1,720,965 research outputs found
Accuracy of different methods for susceptibility testing of gentamicin with KPC carbapenemase-producing Klebsiella pneumoniae
Get PDFPerformance of Vitek2, Etest, and TREK broth microdilution (BMD) panels was evaluated versus reference CLSI BMD for gentamicin susceptibility testing with 57 bloodstream isolates of KPC-producing Klebsiella pneumoniae. Compared with reference BMD, the Essential Agreement and Categorical Agreement for TREK panels, Vitek2, and Etest were 91.2%, 31.6%, and 61.4%, respectively, and 86%, 21%, and 52.6%, respectively. Four very major discrepancies occurred with Vitek2. In these 4 strains, gentamicin resistance was associated with the presence of an armA aminoglycoside resistance determinant
OXA-372, a novel carbapenem-hydrolysing class D β-lactamase from a Citrobacter freundii isolated from a hospital wastewater plant
No full textpeer reviewedObjectives: The objective of this study was to characterize a novel class D carbapenemase, named OXA-372, identified in a carbapenem-resistant Citrobacter freundii strain (Cfr-FI-07) isolated from a hospital wastewater plant in central Italy. Methods: Cfr-FI-07 was isolated using a selective chromogenic medium for carbapenem-resistant Enterobacteriaceae. Carbapenemase production was confirmed by spectrophotometric assay. WGS was carried out using an Illumina MiSeq platform. The functional profile of OXA-372 was investigated by expression of the cloned gene in Escherichia coli and by analysis of kinetic parameters of the purified enzyme. Results: C. freundii Cfr-FI-07 produced carbapenemase activity, but tested negative for common carbapenemase genes. WGS confirmed the absence of known carbapenemase genes and revealed the presence of a novel class D b-lactamase (DBL) determinant, named blaOXA-372, encoding a protein distantly related to other DBLs. In E. coli, production of OXA-372 conferred resistance to penicillins, including temocillin, and reduced susceptibility to carbapenems, while susceptibility to expanded-spectrum cephalosporins was virtually unaffected. This substrate specificity was confirmed by kinetic characterization of the purified enzyme, which exhibited high catalytic efficiencies for carbapenems (kcat/KM values ≥0.22 s2-1.μM-1). The blaOXA-372 genewas associated with a genetic platform of original structure consisting of a Tn402/Tn5053 hybrid transposon derivative, named Tn6255, inserted into a TnPa38-like transposon, named Tn6256, located on an IncA/C-IncN plasmid of approximately 140 kb. Conclusions: OXA-372 is a novel class D carbapenemase, belonging to a new lineage of DBLs, encoded by a gene associated with mobile elements. Functional properties revealed similarities, but also some differences, compared with other class D carbapenemases. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved
Automazione: nuovi scenari in microbiologia clinica. Esperienza dell'AOU Careggi di Firenze.
No full textL'automazione è un processo personalizzabile che può variare da pochi passi del percorso analitico ad un quadro di automazione totale di laboratorio (TLA).
Sebbene l'automazione abbia ottenuto, a partire dalla fine degli anni ’90, una vasta diffusione in determinate aree di medicina di laboratorio, la microbiologia clinica sembrava essere esclusa da questa tendenza perché si riteneva che il settore fosse troppo complesso, che fosse impossibile riprodurre la capacità critica del dirigente, che i costi fossero troppo elevati e gli spazi troppo ridotti. Negli ultimi anni però un'ondata di automazione è arrivata anche nei laboratori di microbiologia. Molti i fattori che hanno contribuito a far cambiare atteggiamento a proposito dell’automazione nella microbiologia clinica, tra questi la carenza di personale addestrato e la richiesta di migliorare la qualità ed ottenere risultati tempestivi. Tra le principali tecnologie che hanno permesso o permetteranno il passaggio al TLA sicuramente sono da ricordare i tamponi con soluzione di trasporto liquida, che hanno iniziato a semplificare il processo, permettendo una maggiore standardizzazione. Questo associato all’avvento di immagini digitali ad altissima definizione ed all’evoluzione della robotica ha permesso alla microbiologia di muovere i primi passi verso l’automatizzazione.
Negli ultimi anni nel laboratorio di microbiologia e virologia di Careggi, (Firenze) si è assistito, coerentemente con i dati riportati in letteratura, sia all’insistente richiesta di riduzione dei tempi di refertazione che alla riduzione del personale. Per far fronte a questo nuovo scenario il laboratorio ha adottato una soluzione di TLA. In questo lavoro ci proponiamo, ad un anno dall’istallazione del sistema WASP-LAB COPAN DIGNOSTICS, di descrivere come è stato modificato il flusso di lavoro nel laboratorio e di valutare quali siano i punti forti e quali le debolezze di questa nuova organizzazione, con particolare attenzione alla possibilità di ridurre il TAT (turn around time) e di migliorare l’accuratezza nella gestione del campione.
Abbiamo inoltre valutato le prestazioni di un nuovo prototipo, proposto dal gruppo del Prof Mecocci del Dipartimento di ingegneria informatica e matematica dell’Università degli studi di Siena, che si propone l’obiettivo di leggere in modo completamente automatico le piastre su terreno cromogeno grazie all’immagine digitale fornita dal TLA.
L’impatto del TLA sulla routine di laboratorio è stato notevole soprattutto in termini di: organizzazione degli spazi, riorganizzazione del flusso di lavoro e gestione dei protocolli. Questi cambiamenti hanno portato ad una maggiore fluidità nello svolgimento delle attività routinarie oltre che ad una riduzione del TAT. Infine grazie, anche, al collegamento della catena con il sistema Lis, che permette di tenere in memoria lo storico del paziente, si è passati alla gestione dei campioni non più per materiale ma per paziente ottenendo il miglioramento dell’efficienza del servizio e in molti casi la riduzione del TAT.
Per quanto riguarda la valutazione del programma fornito dal gruppo di Siena si è osservata una concordanza dal 100% nell’attribuzione dei negativi mentre alcune difficoltà si sono riscontrate nell’identificazione di contaminanti cutanei o di alterazioni del terreno. Sulle alte cariche il problema del sistema è essenzialmente quello di non riuscire ad identificare le colture polimicrobiche. Potrebbe essere, per tanto, preso in considerazione come sistema di pre-screeaning per i campioni negativi
Large nosocomial outbreak of colistin-resistant, carbapenemase-producing klebsiella pneumoniae traced to clonal expansion of an mgrb deletion mutant
Get PDFWe describe a large hospital outbreak (93 bloodstream infections) of colistin-resistant Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae isolates which was mirrored by increased colistin consumption. The outbreak was mostly traced to the clonal expansion of an mgrB deletion mutant of an ST512 strain that produced KPC-3
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Extraction of high level visual features for the automatic recognition of UTIs
No full textUrinary Tract Infections (UTIs) are a severe public health problem, accounting for more than eight million visits to health care providers each year. High recurrence rates and increasing antimicrobial resistance among uropathogens threaten to greatly increase the economic burden of these infections. Normally, UTIs are diagnosed by traditional methods, based on cultivation of bacteria on Petri dishes, followed by a visual evaluation by human experts. The need of achieving faster and more accurate results, in order to set a targeted and sudden therapy, motivates the design of an automatic solution in place of the standard procedure. In this paper, we propose an algorithm that combines a “bag–of–words” approach with machine learning techniques to recognize infected plates and provide the automatic classification of the bacterial species. Preliminary experimental results are promising and motivate the introduction of a visual word dictionary with respect to using low level visual features
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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