1,720,961 research outputs found
Characterization of plasmids encoding extended-spectrum β-lactamases (ESBLs) and QnrS1 in Avian Pathogenic Escherichia coli (APEC) isolated from commercial poultry flocks in Italy.
No full textAvian pathogenic Escherichia coli (APEC) cause infections with high morbidity and mortality in poultry flocks. The aim of this study was to characterize the mobilizable pool mediating resistance to cephalosporins and fluoroquinolones in APEC collected in Italy between 2008 and 2012.
Non-repetitive APEC from turkeys (n=109), broilers (n=98) and layers (n=22) were examined. Isolates resistant to third-generation cephalosporins were screened for presence of blaTEM, blaSHV, blaCTX-M and blaCMY-2 and for chromosomal ampC promoter mutations, while all isolates were tested by PCR for all known plasmid-mediated quinolone resistance (PMQR) genes. ESBL/AmpC or PMQR-harboring plasmids were typed by traditional typing methods.
Twenty-eight (12%) isolates displayed resistance to third-generation cephalosporins either mediated by mutations leading to chromosomal ampC overproduction (n=10) or by the following plasmid/gene combinations: IncI1/ST26/blaSHV-12 (n=1), IncI1/ST3/blaCTX-M-1 (n=7), IncI1/ST26/blaCTX-M-1 (n=1), IncI1/ST36/blaCTX-M-1 (n=2), IncI1/STnew/blaCTX-M-1 (n=1), IncN/blaCTX-M-1 (n=1), IncI1/ST26/blaCTX-M-2 (n=1), IncFII/blaCTX-M-14 (n=1), IncK/blaCTX-M-14 (n=1), IncI1/ST26/blaCMY-2 (n=1) and IncK/blaCMY-2 (n=1). Plasmids measured approximately 40 to 200 kb and mainly exhibited different RFLP profiles. Sixty (26%) and 21 (9%) isolates displayed resistance to nalidixic acid and ciprofloxacin, respectively. qnrS1 was detected in two isolates on IncX2 and a non-typeable plasmid of ca. 30 and 40 kb, respectively.
The APEC population in Italian poultry harbours diverse ESBL-encoding genes and plasmids, often in association with fluroquinolone resistance. Interestingly, IncI1/ST26 plasmids were associated with four β-lactamases (SHV-12, CTX-M-1, CTX-M-2 and CMY-2), suggesting that this plasmid lineage is well adapted in APEC isolated from Italian poultry production. These findings underline the need to develop new strategies for prevention and therapy of multidrug-resistant APEC infections
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
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
High diversity of genes and plasmids encoding resistance to third-generation cephalosporins and quinolones in clinical Escherichia coli from commercial poultry flocks in Italy
Get PDFThe aim was to investigate occurrence and diversity of plasmid-mediated resistance to third-generation cephalosporins (3GC) and quinolones in clinical Escherichia coli from 200 industrial poultry farms across Italy. E. coli was isolated from colibacillosis lesions in turkeys (n = 109), broilers (n = 98) and layers (n = 22) between 2008 and 2012. 3GC-resistant isolates were screened for extended-spectrum and AmpC Î2-lactamase (ESBL/AmpC), while all isolates were tested for plasmid-mediated quinolone resistance (PMQR) genes. ESBL/AmpC- and PMQR-positive isolates were typed by pulsed-field gel electrophoresis and antimicrobial susceptibility testing, and their plasmids were characterised by replicon typing, multilocus sequence typing, restriction fragment length polymorphism and conjugation. EBSL/AmpC genes (blaCTX-M-1, blaCTX-M-14, blaCTX-M-2, blaSHV-12and blaCMY-2) were detected in 7%, 9% and 4% of isolates from turkeys, broilers and layers, respectively. We identified seven ESBL/AmpC-encoding plasmid types, usually conjugative (78%), with a marked prevalence of IncI1/pST3 plasmids carrying blaCTX-M-1. PMQR occurred less frequently among isolates from turkeys (0.9%) compared to those from broilers (5%) and layers (4%). The PMQR genes qnrS, qnrB19 and oqxA/B were located on three plasmid types and two non-typeable plasmids, mostly (85%) conjugative. ESBL/AmpC- and PMQR-positive isolates were genetically unrelated and 64% of them were additionally resistant to aminoglycosides, sulfonamides and tetracyclines. Our data show that 3GC- and quinolone-resistant clinical E. coli in Italian poultry production represent a highly diverse population often resistant to most antimicrobials available for poultry. These findings underline the crucial need to develop new strategies for prevention and control of colibacillosis
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
High-throughput sequencing of avian Infectious Laryngotracheitis virus (ILTV).
No full textBACKGROUND-AIM
Infectious laryngotracheitis (ILT) is an acute and highly contagious respiratory disease of chickens, caused by an alphaherpesvirus, named Infectious Laryngotracheitis virus (ILTV). Recently, full genome sequences of wild-type and vaccine strains have been analysed, but none was from Europe. The aim of this study was to determine and analyse the complete genome sequences of five Italian ILTV strains. Sequences were also compared to reveal the similarity of strains across time and to discriminate between wild-type and vaccine strains.
METHODS
Genomes of 3 ILTV field isolates from outbreaks occurred in Italy in 1980, 2007 and 2011, and 2 commercial chicken embryo origin (CEO) vaccines were sequenced using the 454 Life Sciences technology. Sequences were mapped on the reference sequence (Serva strain, GenBank accession no. HQ630064) using Roche gsMapper.
RESULTS
The length of the five ILTV genomes ranged from 153,650 bp to 153,662 bp. The comparison with the Serva genome showed that 35 open reading frames (ORFs) differed across the five ILTV genomes. Overall, 54 single nucleotide polymorphisms (SNPs) and 27 amino acid differences in 19 ORFs and 2 insertions of 9 and 3 nucleotides in two different ILTV genes were identified. Similarity among the wild-type and between the wild-type and the vaccine strains ranged from 99.95% to 99.98%. Phylogenetic analysis of the five strains and all the ILTV complete genomes available within the NCBI GenBank database showed a close relatedness of the three wild-type isolates, whereas the two vaccine strains grouped into separate clusters.
CONCLUSION
This study generated data on genomic variation among Italian ILTV strains revealing that the genome is well conserved across time and between wild-type and vaccine strains. Results of this study may contribute to the understanding of the molecular bases of ILTV pathogenicity and the genetic differences between wild-type and vaccine ILTV strains
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