-abdominal infection revealed that setting of infection acquisition, anatomical disruption, and severity of disease expression are disease-specific phenotypic characteristics associated with outcome, irrespective of the type of infection. Antimicrobial resistance is equally common in community-acquired as in hospital-acquired infection
Poor timing and failure of source control are risk factors for mortality in critically ill patients with secondary peritonitis
No full textPurpose To describe data on epidemiology, microbiology, clinical characteristics and outcome of adult patients admitted in the intensive care unit (ICU) with secondary peritonitis, with special emphasis on antimicrobial therapy and source control. Methods Post hoc analysis of a multicenter observational study (Abdominal Sepsis Study, AbSeS) including 2621 adult ICU patients with intra-abdominal infection in 306 ICUs from 42 countries. Time-till-source control intervention was calculated as from time of diagnosis and classified into 'emergency' (< 2 h), 'urgent' (2-6 h), and 'delayed' (> 6 h). Relationships were assessed by logistic regression analysis and reported as odds ratios (OR) and 95% confidence interval (CI). Results The cohort included 1077 cases of microbiologically confirmed secondary peritonitis. Mortality was 29.7%. The rate of appropriate empiric therapy showed no difference between survivors and non-survivors (66.4% vs. 61.3%, p = 0.1). A stepwise increase in mortality was observed with increasing Sequential Organ Failure Assessment (SOFA) scores (19.6% for a value <= 4-55.4% for a value > 12, p < 0.001). The highest odds of death were associated with septic shock (OR 3.08 [1.42-7.00]), late-onset hospital-acquired peritonitis (OR 1.71 [1.16-2.52]) and failed source control evidenced by persistent inflammation at day 7 (OR 5.71 [3.99-8.18]). Compared with 'emergency' source control intervention (< 2 h of diagnosis), 'urgent' source control was the only modifiable covariate associated with lower odds of mortality (OR 0.50 [0.34-0.73]). Conclusion 'Urgent' and successful source control was associated with improved odds of survival. Appropriateness of empirical antimicrobial treatment did not significantly affect survival suggesting that source control is more determinative for outcome
Epidemiology of intra-abdominal infection and sepsis in critically ill patients: "AbSeS", a multinational observational cohort study and ESICM Trials Group Project
No full textAbstract: PurposeTo describe the epidemiology of intra-abdominal infection in an international cohort of ICU patients according to a new system that classifies cases according to setting of infection acquisition (community-acquired, early onset hospital-acquired, and late-onset hospital-acquired), anatomical disruption (absent or present with localized or diffuse peritonitis), and severity of disease expression (infection, sepsis, and septic shock).MethodsWe performed a multicenter (n=309), observational, epidemiological study including adult ICU patients diagnosed with intra-abdominal infection. Risk factors for mortality were assessed by logistic regression analysis.ResultsThe cohort included 2621 patients. Setting of infection acquisition was community-acquired in 31.6%, early onset hospital-acquired in 25%, and late-onset hospital-acquired in 43.4% of patients. Overall prevalence of antimicrobial resistance was 26.3% and difficult-to-treat resistant Gram-negative bacteria 4.3%, with great variation according to geographic region. No difference in prevalence of antimicrobial resistance was observed according to setting of infection acquisition. Overall mortality was 29.1%. Independent risk factors for mortality included late-onset hospital-acquired infection, diffuse peritonitis, sepsis, septic shock, older age, malnutrition, liver failure, congestive heart failure, antimicrobial resistance (either methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum beta-lactamase-producing Gram-negative bacteria, or carbapenem-resistant Gram-negative bacteria) and source control failure evidenced by either the need for surgical revision or persistent inflammation.ConclusionThis multinational, heterogeneous cohort of ICU patients with intra-abdominal infection revealed that setting of infection acquisition, anatomical disruption, and severity of disease expression are disease-specific phenotypic characteristics associated with outcome, irrespective of the type of infection. Antimicrobial resistance is equally common in community-acquired as in hospital-acquired infection
