Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Development and implimentation of techniques for the determination of very low activities of radioactive trace elements in environmental samples

The aim of this PhD Thesis was the determination of very low concentrations of natural and artificial radioactive isotopes in environmental samples by means of gamma-spectroscopy techniques. Natural and artificial radioactive isotopes of low or higher specific activity are contained and can be detected in any environmental sample. Even when their specific activity is low, leading to negligible radiobiological significance, their detection is of interest in various applications, such as their use as tracers for environmental processes. In addition, improving the levels of detection of an isotope using a γ-spectroscopic apparatus, may allow the detection of the isotope in smaller volume samples without significant compromise on the accuracy of the measurement, which has obvious consequences in the design of the sampling. Since the background of a γ-spectroscopic apparatus is a factor determining the ability to detect low levels of radioactivity in a sample, its reduction is always highly desirable.In the framework of the Thesis the installation, study and use of the new Compton Suppression system (CSS), which was installed on the XtRa detector of the N.E.D. - N.T.U.A was carried out, aiming the reduction the continuous background of the detector and the improvement of the detection limits of the XtRa - CSS apparatus. The electronic set-up of the apparatus allows for the simultaneous collection of two spectra with a suppressed or not (unsuppressed) continuous background. In the framework of the study, a series of response factors were used, as referred in literature, through which the effect of various phenomena observed in the detection of photons by the Compton Suppression system was identified, and should be taken into account both during the calibration of the device, and during routine analyzes. As a result of this study, the optimal conditions for the detection of each isotope are proposed. The device was then calibrated experimentally but also using Monte Carlo simulation techniques for a series of source-to-detector geometries. For this purpose, it was necessary to modify the PENELOPE simulation code used in the N.E.D. - N.T.U.A in order to take into account both the true coincidence phenomenon during spectrum collection and to simulate a Compton Suppression system consisting of two independent detectors (primary detector and secondary detector or active shield) that communicate with each other.One of the main objectives of the Thesis was the detection of radioactive isotopes found at very low concentrations in environmental samples. For this purpose appropriate sampling techniques for atmospheric aerosols and liquid atmospheric precipitations and sample preparation were developed and a large number of samples were analyzed, mainly (a) contaminated samples due to the nuclear accidents in Chernobyl and Fukushima, (b) atmospheric aerosol and precipitation samples. From these analyzes it was possible to detect 241Am from the Chernobyl accident and a strong correlation with the 137Cs concentration was found. In addition, the use of the Compton Suppression System allowed for the detection of artificial radioactive isotopes due to the Fukushima accident in atmospheric aerosol and precipitation samples, in concentration of the order of a few tens of mBq/m3, as well as the detection of natural radioactive isotopes of earth and cosmic origin such as 210Pb, 7Be and 22Na – which is extremely difficult to detect because of its very low radioactivity, of 1 μBq/m3 – isotopes that are used in the literature as tracers for atmospheric processes.At N.E.D. - N.T.U.A the technique of neutron activation for the detection and quantification of a series of non-radioactive trace elements has been applied for many years. The XtRa - CSS apparatus was also used to detect more elements and to improve the detection limits of the method. In the framework of the Thesis, a series of irradiation-γ-spectroscopic analysis scenarios were examined, which, combined to the use of the XtRa - CSS apparatus, allowed for the detection of 15 elements and trace elements (Al, As, Au, Cu, Eu, Fe , Ga, K, La, Mg, Mn, Na, Sb, Sc, Zn) and improved the lower limits of detection up to 7 times compared to the past. In addition, the appropriate calibration coefficients were determined to allow the quantification of the above elements in environmental samples such as soil, fly ash, marine sediment and industrial slag.Η παρούσα Διδακτορική Διατριβή (Δ.