30 research outputs found
Constraints on magma source, pre-eruptive dynamics and timescales of the 2009 major explosions at Stromboli volcano (Italy)
No full textStromboli is one of the best studied and monitored open-vent volcanoes worldwide, but still our understanding of the magma source, triggering mechanisms and ascent timescales of larger explosive events than the normal Strombolian activity remains incomplete. Within this variability, major explosions are relatively frequent (1-4 events/year) explosive eruptions of intermediate intensity between the recurrent (10 events/hour) and low-intensity regular Strombolian eruption and the more violent and rarer eruptive paroxysms (with the most recent occurred in 2003, 2007 and 2019). While regular explosions are fed by a crystal-rich (HP, high porphyricity) magma residing in a degassed shallow reservoir (< 3 km), and paroxysms by volatile-rich (LP, low porphyricity) magma rapidly ascending from the deep portions of the plumbing system (6-9 km b.s.l. down to the crust-mantle interface), much less is known about the magma source of major explosions.
Here we present a comprehensive dataset on dissolved volatile contents (H2O, CO2, S and Cl) in olivine-hosted melt inclusions (MI), embayments and glassy matrix, coupled to major element compositions and Fe-Mg diffusion profiles in olivine phenocrysts from three major explosions which occurred on 3 May, 8 November and 24 November 2009. Each of these events consisted of a brief explosive sequence that erupted coarser and more widely dispersed tephra than ordinary eruptive activity, with the 24 November 2009 event being the most energetic one.
Olivine-hosted melt inclusions from the 24 November 2009 event have dissolved H2O ranging from ca. 0.22 to 2.37 wt% and CO2 generally below the detection limit, with a maximum recorded of 576 ppm. Major elements composition of melt inclusions varies from the compositional field of HP products toward the LP compositional field. Two distinct compositional clusters (one overlapping with the HP compositional field and one overlapping the LP one) are observed in the glass wetting the phenocrysts, with no intermediate compositions. Excluding the rare occurrence of homogeneous evolved olivines (Fo70), the majority are variably reversely zoned, with Mg-richer (Fo77-83) reaction rims (50-100 μm thick). Melt inclusions from the 8 November 2009 event have H2O ranging from ca. 0.15 to 0.55 wt% and CO2 always below the detection limit. Melt inclusions from the 3 May 2009 event have H2O ranging from ca. 0.15 to 0.75 wt% and CO2 generally below the detection limit and max. 291 ppm, major elements composition overlaps the HP compositional field. The host olivines are compositionally homogeneous and evolved (Fo70-72).
Volatile contents of MI (EMPA and FTIR) suggest that these explosions are fed by more degassed, shallow stored magma if compared to paroxysms. Preliminary data suggest a positive correlation between eruption magnitude and volatile content. Volatile elements are higher in the most energetic major explosion of 24 November 2009, which erupted larger volumes of coarser pyroclasts of both HP and LP magma that eventually reached the coast of the island. In contrast, the 8 November and 3 May events ejected a smaller volume of pyroclasts (mostly confined to the summit area of the volcano) with a minor LP component, suggesting a shallower source origin
Application of paleomagnetic methods on two variably welded peralkaline fallout deposits from Pantelleria Island (Sicily Strait): inferences on emplacement temperature and welding
No full textOne of the major volcanological issues is to outline the eruptive and depositional mechanisms of explosive eruptions and to constrain the emplacement temperature (Temp) of the associated pyroclastic deposits for the inferences on the thermal evolution, welding and rheomorphism, before cooling to the glass transition temperature (Tg).
Emplacement temperature of pyroclastic deposits, in particular ignimbrites, can be constrained using paleomagnetic methods on lithic clasts entrained during eruptive climax. At Pantelleria island, a paleomagnetic study was carried out on the Green Tuff welded and rheomorphic ignimbrite [Scarani et al., 2023], but there is limited understanding of less explosive inter-ignimbritic eruptions.
