Insights into multiple use water enterobacteria from the Brazilian semi-arid: the first approach by pyrosequencing

Thousands of people living in semi-arid regions face problems of drought and loss of water quality. In addition, high incidence of acute diarrheal diseases related to water consumption has been responsible for a high number of deaths and high economic costs for human health. Many of the diseases can be caused by the presence of enterobacteria in reservoirs that serve for multiple purposes. This study aimed to confirm the presence of potentially harmful bacteria, which was highlighted in other articles, and to reveal non-identified genera by culture-dependent methods and pyrosequencing. Twenty-three genera of the Enterobacteriaceae family were detected, with emphasis on Escherichia genus and confirmation of the presence of species such as Salmonella enterica and Enterobacter cloacae. The abundance of heterotrophic prokaryotes and the physical and chemical data show an expected average for this type of environment due to the numbers historically presented in previous articles. The unprecedented detection of the presence of some potentially pathogenic species can alert and raise awareness of the populations that use stored water in the semi-arid regions. Consequently, as a result of the peculiar characteristics of reservoirs under this climate influence, there is a cosmopolitanism of enterobacteria that may be related to the alarming numbers of infections from Waterborne Diseases.

Evaluación del Agar Azul Bromotimol Lactosa introducido en BioCen con cepas de referencia / Assessment of Agar Blue Bromotimol Lactose introduced in BioCen using reference strans

Exponer los resultados obtenidos en las evaluaciones realizadas a los medios de cultivo Agar azul bromotimol lactosa producido en BioCen, Cuba, y el comercializado por la Merck, Alemania, destinado para la diferenciación de microorganismos especialmente las enterobacterias, por su capacidad de fermentar la lactosa. Se ensayaron un total de 13 cepas certificadas y una aislada de muestra de agua, pertenecientes al Departamento de Investigaciones de Medios de Cultivo (BioCen). Las cepas evaluadas en ambos productos mostraron similitud en cuanto a su respuesta y a las características morfológicas de las colonias. Los valores del índice relativo de crecimiento (IRC) para 10 cepas superaron el 90 por ciento, resultando el 71,5 por ciento del total, mientras que solo 4 cepas reflejaron valores inferiores, resultando el 28,5 por ciento del total. Todas las cepas sobrepasaron el valor recomendado (> 70 por ciento), además las características culturales desarrolladas respondían a las reportadas. Los resultados alcanzados en la determinación del IRC demuestran la buena calidad del medio producido en BioCen frente a cepas de referencia, tomando como criterio el hecho de que todos los microorganismos ensayados mostraron valores del IRC superiores al valor recomendado.

To show results obtained in evaluations performed in agar blue bromotimol lactose culture media produced in BioCen, Cuba, and that marketed by Merck, Germany, created for microorganism differentiation, specially the Enterobacter ones, due to its ability for lactose fermentation. We assayed a total of 13 certified strains and another isolated from water sample, from Research Department of Culture Media (BeioCen). Values or Growing Relative Index for 10 strains were above 90 percent, with 71,5 percent of total, while that only 4 strains shoed lower values to a 28,5 percent of total. All strains exceeded the recommended value (>70 percent). Strains evaluated in both products showed similarity as regard its response and to morphologic features of colonies.

In silico comparison of bacterial strains using mutual information.

Fast-sequencing throughput methods have increased the number of completely sequenced bacterial genomes to about 400 by December 2006, with the number increasing rapidly. These include several strains. In silico methods of comparative genomics are of use in categorizing and phylogenetically sorting these bacteria. Various word-based tools have been used for quantifying the similarities and differences between entire genomes. The simple di-nucleotide frequency comparison, codon specificity and k-mer repeat detection are among some of the well-known methods. In this paper, we show that the Mutual Information function, which is a measure of correlations and a concept from Information Theory, is very effective in determining the similarities and differences among genome sequences of various strains of bacteria such as the plant pathogen Xylella fastidiosa, marine Cyanobacteria Prochlorococcus marinus or animal and human pathogens such as species of Ehrlichia and Legionella. The short-range three-base periodicity, small sequence repeats and long-range correlations taken together constitute a genome signature that can be used as a technique for identifying new bacterial strains with the help of strains already catalogued in the database. There have been several applications of using the Mutual Information function as a measure of correlations in genomics but this is the first whole genome analysis done to detect strain similarities and differences.

The characteristics of extended-spectrum beta-lactamases in Korean isolates of Enterobacteriaceae

Extended-spectrum beta-lactamases (ESBLs) in gram-negative organisms have been implicated as the enzymes responsible for resistance to oxyimino-cephalosporins. The incidence of ESBL- producers in Korean isolates of Escherichia coli and Klebsiella pneumoniae were in the range of 4.8 7.5% and 22.5 22.8%, respectively. The ESBL-producing isolates revealed variable levels of resistance to cefotaxime, ceftazidime and aztreonam. They also showed the elevated MIC values of non-beta-lactam antibiotics. SHV-12 and SHV-2a were the enzymes most frequently found in K. pneumoniae strains, but TEM-52 was the most prevalent in E. coli isolates. About 15% of ESBL-producing isolates of Enterobacteriaceae produced CMY-1 enzyme, which conferred resistance to cephamycins such as cefoxitin as well as oxyimino-cephalosporins. Thus, the most common types of ESBLs in Korea are TEM-52, SHV-12, SHV-2a, and CMY-1.