Δ.) είχε ως αντικείμενο τον προσδιορισμό πολύ χαμηλών συγκεντρώσεων φυσικών και τεχνητών ραδιενεργών ισοτόπων σε περιβαλλοντικά δείγματα, με τεχνικές γ-φασματοσκοπίας. Όπως είναι γνωστό, φυσικά και τεχνητά ραδιενεργά ισότοπα, με χαμηλή ή υψηλότερη ειδική ραδιενέργεια περιέχονται και είναι δυνατό να ανιχνεύονται σε πάσης φύσεως περιβαλλοντικά δείγματα. Ακόμα και στην περίπτωση όπου, λόγω της χαμηλής ειδικής ραδιενέργειας των δειγμάτων, η ραδιοβιολογική σημασία των ισοτόπων είναι αμελητέα, η ανίχνευσή τους μπορεί να έχει ενδιαφέρον σε διάφορες εφαρμογές, όπως για παράδειγμα κατά τη χρήση τους ως ιχνηλάτες περιβαλλοντικών διεργασιών. Επιπλέον, η βελτίωση των επιπέδων ανίχνευσης ενός ισοτόπου από μία γ-φασματοσκοπική διάταξη, μπορεί να επιτρέψει την ανίχνευση του ισοτόπου σε δείγματα μικρότερου όγκου, χωρίς σημαντικό συμβιβασμό στην ακρίβεια της μέτρησης, κάτι που έχει προφανείς συνέπειες κατά το σχεδιασμό της δειγματοληψίας. Καθώς το υπόστρωμα μίας γ-φασματοσκοπικής διάταξης είναι ένας παράγοντας που καθορίζει την ικανότητα ανίχνευσης χαμηλών επιπέδων ραδιενέργειας σε ένα δείγμα, η μείωσή του είναι πάντα άκρως επιθυμητή. Στο πλαίσιο της Δ.Δ. έγινε η εγκατάσταση, μελέτη και αξιοποίηση του νέου συστήματος Compton Suppression (CSS), το οποίο εγκαταστάθηκε στον ανιχνευτή XtRa του Ε.Π.Τ. - Ε.Μ.Π., με στόχο τη μείωση του συνεχούς υποστρώματος του ανιχνευτή και τη βελτίωση των ανιχνευτικών δυνατοτήτων του ανιχνευτικού συστήματος XtRa - CSS. Η συγκρότηση της διάταξης επιτρέπει την ταυτόχρονη συλλογή δύο φασμάτων με μειωμένο (suppressed) ή όχι (unsuppressed) το συνεχές υπόστρωμα. Στο πλαίσιο της μελέτης που έγινε, χρησιμοποιήθηκαν μία σειρά από δείκτες, οι οποίοι αναφέρονται στη βιβλιογραφία, μέσω των οποίων διαπιστώθηκε η επίδραση των διαφόρων φαινομένων τα οποία παρατηρούνται κατά την ανίχνευση των γ-φωτονίων από το σύστημα, και πρέπει να λαμβάνονται υπόψη τόσο κατά τη διάρκεια της βαθμονόμησης της διάταξης, όσο και κατά τη διάρκεια αναλύσεων ρουτίνας. Ως αποτέλεσμα της μελέτης αυτής γίνεται πρόταση για τις βέλτιστες συνθήκες ανίχνευσης καθενός ισοτόπου ξεχωριστά. Στη συνέχεια, η διάταξη βαθμονομήθηκε πειραματικά αλλά και με χρήση τεχνικών προσομοίωσης Monte Carlo για μία σειρά από γεωμετρίες πηγής-ανιχνευτή. Για το σκοπό αυτό χρειάσθηκε να τροποποιηθεί ο κώδικας προσομοίωσης PENELOPE που χρησιμοποιείται στο Ε.Π.Τ. - Ε.Μ.Π., ώστε να λαμβάνει υπόψη τόσο το φαινόμενο της πραγματικής σύμπτωσης φωτονίων (true coincidence) κατά τη διάρκεια συλλογής του φάσματος, όσο και για να προσομοιώνει ένα σύστημα Compton Suppression, που αποτελείται από δύο ανεξάρτητους ανιχνευτές (πρωτεύων ανιχνευτής και δευτερεύων ανιχνευτής ή ενεργητική θωράκιση) οι οποίοι επικοινωνούν μεταξύ τους.Από τους βασικούς στόχους της Δ.Δ. ήταν η ανίχνευση ραδιενεργών ισοτόπων τα οποία βρίσκονται σε πολύ χαμηλές συγκεντρώσεις σε περιβαλλοντικά δείγματα. Για το σκοπό αυτό αναπτύχθηκαν κατάλληλες τεχνικές δειγματοληψίας ατμοσφαιρικού αεροζόλ και υγρών ατμοσφαιρικών κατακρημνίσεων και προετοιμασίας δείγματος και αναλύθηκε μεγάλο πλήθος δειγμάτων, κυρίως (α) δείγματα που έχουν ρυπανθεί από τα πυρηνικά ατυχήματα στο Chernobyl και στη Fukushima, (β) δείγματα ατμοσφαιρικού αεροζόλ και υγρών κατακρημνίσεων. Από τις αναλύσεις αυτές κατέστη δυνατή η ανίχνευση στο έδαφος 241Am από την εποχή του Chernobyl και η συσχέτισή του με τη συγκέντρωση του 137Cs. Επίσης, κατέστη δυνατή η ανίχνευση στο ατμοσφαιρικό αεροζόλ και στις υγρές κατακρημνίσεις ισοτόπων εξαιτίας του ατυχήματος στη Fukushima σε επίπεδα λίγων δεκάδων μBq/m3, αλλά και φυσικών ραδιενεργών ισοτόπων γήινης και κοσμικής προέλευσης, όπως το 210Pb, το 7Be αλλά και το 22Na – το οποίο ανιχνεύεται με εξαιρετική δυσκολία, λόγω της χαμηλής ραδιενέργειάς του, της τάξης του 1μBq/m3 – ισότοπα τα οποία χρησιμοποιούνται στη βιβλιογραφία ως ιχνηλάτες ατμοσφαιρικών διεργασιών. Στο Ε.Π.Τ. - Ε.Μ.Π. εφαρμόζεται εδώ και πολλά χρόνια και η τεχνική της νετρονικής ενεργοποίησης για την ανίχνευση και τον ποσοτικό προσδιορισμό μίας σειράς μη ραδιενεργών ιχνοστοιχείων. Η ανιχνευτική διάταξη XtRa - CSS αξιοποιήθηκε, με στόχο την ανίχνευση περισσοτέρων στοιχείων και τη βελτίωση των επιπέδων ανίχνευσής τους. Στο πλαίσιο της Δ.Δ., η εφαρμογή μίας σειράς σεναρίων ακτινοβόλησης – γ-φασματοσκοπικής ανάλυσης, σε συνδυασμό με τη χρήση του συστήματος XtRa - CSS, οδήγησε στην ανίχνευση 15 στοιχείων και ιχνοστοιχείων (Al, As, Au, Cu, Eu, Fe, Ga, K, La, Mg, Mn, Na, Sb, Sc, Zn) και βελτίωσε τα κατώτερα επίπεδα ανίχνευσης έως και 7 φορές σε σχέση με το παρελθόν. Επιπλέον, προσδιορίσθηκαν οι κατάλληλοι συντελεστές βαθμονόμησης που επιτρέπουν τον ποσοτικό προσδιορισμό των παραπάνω στοιχείων σε περιβαλλοντικά δείγματα όπως: χώμα, ιπτάμενη τέφρα, θαλάσσιο ίζημα και βιομηχανική σκωρία