Here we provide paleomagnetic data of two variably welded fallout deposits belonging to the old local centres of Cala dell’Altura (pantelleritic) and Cala delle Giache (comenditic), in the attempt to ascertain any possible relationship of welding degree of peralkaline airfalls with the emplacement temperature recorded by lithic clasts.
Thermal demagnetization of lithic clasts does not show evident relationships with welding in the Cala dell’Altura fallout, indicating that unwelded and welded layers were emplaced at the same temperature range between the TCurie of magnetite (580 °C) and T pre-eruptive (700°C for pantelleritic magma, 800 °C for comenditic), thus suggesting poorly efficient cooling (low column height or high deposition rate). On the contrary the Cala Giache fallout, characterized by some initial phreatomagmatic episodes, shows an evident bimodality, with lithics in the welded layers emplaced at high temperature (580-800°C) and those in the unwelded layers at lower temperature, pointing out to a more efficient cooling, possibly due to early magma-water interaction and/or lower deposition rate.
Post-depositional magnetic disturbance occurred in proximity of some large (30 cm in length) lithics, deforming very local (cm-scale) geomagnetic field and affecting the magnetic orientation of smaller lithics nearby. Secondarily, we detected post-depositional tilting of few lithics due to sliding along the unconsolidated matrix of the unwelded fallouts
The role of a monthly active surveillance programme for multidrug-resistant Gram-negative bacteria in a neonatal intensive care unit: impact evaluation of preventive measures
No full textBackground: Antimicrobial resistance is a public health threat. Neonatal Intensive Care Unit (NICU) patients are particularly at risk, due to the large use of invasive devices and antimicrobial treatment.
Since 2014 an active surveillance program of multidrug-resistant organisms is in place in the five NICUs of Palermo, Italy. High prevalence of multidrug-resistant Gram-negative bacteria (MDR-GNB) carriage observed in one NICU suggested the need of a long-lasting approach to achieve effective control of MDR-GNB circulation.
Materials/methods: Rectal swabs were obtained every month from each hospitalized new-born. Samples were enriched in liquid cultures, plated in McConkey Agar with three antimicrobial discs (amoxicillin-clavulanate, meropenem, ceftazidime). Resistant colonies were isolated, identified and submitted for antimicrobial susceptibility testing and ESBL detection. Molecular characterization of MDR-GNB was performed using pulsed-field gel electrophoresis (PFGE).
From November 2017 multiple intervention measures were done:
- Strengthening of sample collection for two months;
- Stakeholders meetings;
- Standardized protocols for antimicrobial therapy and common procedures.
Prevalence of MDR-GNB carriage between the pre-intervention (November 2016-October 2017) and the post-intervention period (November 2017-October 2018) was compared by chi-square test. Clinical features were analysed in a subgroup of patients to identify possible risk factors. All associated variables with p-values <0.25 were included in a multivariate logistic regression model. P<0.05 was considered significant.
Results: 39 patients were included in the 2 months of strengthened microbiological surveillance. MDR-GNB and ESBL-Klebsiella pneumoniae (KP) were detected in rectal swabs (34.8%; 23.2%), nasal swabs (24.6%; 14.5%), oral swabs (14.5%; 5.4%), milk samples (32.1%; 17.9%) soother swabs (30.8%; 17.9%). ESBL-KP was also detected from a sub-intensive room surface. Thirteen ESBL-KP strains isolated from clinical and environmental samples showed identical or closely related PFGE patterns suggesting a common origin for all tested strains. Prevalence of MDR-GNB and ESBL-KP carriage after intervention significantly decreased compared to the year before (61.1% vs 20.6%; p<0.001 and 94.5% vs 53.8%; p<0.001). Admission in post-intervention period
significantly reduced the risk of MDR-GNB carriage (OR=0.15, p=0.01).
Conclusions: MDR-GNB broadly circulate in NICU setting, can colonize different body sites and spread by various vehicles.
Cooperation between epidemiologist and clinicians can effectively reduce diffusion of antimicrobial-resistant bacteria
Surveillance of methicillin-resistant Staphylococcus aureus, multidrug-resistant Gram-negatives and fungi colonization in the Neonatal Intensive Care Units in the city of Palermo.
