1,721,112 research outputs found
Genetic diversity of human isolates of Mycobacterium bovis assessed by Spoligotyping and Variable-Number-Tandem-Repeat genotyping
No full textA collection of clinical isolates including 9 Mycobacterium bovis bacille Calmette-Guérin (BCG), 37 M. bovis and 1 isolate identified as M. bovis/caprae intermediate, recovered from humans in Tuscany, Italy, from 1990 to 2009, was genotyped by spoligotyping and Variable Number Tandem Repeat (VNTR) typing. Spoligotyping detected 15 unique profiles; the "BCG-like" SIT482/SB0120 spoligotype was largely prevalent accounting for 63.8% of isolates. VNTR typing, based on the 15 VNTR loci commonly tested for Mycobacterium tuberculosis, detected 29 unique profiles; only 8 VNTR loci (VNTR 43, MIRU 04, QUB-11b, ETR-A, VNTR 47, MIRU 31, QUB-26 and VNTR 53) provided a satisfactory allelic diversity in the VNTR analysis. Combined together, spoligotyping and VNTR typing yielded 33 unique patterns and 5 clusters including a total of 19 isolates. Clustered isolates, further typed for additional 9 VNTR loci, finally yielded 3 distinct clusters including 3 M. bovis BCG isolates each, and 1 cluster of 6 M. bovis isolates. Minimum spanning tree analysis showed that, in spite of the many distinct VNTR profiles, most M. bovis isolates displayed a high phylogenetic proximity, due to the variation of a single VNTR allele, thus indicating that the population of human M. bovis isolates in our setting is relatively homogeneous and conserved
Impact of immigration on tuberculosis in a low-incidence area of Italy: a molecular epidemiology approach
No full textP>The effects that immigration might have on the epidemiology of tuberculosis (TB) in a low-incidence area of Italy was investigated by determining, in autochthonous and immigrant TB patients, the molecular characteristics of the Mycobacterium tuberculosis complex (MTBC) isolates, which may provide information on their phylogeographical origin. A total of 1080 MTBC strains, collected during a 4-year period in Tuscany from 614 Italian-born and 466 foreign-born patients, were genotyped by spoligotyping and assigned to the different phylogeographical lineages that constitute the MTBC. The autochthonous Euro-American phylogeographical lineage, which includes the spoligotype families T, Haarlem, Latin American-Mediterranean (LAM), S and X, was highly prevalent among Italian-born patients, with a total of 477 cases (77.7%), and foreign-born TB patients, with a total of 270 cases (57.9%); 24 Italian-born (3.9%) and 141 foreign-born (30.3%) TB cases were due to MTBC genotypic families associated with distant geographical areas, i.e. East African-Indian (EAI), Beijing, Central Asian (CAS), and Mycobacterium africanum. Strains of Mycobacterium bovis and strains of undefined genotype, which are all considered together, as it is not possible to assign a specific geographical origin, accounted for 113 (18.4%) Italian cases and 55 (11.8%) foreign-born cases. A total of 79 Italian TB cases (12.9%) have been attributed to transmission from immigrants to the local population. No significant contribution to drug resistance appeared to be associated with imported MTBC strains. It is concluded that, at present, the overall impact of imported TB on public health in the low-incidence study area is relatively modest and of the same order as in other western countries
Delayed diagnosis of disseminated mycobacterium genavense infection in a human immunodeficiency virus-negative young woman
No full textWe report here a case of Mycobacterium genavense-disseminated infection in a human immunodeficiency virus-negative young patient under immunosuppressive treatment for autoimmune chronic hepatitis type I. The diagnosis was achieved thanks to the detection of Mycobacterium genavense-specific DNA in a hepatic biopsy embedded in paraffin for histologic examination 2 years before. Copyright © 2011 by National Foundation for Infectious Diseases
Molecular analysis of clinical isolates of Mycobacterium bovis recovered from humans in Italy