Efficiency calibration of a semiconductor detector for the quantification of the radioactive isotope Be-7 concentration in the atmospheric aerosol using Monte Carlo simulation Techniques

262 σ.Αντικείμενο της παρούσας Δ.Ε. είναι η βελτίωση της μεθοδολογίας προσδιορισμού της συγκέντρωσης του ισοτόπου κοσμικής προέλευσης Be-7 στην ατμόσφαιρα, η οποία ακολουθείται στο Εργαστήριο Πυρηνικής Τεχνολογίας του ΕΜΠ. Το ισότοπο αυτό απαντάται σε πολύ χαμηλές συγκεντρώσεις (<10mBq/m3). Στόχος της επιδιωκόμενης βελτίωσης είναι η καλύτερη μελέτη της κύμανσης της συγκέντρωσης του συγκεκριμένου ισοτόπου στην ατμόσφαιρα και μάλιστα σε μικρή κλίμακα χρόνου (μερικές ώρες). Για το λόγο αυτό εισάγεται νέα γεωμετρία ανάλυσης φίλτρων αέρα η οποία βαθμονομείται με χρήση των τεχνικών προσομοίωσης Monte Carlo (κώδικας PENELOPE).Η νέα γεωμετρία συγκρίνεται με την ισχύουσα και καταδεικνύονται τα πλεονεκτήματα της, ενώ εφαρμόζεται και σε ημερήσιο κύκλο δειγματοληψιών ατμοσφαιρικού αέρα από όπου αποδεικνύεται η δυνατότητα ανίχνευσης της κύμανσης της συγκέντρωσης του ισοτόπου στα πλαίσια μίας ημέρας. Τέλος, γίνεται προσπάθεια προσδιορισμού του ισοτόπου στο βρόχινο νερό.The subject of this diploma thesis is the improvement of the method used in the Nuclear Engineering Department of NTUA (National Technical University of Athens) to measure the concentration of the cosmogenic isotope Be-7. This isotope is detected in very low concentrations in the atmospheric air (<10mBq/m3). The aim of this improvement is the more efficient detection of the concentration variability of Be-7 in the atmospheric aerosol, especially during a short period of time (a few hours). A new geometry for the filters used in the atmospheric air sampling was introduced. The efficiency calibration for this geometry and the XtRa detector of the department is carried out using Monte Carlo simulation techniques (PENELOPE code). The new geometry is compared to the old one and the results obtained show the advantages of this new geometry. In addition, the new geometry is applied to a series of consequent air sampling during one day (24 hours). The results of these sampling prove that the new geometry gives the ability to detect the concentration variation during the short period of 24 hours. Finally, an attempt to detect the isotope Be-7 in rain water was conducted.Μαρίλια Ι. Σάββ

