Rapid tests for the detection of the Mycobacterium abscessus subsp. bolletii strain responsible for an epidemic of surgical-site infections in Brazil

A single strain of Mycobacterium abscessus subsp. bolletii, characterised by a particular rpoB sequevar and two highly related pulsed field gel electrophoresis patterns has been responsible for a nationwide outbreak of surgical infections in Brazil since 2004. In this study, we developed molecular tests based on polymerase chain reaction restriction-enzyme analysis (PRA) and sequencing for the rapid identification of this strain. Sequences of 15 DNA regions conserved in mycobacteria were retrieved from GenBank or sequenced and analysed in silico. Single nucleotide polymorphisms specific to the epidemic strain and located in enzyme recognition sites were detected in rpoB, the 3' region of the 16S rDNA and gyrB. The three tests that were developed, i.e., PRA-rpoB, PRA-16S and gyrB sequence analysis, showed 100%, 100% and 92.31% sensitivity and 93.06%, 90.28% and 100% specificity, respectively, for the discrimination of the surgical strain from other M. abscessus subsp. bolletii isolates, including 116 isolates from 95 patients, one environmental isolate and two type strains. The results of the three tests were stable, as shown by results obtained for different isolates from the same patient. In conclusion, due to the clinical and epidemiological importance of this strain, these tests could be implemented in reference laboratories for the rapid preliminary diagnosis and epidemiological surveillance of this epidemic strain.

Microsatellite variation and population genetic structure of a neotropical endangered Bryconinae species Brycon insignis Steindachner, 1877: implications for its conservation and sustainable management

Piabanha (Brycon insignis) is a freshwater fish species from the drainages in Southeastern Brazil. During the 1950s, it was an important economic and food resource for local populations, but dramatic and continuous environmental degradation seriously jeopardized the B. insignis populations in the region. Microsatellite markers were used to assess the genetic structure of wild populations of B. insignis and compare the genetic variability and integrity of the wild populations with a captive population. Samples of DNA from 208 specimens from geographically isolated populations were analyzed. Population genetic structure was investigated using F ST, R ST estimates as well as AMOVA. All five loci used in this study were polymorphic with observed heterozygosity ranging from 0.77 (± 0.15) to 0.88 (± 0.07) in the wild population and 0.90 (± 0.09) in the captive population and the allelic richness average were 7.56 (± 0.27) and 5.80 (± 1.02), respectively. Overall genetic differences were significantly partitioned among populations (F ST = 0.072, p = 0.034). Evidence of a genetic bottleneck was found in some of the wild populations, but especially in the captive population. The results showed that genetic variability still can be found in B. insignis populations which are currently structured possibly due to anthropic actions. The implications of these findings for the management and conservation of B. insignis populations are discussed.(AU)

Piabanha (Brycon insignis) é uma espécie de peixe de água doce oriunda de drenagens da região sudeste do Brasil. Durante os anos de 1950, esta espécie foi um importante recurso econômico para populações locais. Contudo, a intensa e contínua degradação ambiental afetou seriamente as populações de B. insignis na região. Marcadores microssatélites foram usados para avaliar a estrutura genética de populações selvagens de B. insignis e comparar a variabilidade genética e integridade das populações selvagens com uma população de cativeiro. Amostras de DNA de 208 espécimes de populações geograficamente isoladas foram analisadas. A estrutura populacional foi investigada usando-se estimadores de F ST e R ST bem como AMOVA. Todos os loci usados neste estudo foram polimórficos com heterozigosidades observadas variando de 0.77 (± 0.15) a 0.88 (± 0.77) em populações selvagens e 0.90 (± 0.09) na população de cativeiro e a riqueza alélica média foi de 7.56 (± 0.27) e 5.80 (± 1.02), respectivamente. A maioria das diferenças genéticas foi significativa entre populações (F ST = 0.072, p = 0.034). Evidências de efeito gargalo foram observadas em algumas populações selvagens e especialmente também na população de cativeiro. Os resultados do presente estudo mostraram que as populações de B. insignis ainda apresentam variabilidade genética e que estas populações estão atualmente estruturadas geneticamente provavelmente devido a ações antrópicas. As implicações destes achados para o manejo e conservação das populações de B. insiginis são discutidas.(AU)

A phylogenetic analysis of Brycon and Henochilus (Characiformes, Characidae, Bryconinae) based on the mitochondrial gene 16S rRNA

The genus Brycon, the largest subunit of the Bryconinae, has 42 valid species distributed from southern Mexico to the La Plata River in Argentina. Henochilus is a monotypic genus, comprising a single species (H. wheatlandii) found in the upper Rio Doce basin. In the present study, partial sequences of the mitochondrial gene 16S were obtained for fifteen species of Brycon and for Henochilus wheatlandii. The results showed that the genus Brycon is paraphyletic, since Henochilus is the sister-group of B. ferox and B. insignis. The most basal species analyzed were the trans-Andean species B. henni, B. petrosus, and B. chagrensis.