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Valutazione dell’attività antimicrobica di un sistema decontaminante a base di perossido d’idrogeno. Risultati in vitro e su riunito odontoiatrico
No full textÈ stato riscontrato che l’acqua in circolo nei riuniti odontoiatrici può raggiungere una concentrazione microbica molto maggiore
della carica batterica consentita per legge nell’acqua potabile. La contaminazione del circuito idrico del riunito si ritiene imputabile principalmente
a microrganismi provenienti dalla rete idrica e a microrganismi del cavo orale, che possono contaminare per capillarità o per ritrazione il
riunito (infezione crociata paziente-paziente). Lo scopo di questo lavoro è stato testare, attraverso metodiche di analisi microbiologica dell’acqua,
l’efficacia di un sistema di controllo della contaminazione batterica che effettua l’addizione in continuo di H2O2 all’acqua del circuito idrico, e
confermare la validità di un sistema automatico di disinfezione sempre a base di perossido d’idrogeno. Sono stati testati microrganismi aerobi isolabili
dall’acqua in ingresso nel riunito (Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Streptococcus faecalis, Candida albicans,
Candida parapsilopsis, Candida glabrata, Candida krusei, Candida tropicalis, Mycobacterium marinum) e batteri a crescita anaerobia che possono
derivare da fenomeni di contaminazione paziente-paziente (Prevotella intermedia, Actinobacillus actinomycetemcomitans, Porphyromonas
gingivalis, Micromonas micros, Tannerella forsythensis, Fusobacterium nucleatum, Veillonella parvula). I risultati ottenuti indicano un’eccellente
attività antibatterica verso Mycobacterium marinum, C. albicans e i microrganismi ripetutamente isolati nei riuniti. La possibilità di aggiungere in
continuo il disinfettante a bassa concentrazione (300 o 600 ppm) ha evidenziato un’eccellente attività anche su B. atrophaeus, microrganismo di
difficile inattivazione a causa della tendenza a produrre endospore
Molecular identification of bacteriocins produced by Lactococcus lactis dairy strains and their technological and genotypic characterization
No full textIn this study, the bacteriocins produced by ten Lactococcus lactis subsp. lactis strains, previously isolated from raw milk and traditional Sardinian cheeses, were identified by targeting and sequencing the bacteriocin encoding genes. The inhibitory activity against different food borne and spoilage bacteria, and the technological and genotypic characteristics of the bacteriocinogenic L.lactis strains were also analysed. The presence of the nisin structural gene was confirmed for all L.lactis strains. Three strains were shown to harbour the Lactococcins B structural gene. The sequences of PCR products for the nisin gene from the ten bacteriocinogenic strains were compared with that of L. lactis strain ATCC 11454 (nisin A producer strain). Differences were observed in strain 6LS5 indicating its ability to produce the nisin Z variant. Five strains presented a wider inhibitory spectrum resulting in activity towards Pseudomonas aeruginosa and all the Bacillus, Listeria, Staphylococcus and Clostridium strains tested. High β-galactosidase and moderate aminopeptidase activities, that promote the desirable flavours in cheese, were detected in the majority of the strains. Rep-PCR with primer (GTG)5 revealed high diversity among the strains and allowed discrimination at both interspecific and intraspecific level. The autochthonous bacteriocinogenic isolates from Sardinian dairy products described in this work may potentially find application as starter, co-starter or protective adjunct cultures in the manufacturing of cheeses
Azole resistance and ERG11 464 polymorphism in oral Candida albicans clinical strains isolated in Sardinia
No full textThe in vitro activity of three different azoles (fluconazole, FLC, voriconazole, VRC and ketoconazole, KTC)
was determined and correlated with the single nucleotide polymorphisms (SNPs) in a “hot spot” region of the ERG11
gene in a collection of 52 arbitrarily selected C. albicans strains isolated from Sardinian subjects with oropharyngeal candidiasis.
Among the strains evaluated, 23.1% were resistant, 9.6% Sensible Dose Dependent (SDD) and 67.3% susceptible
to FLC. Among the FLC resistant strains, 83.3% were also cross-resistant to VRC (10/12) and 66.6% to KTC (8/12). The
homozygous point mutation G464S was only detected in four out of five SDD to fluconazole strains. These data showed
that the resistance of Candida albicans to azoles and the mutation at codon 464 of ERG11 are not associated. In addition
the results also indicate a high prevalence of azole-resistant and cross resistant strains among these patients
Evaluation of Antimicrobial-Antibiofilm Activity of a Hydrogen Peroxide Decontaminating System Used in Dental Unit Water Lines
No full textA dental unit water line (DUWL) equipped with a device designed to automatically and continually flush a bacteriostatic solution of hydrogen peroxide (WHE) and a discontinuous disinfecting system (BIOSTER) was evaluated. In the first instance a preliminary sensitivity test on a large number of microorganisms (bacteria and fungi) was tried with a H(2)O(2) range from 100 to 800 ppm. The bacteria frequently reported in DUWL (including Pseudomonas spp, Streptococcus spp., Staphylococcus spp., E. coli) and some periodontal pathogens showed a minimum inhibitory concentration from 100 to 300 H(2)O(2 )ppm (also including M. marinum and C. albicans). However, H(2)O(2) did not show any inhibitory effects against: A. actinomycetemcomitans, C. glabrata C. parapsilos, F. nucleatum, M. micros. In a second step, the DUWL was experimentally infected with S. faecalis, E. coli, P. aeruginosa, S. aureus. After disinfection steps with 3% H(2)O(2), the inhibitory effect on planktonic forms and on sessile biofilm was measured. In a third step, the count of 16S rRNA gene copies by real time PCR at different points of the DUWL described an accrue of bacterial slime in "hot spot" regions characterized by irregular/slow water flux (valves, elbows). However these results suggest that hydrogen peroxide is not only able to inhibit bursts of planktonic bacteria inside the DUWL, but that it could also be effective against sessile biofilm containing heterotrophic microorganisms derived from domestic water line contamination. In addition some oral pathogens could be contaminating and surviving in DUWL
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
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