No full textIntroduction
Multidrug-resistant organisms are a serious public health problem, particularly in critical hospital wards such as the Neonatal Intensive Care Units (NICUs). Hospitalized neonates are at high risk for healthcare-associated infections leading to higher morbidity and mortality rates, because of their poor immune defences, frequent exposure to antibiotics, invasive procedures and contacts with healthcare-workers.
Our study aimed to evaluate the prevalence of colonization by methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Gram-negatives (MDRGNs) and fungi in the five NICUs of the city of Palermo.
Methods
From February 2014 to January 2015, an active surveillance culture (ACS) program was set up in the five NICUs of Palermo (ARNAS Civico-NICU1, Ingrassia Hospital-NICU2, Villa Sofia-Cervello Hospital-NICU3, Buccheri La Ferla Hospital-NICU4 and AOUP "Paolo Giaccone"-NICU5). From each patient nasal and rectal swabs were monthly collected to look for MRSA, MDRGNs and fungi.
Swabs were pre-incubated at 37°C overnight in BHI enrichment broth, and cultured on selective media. Suspected S. aureus colonies were confirmed by cefoxitin susceptibility testing.
MDRGNs were selected by antibiotic disk screening and tested to detect extended-spectrum beta-lactamase” (ESBL) and carbapenemase-producing isolates.
For fungal detection swabs were directly inoculated on chloramphenicol-Sabouraud dextrose agar plates and incubated at 30°C for 72 hrs. Yeast-like colonies were identified by subculturing on CHROMagar Candida and eventually confirmed by the API20CAUX test.
Prevalence rates of colonization of the different NICUs were compared by the chi-square test.
Results
The average daily number of hospitalized patients was 16 in NICU1, 9 in NICU2, 21 in NICU3, 15 in NICU4, 11 in NICU5.
Prevalence of MRSA colonization ranged between 3.6% in NICU3 and 28.8% in NICU4, showing statistically significant differences between the NICUs. Prevalence of colonization by MDRGNs ranged between 53.9% for NICU1 and 14% for NICU4 with statistically significant differences between the NICUs. The most frequently isolated MDRGN organisms were Klebsiella pneumoniae, Escherichia coli and Enterobacter spp., with a prevalence between 1.9% and 57.2% for ESBL-producing and between 0% and 3.5% for carbapenemase-producing isolates. Fungal colonization was never detected in NICU2, whilst the highest prevalence values were 7.2% for C. albicans in NICU4 and 5.9% for non-albicans Candida spp. in NICU5. Statistically significant differences were found.
Discussion
Spread of multidrug-resistant organisms proved to affect all the NICUs under investigation, with a higher prevalence of MRSA in NICUs 4 and 2 and a higher prevalence of MDRGNs in NICUs 1 and 5. Fungal colonization prevalence was different between the NICUs with NICU4 being more affected by C.albicans and NICU5 by non-albicans Candida spp.
These differences could be attributable to different structural and organizational characteristics and the recurrent epidemic spread of some organisms by cross-transmission.
The widespread dissemination of MRSA and ESBL producing isolates and the emergence of carbapenem-resistant Enterobacteriaceae require a continuous effort in implementing preventive measures, control interventions and staff training
SORVEGLIANZA DELLE COLONIZZAZIONI DA CANDIDA SPP. IN TERAPIA INTENSIVA NEONATALE
No full textCandida spp., colonizzazione, UTI
Candida SPP. Colonization in NICU: A 2-Year Surveillance Study
Get PDFIntroduction: Fungal infections are an important cause of increased morbidity and mortality in infants admitted to neonatal intensive care units (NICUs). In VLBW infants, Candida (C.) albicans is the third most common cause of neonatal late onset sepsis (LOS). The overall incidence of candidemia in NICU is increasing because of the longer survival and the invasive procedures related with the intensive care of extremely preterm infants. Prevention of candidemia in neonates is supported by the identification and adequate management of specific risk factors, including low birth weight, use of invasive devices, prolonged hospitalization and use of broad-spectrum antimicrobial agents. Effective prophylactic strategies have recently become available, but the identification of the best possible strategies to manage high-risk infants is still a priority. Prior colonization is a key risk factor for candidemia. For this reason, surveillance studies to monitor incidence, species distribution, and antifungal susceptibility profiles are mandatory.
