Biofilm produced by Enterococcus faecalis isolated from root canals was detected by growing it on microplates and using 10% crystal violet stain, elution with alcohol and three procedures: no fixation, heat fixation and 10% formaldehyde fixation. The biofilm was evaluated using a Versamax Microplate Reader (USA). Twenty sterile root portions were incubated in TS broth with E. faecalis (108) for 48 hours, 4, 7, 14 and 30 days, after which they were processed and observed by scanning electron microscopy (SEM). Significantly more biofilm was found on the microplates for formaldehyde fixation than for heat fixation or no fixation (ANOVA p<0.0001). SEM showed E. faecalis growth at all times and biofilm development as from 14 days’ incubation. Fixation with 10% formaldehyde was the most appropriate technique for detecting E. faecalis biofilm development on microplates. SEM confirmed biofilm formation after 14 days incubation.

Se realizo la deteccion de biofilm de Enterococcus faecalis aislados de conductos radiculares, desarro llandolos en microcubetas realizando tincion con Cristal Violeta 10 %, elucion con alcohol y tres procedimientos: sin fijar, fijacion con calor y fija cion con formaldehido 10%. Se evaluo el biofilm formado realizando la lectura con lector de microplaca Versamax-Microplate-Reader (USA). Se incubaron 20 porciones radiculares esteriles en el medio TS caldo con E. faecalis (108) durante 48 hs, 4, 7, 14 y 30 dias. Transcurrido cada tiempo experi mental se procesaron y observaron al microscopio electronico de barrido (MEB). Se evidencio significativamente mayor formacion de biofilm en microplacas cuando se realizo fijacion con formaldehido, que al fijar con calor y sin fijar (ANOVA p<0,0001). Al MEB se observo crecimiento del E. faecalis en todos los tiempos y desarrollo de biofilm a partir de 14 dias de incubacion. La fijacion con formaldehido 10% fue la tecnica mas apropiada para detectar biofilm de E. faecalis desarrollado en microplacas. Mediante el MEB se confirmo la formacion de biofilm despues de 14 dias de incubacion.

Vibrio cholerae tem sido isolado esporadicamente nos rios da Província de Tucumán, Argentina, desde outubro de 1991. O objetivo deste estudo foi localizar os reservatórios nestes rios, identificar a presença de Vibrio cholerae O1 (em estado cultivável e não cultivável) e relacionar a presença desta bactéria com as variações físico-químicos da água. Foram coletadas dezoito amostras de água do rio Salí (nas localidades de Canal Norte e Banda) e do rio Lules, entre 2003 e 2005. Estas foram submetidas a análises físico-químicos como determinação de pH, temperatura, condutibilidade elétrica e oxigênio dissolvido. A presença de Vibrio cholerae foi verificada por métodos de cultivo convencional e por imunofluorescência direta (DFA-VNC). Todos os microrganismos isolados foram não O1 e não O139 (Lules 26%, Canal Norte 33% e Banda 41%). A maioria foi encontrada na primavera e verão, indicando uma relação com a temperatura e pH. Das 54 amostras analisadas por DFA-VNC, 38 Vibrio cholerae não cultivável, foram detectadas em todas as épocas do ano. As amostras positivas foram confirmadas por PCR para o antígeno somático O1 e para os genes de virulência ctxA e tcpA. Coeficiente de correlação de Pearson revelou que não há relação entre os resultados obtidos por imunofluorescência e a variação dos parâmetros físico-químicos.

Vibrio cholerae has been sporadically isolated from rivers in Tucumán, Argentina, since the outbreak in 1991. The aim of this study was to determine the environmental reservoir of the bacterium in these rivers, assessing the presence of Vibrio cholerae non-O1 and O1 (the latter both in its viable culturable and non culturable state) and its relationship to environmental physicochemical variables. 18 water samplings were collected in the Salí River (in Canal Norte and Banda) and the Lules River between 2003 and 2005. Physical-chemical measurements (pH, water temperature, electrical conductivity and dissolved oxygen) were examined. Vibrio cholerae was investigated with conventional culture methods and with Direct Immunofluorescence (DFA-VNC) in order to detect viable non culturable organisms. All isolated microorganisms corresponded to Vibrio cholerae non-O1 and non-O139 (Lules 26%, Canal Norte 33% and Banda 41%). The majority was found during spring and summer and correlated with temperature and pH. Non culturable Vibrio cholerae O1 was detected year round in 38 of the 54 water samples analyzed. Application of the Pearson correlation coefficient revealed that there was no relationship between positive immunofluorescence results and environmental physicochemical parameters. Genes coding for somatic antigen O1 were confirmed in all DFA-VNC-positive samples, whereas the virulence-associated ctxA and tcpA genes were confirmed in 24 samples.

A stable microbial system in the respiratory tract acts as an important defense mechanism against pathogenic microorganisms. Perturbations in this system may allow pathogens to establish. In an ecological environment such as the respiratory tract, there are many diverse factors that play a role in the establishment of the indigenous flora. In the present work we studied the normal microbial flora of different areas of the respiratory tract of mice and their evolution from the time the mice were born. Our interest was to know which were the dominant groups of microorganisms in each area, which were the first capable of colonizing and which dominated over time to be used as probiotic microorganisms. Our results show that Gram negative facultatively anaerobic bacilli and strict anaerobic microorganisms were the last ones to appear in the bronchia, while aerobic and Gram positive cocci were present in all the areas of the respiratory tract. The number of facultative aerobes and strict anaerobes were similar in the nasal passage, pharynx instilled and trachea, but lower in bronchia. The dominant species were Streptococcus viridans and Staphylococcus saprophyticcus, followed by S. epidermidis, Lactobacilli and S. cohnii I which were present on every studied days but at different proportions. This paper is the first part of a research topic investigating the protective effect of the indigenous flora against pathogens using the mice as an experimental model.