No full textIn order to achieve a better knowledge of Mycobacterium bovis epidemiology in Italy, 42 clinical isolates from humans were genotyped. Predominant molecular patterns were found in one cluster of 15 isolates sharing spoligotype (ST482), variable-number tandem repeat (VNTR), and IS6110-based restriction fragment length polymorphism (one 1.9-kb band) profiles and in two clusters of 6 and 3 Mycobacterium bovis BCG isolates differing by one VNTR character. The remaining 18 isolates yielded unique profiles. Our results confirm the potential utility of spoligotyping and VNTR typing as a major typing system of M. bovis isolates
Mutations in mutT genes of Mycobacterium tuberculosis isolates of Beijing genotype
No full textMissense alterations in genes mutT4 and mutT2, which encode DNA repair enzymes, were sequenced from 30 clinical isolates of Mycobacterium tuberculosis of Beijing genotype, mostly from patients with primary tuberculosis, to evaluate their contribution to anti-mycobacterial drug resistance. The mutation Arg to Gly at codon position 48 (CGG to GGG) of mutT4 was found in 21 isolates; of these, 16 isolates also harboured the mutation Gly to Arg at position 58 (GGA to CGA) of mutT2. No statistically significant association was found between mutT4 and mutT2 mutations, and drug resistance. Furthermore, no mutations in mutT4 or mutT2 were found in any of 24 isolates resistant to multiple drugs, nor in 28 anti-mycobacterial drug-susceptible isolates of different genotypes. These data confirm that the polymorphism of mutT genes is characteristic and unique to the Beijing phylogenetic lineage. The mutator phenotype does not appear to increase prevalence of drug resistance, but further studies are required to investigate the mutation rates of Beijing isolates in response to drug exposure
IS6110-RFLP e spoligotyping di ceppi di Mycobacterium tuberculosis isolati in Toscana nel 2002
No full textLa recente scoperta di elementi trasponibili in Mycobacterium tuberculosis, in particolare la sequenza di inserzione IS6110, ha consentito l'allestimento di un metodo di tipizzazione molecolare basato sul polimorfismo della lunghezza dei frammenti di restrizione IS6110-specifici (IS6110-RFLP), che rappresenta la base per lo studio dell’epidemiologia molecolare della tubercolosi (TB). Nel presente lavoro si riporta la tipizzazione IS6110-RFLP di 249 ceppi di M. tuberculosis complex, isolati da altrettanti pazienti, che rappresentano pressoché la totalità degli isolati in Toscana nel corso dell’anno 2002.
L’analisi IS6110-RFLP ha consentito di individuare 225 profili di bandeggio unici e 56 ceppi (22.5%) che si presentavano in clusters di pochi elementi identici. In particolare, 19 clusters erano costituiti da 2 ceppi, 3 clusters da 3 ceppi, 1 cluster da 4 ceppi ed 1 cluster da 5 ceppi identici. Siccome si ritiene che i clusters comprendano i ceppi implicati in infezioni tubercolari di recente acquisizione, se ne deduce che in Toscana la trasmissione della TB è comparabile a quella dei Paesi a bassa incidenza di TB, anche se sono da segnalare sporadici episodi di microfocolai epidemici.
I ceppi sono stati inoltre sottoposti ad analisi “Spoligotyping”, una tecnica molecolare basata sul polimorfismo delle regioni spaziatrici (spacers) del locus DR (Direct Repeats) di M. tuberculosis che, sebbene dotata di un minor potere discriminativo rispetto alla tipizzazione IS6110-RFLP, consente l’individuazione dei ceppi della famiglia denominata Beijing o W, i cui membri stanno destando allarme a livello mondiale per le potenzialità di rapida diffusione, di maggior virulenza e di acquisizione di farmaco-resistenza multipla. L’analisi Spoligotyping dei 249 ceppi ha individuato 7 ceppi di genotipo Beijing/W, 5 dei quali isolati da pazienti immigrati, dimostrando così per la prima volta la loro presenza e diffusione anche in Italia. I 7 ceppi Beijing/W isolati in Toscana nel 2002 si sono rivelati comunque suscettibili ai farmaci anti-tubercolari di prima scelta
Missense alterations in mutT4 and mutT2 genes of clinical isolates of Mycobacterium tuberculosis of beijing genotype
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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
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