Materials and Methods: In 2013 and 2014, we performed a cohort, prospective surveillance study in our NICU, collecting weekly nasal and rectal swabs. For each patient, clinical and demographic data expected to affect Candida colonization were recorded. We evaluated Candida spp. colonization rate and assessed the related risk factors. Swabs were placed on Sabouraud agar and incubated at 30°C for 4 days. Candida growth on agar was confirmed by microscopic observation. Moreover, Candida spp. were identified through Candida chromogenic agar (ChromAgar Candida, Laboratorios Conda) and API® 20C AUX (Biomérieux). Statistical analysis was performed by EpiInfo (CDC software) using the chi square or the Fisher’s exact method, when indicated. We assumed as statistically significant a p-value < 0.05.
Results: In this 2-year study, we enrolled 520 patients and we analyzed 1,259 nasal and 1,255 rectal swabs. From 472 out of 520 patients we collected complete microbiological, clinical and demographic data. 48 out of 472 (10.17%) patients tested positive for Candida spp. at least once. In particular, 26 patients tested positive for C. albicans, 16 for C. parapsilosis, 6 for C. glabrata and 1 each for C. guilliermondii and an environmental mold. All the colonized patients had their rectal samples positive, and 7 their nasal samples as well. 15 patients out of 472 (3.18%) had more than one rectal or nasal swab positive during their NICU stay. Importantly, 9 patients out of 15 tested negative at the first sampling, suggesting that they have acquired Candida spp. colonization during their stay. Table 1 summarizes data about risk factors for Candida colonization in the patients under study. No systemic infection by Candida spp. was reported during the study.
Conclusion: Our experience suggest that an effective microbiological surveillance can allow for implementing proper, effective and timely control measures in a high-risk setting
The Increasing Challenge of Multidrug-Resistant Gram-Negative Bacilli: Results of a 5-Year Active Surveillance Program in a Neonatal Intensive Care Unit
Get PDFColonization and infection by multidrug-resistant gram-negative bacilli (MDR GNB) in neonatal intensive care units (NICUs) are increasingly reported.We conducted a 5-year prospective cohort surveillance study in a tertiary NICU of the hospital "Paolo Giaccone," Palermo, Italy. Our objectives were to describe incidence and trends of MDR GNB colonization and the characteristics of the most prevalent organisms and to identify the risk factors for colonization. Demographic, clinical, and microbiological data were prospectively collected. Active surveillance cultures (ASCs) were obtained weekly. Clusters of colonization by extended spectrum β-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae were analyzed by conventional and molecular epidemiological tools.During the study period, 1152 infants were enrolled in the study. Prevalences of colonization by MDR GNB, ESBL-producing GNB and multiple species/genera averaged, respectively, 28.8%, 11.7%, and 3.7%. Prevalence and incidence density of colonization by MDR GNB and ESBL-producing GNB showed an upward trend through the surveillance period. Rates of ESBL-producing E coli and K pneumoniae colonization showed wide fluctuations peaking over the last 2 years. The only independent variables associated with colonization by MDR GNB and ESBL-producing organisms and multiple colonization were, respectively, the days of NICU stay (odds ratio [OR] 1.041), the days of exposure to ampicillin-sulbactam (OR 1.040), and the days of formula feeding (OR 1.031). Most clusters of E coli and K pneumoniae colonization were associated with different lineages. Ten out of 12 clusters had an outborn infant as their index case.Our study confirms that MDR GNB are an increasing challenge to NICUs. The universal once-a-week approach allowed us to understand the epidemiology of MDR GNB, to timely detect new clones and institute contact precautions, and to assess risk factors. Collection of these data can be an important tool to optimize antimicrobials use and control the emergence and dissemination of resistances in NICU
Impact of Candida species colonization and azoles resistance in a neonatal intensive care unit
Get PDFBackground: Candida species are among the top 10 most frequently isolated nosocomial bloodstream pathogens in Europe. In particular, in neonatal intensive care units (NICUs) Candida infections are an emerging concern because of the increasing incidence, the related high morbidity and mortality rates reported. Moreover, the epidemiology of Candida infection rapidly changed in these years leading to the selection of less sensitive strains and species. Surveillance studies are mandatory to identify the local distribution of species, their antifungal susceptibility profiles and the emergence of resistance strains.