Determination of true coincidence correction factors using Monte-Carlo simulation techniques

Aim of this work is the numerical calculation of the true coincidence correction factors by means of Monte-Carlo simulation techniques. For this purpose, the Monte Carlo computer code PENELOPE was used and the main program PENMAIN was properly modified in order to include the effect of the true coincidence phenomenon. The modified main program that takes into consideration the true coincidence phenomenon was used for the full energy peak efficiency determination of an XtRa Ge detector with relative efficiency 104% and the results obtained for the 1173 keV and 1332 keV photons of 60Co were found consistent with respective experimental ones. The true coincidence correction factors were calculated as the ratio of the full energy peak efficiencies was determined from the original main program PENMAIN and the modified main program PENMAIN. The developed technique was applied for 57Co, 88Y, and 134Cs and for two source-to-detector geometries. The results obtained were compared with true coincidence correction factors calculated from the "TrueCoinc" program and the relative bias was found to be less than 2%, 4%, and 8% for 57Co, 88Y, and 134Cs, respectively

Monitoring of 7Be atmospheric activity concentration using short term measurements

The activity concentration of 7Be in atmospheric aerosol can exhibit seasonal variations due to various physical processes taking place in the troposphere and stratosphere, as well as due to solar activity. An investigation of these variations has been carried out at the Nuclear Engineering Department of the National Technical University of Athens over a two year period (3/2008-4/2010). In the framework of this study, sampling and analysis methods were appropriately selected to allow for the observation of short-term 7Be air activity concentration variations, using a 4-hour sampling interval, while taking in consideration type A and type B uncertainties introduced in the measurements. In order to study the role of precipitation in surface air 7Be activity concentration variations, a procedure for collecting and analyzing rainwater was developed. The techniques used in the present study allowed for the observation of seasonal and diurnal 7Be concentration variations, as well as correlations between 7Be activity concentration and the meteorological parameters of air temperature and relative humidity

Long Term Neutron Activation in JET DD Operation

In the 2019 C38 Deuterium-Deuterium campaign at JET several different ITER-relevant materials and dosimetry foils were irradiated in a specially designed long-term irradiation station located inside the vacuum vessel with the purpose of testing the activation of ITER materials by fusion neutrons. The samples were exposed to a neutron fluence of 1.9E14 n/cm2 during JET discharges performed in the experimental campaign over a period of 5 months. Gamma ray spectroscopy measurements were performed on irradiated samples to determine the activation of different long-lived isotopes in the samples. Monte Carlo computational analysis was performed to support the experiment by using the measured neutron yield and irradiation time. In this paper we focus on the computational analysis of the dosimetry foils that are used in order to measure the local neutron energy spectrum and flux. The foils were chosen to cover different neutron energies: thus Yttrium and some of the Nickel and Cobalt reactions were used to determine the Deuterium-Tritium fusion fraction, while Scandium and Iron and some of the Nickel and Cobalt reactions were used for comparison of the computed activity with the experimental measurements. The obtained C/E values show a reasonably good agreement between calculated and measured activity, thus validating the computational methodology and providing the basis for the analysis of the ITER-relevant materials and future experiments performed at JET in the Deuterium-Tritium campaign

Consistency test of coincidence-summing calculation methods for extended sources

An internal consistency test of the calculation of coincidence-summing correction factors FC for volume sources is presented. The test is based on exact equations relating the values of FC calculated for three ideal measurement configurations. The test is applied to a number of 33 sets of FC values sent by 21 teams. Most sets passed the test, but not the results obtained using the quasi-point source approximation; in the latter case the test qualitatively indicated the magnitude of the bias of FC. © 2019 Elsevier Lt