Material/methods: From December 2012 we performed a cohort prospective surveillance study in our NICU, collecting weekly nasal and rectal swabs. Swabs were placed on Sabouraud agar. Candida growth on agar plates was confirmed by microscopic observation. Furthermore, Candida spp. was identified through Candida chromogenic agar (Candida chromogenic agar, Laboratorios Conda) and API® 20C AUX (Biomérieux). The first isolated non-C.albicans Candida (NCAC) species from colonized patients were tested with the main antifungal agents (YeastOne® Y010 Thermo Fisher Scientific) and the obtained MIC values were read according to CLSI.
Results: From December 2012 to June 2016 we enrolled 874 neonates and analyzed respectively 2014 nasal and rectal swabs. 20/2014 (0,99%) of nasal swabs and 128/2014 (6,35%) of rectal swabs tested positive for Candida spp. The species distribution is showed in the Graph 1. 89/874 (10,18%) neonates tested positive at least in one swab. 59 isolates of NCAC species were tested with the main antifungal agents. All the tested strains were susceptible to echinocandins and amphotericin B. The susceptibility patterns for azoles are shown in the Table 1. Conclusions: Our study confirm the rule of surveillance in the prevention and control of Candida spp. healthcare related infections especially in an high risk ward such as NICU. In particular, in our NICU fluconazole prophylaxis is administered according to standard protocols from 2009.Antifungal susceptibility testes allowed to identify resistant and mutant strains whom acquired resistance so to obtain both clinical and epidemiological data promptly
The role of choline metabolism in peripheral nervous system myelination
No full textMyelination of axons increases the efficiency of the nervous system by increasing the conductivity of the action potentials. Peripheral demyelinating diseases are prevalent disorders caused by impairments in Schwann cell myelination with no currently available cure. The objective of this thesis is to describe the role of choline metabolism in peripheral nervous system myelination. The myelin sheath is comprised of a large percentage of phospholipids and choline is the major precursor to many of its lipid components. The choline-phosphatidylcholine pathway generates phosphoinositide which important in lipid biosynthesis as well as intracellular signaling and endomembrane trafficking. The imbalance of phosphoinositide levels, particularly PI(3,5)P2, has been implicated in abnormal myelin formation. In fact, pathways regulating phosphoinositide levels are impaired in multiple peripheral demyelinating diseases underscoring the importance of understanding the role of choline metabolism in Schwann cell myelination. Choline also has regulatory effects on DNA and histone methylations, making it an important component for epigenetic modifications in Schwann cells. By gaining a better understanding of the molecular mechanisms that contribute to demyelinating disorders, specifically related to choline metabolism, we can develop effective therapeutic treatments.M.S.Includes bibliographical reference
Seismic stratigraphy and marine magnetics of the Naples Bay (Southern Tyrrhenian sea, Italy): the onset of new technologies in marine data acquisition, processing and interpretation
Get PDFSeismic stratigraphy and marine magnetics in the case histories of the Somma-Vesuvius volcanic complex, Phlegrean Fields offshore and Ischia and Procida islands offshore (Naples Bay, Southern Tyrrhenian sea) are here discussed. Detailed geo-volcanologic setting of these areas is presented to give a better framework of the presented data. Seismo-stratigraphic techniques and methodologies are discussed, focussing, in particular, on the Naples area, where the Quaternary volcanic activity prevented the application of classical stratigraphic concepts, due to the occurrence of interlayered sedimentary sequences and intervening volcanic bodies (volcanites and volcaniclastites). The onset of new technologies in marine data acquisition, processing and interpretation is also discussed taking into account some historical aspects
