Método de la microgota: usado con agar cromogénico es un procedimiento útil para el monitoreo sanitario en acuicultura

Indexación: Web of Science, Scielo.The microdot method is a downscaling methodology of traditional tenfold serial dilution procedure used in microbiology. The microdot method uses 100 mu L for serial dilution and count colonies in a spot of 10 mu L. In this study we counted colonies directly in a chromogenic agar plate to determine, at the same time, the presence and cell concentration of target bacteria required for sanitary monitoring of Chilean export fishery products. Due to among importers countries the most concerning bacteria included in sanitary monitoring are Escherichia coli, Listeria monocytogenes and Staphylococcus aureus, we used the chromogenic agar; CHROMagar ECC, CHROMagar Listeria and Baird Parker agar, respectively. The results shows no differences between quantitative results obtained with microdot and traditional method during the quantification of a culture of Escherichia coli (1.5 L). The sensitivity and specificity of the microdot method in association with each chromogenic agar was demonstrated in vitro with reference strains. In addition, the usefulness in sanitary monitoring of aquaculture procedures was evaluated in Artemia salina tanks. This method did not detected sanitary problems in surface water. Although other colonies grown in the chromogenic agar plate, their morphological and chromogenic properties not correspond to Escherichia coli, Listeria monocytogenes and Staphylococcus aureus, being identified as Salmonella enterica subsp. enterica, Microbacterium sp., Bacillus sp. and Staphylococcus pasteuri by 16S rRNA gene sequence analysis. Hence, we propose the microdot chromogenic method as a low cost, specific and reliable procedure for sanitary monitoring of aquaculture procedures.El método de la microgota es una versión a menor escala del procedimiento tradicional de dilución en serie en base diez utilizados en microbiología. El método realiza diluciones en 100 µL y cuenta colonias crecidas en una gota de 10 µL. En este estudio se cuentan colonias directamente en placas cromogénicas para determinar densidad celular y presencia de bacterias requeridas en vigilancia sanitaria de productos pesqueros chilenos de exportación. Entre los requisitos de países importadores, la vigilancia sanitaria involucra frecuentemente a Escherichia coli, Listeria monocytogenes y Staphylococcus aureus, por lo que se utilizan los agares cromogénicos; CHROMagar ECC, CHROMagar Listeria y agar Baird Parker para su identificación. La comparación entre el método de microgota y el método tradicional no muestra diferencias al evaluar un cultivo de Escherichia coli (1,5 L). La sensibilidad y especificidad del método de microgota junto a cada agar cromogénico se demostró in vitro con cepas de referencia. Además, en estanques de Artemia salina se evaluó la utilidad de este método para el monitoreo sanitario. Este método no mostró problemas sanitarios en aguas superficiales, aunque otras colonias crecieron en la placa de agar cromogénico. Sus propiedades morfológicas y cromogénicas no corresponden a Escherichia coli, Listeria monocytogenes y Staphylococcus aureus, siendo identificadas según el análisis de la secuencia del gen 16S rRNA como Salmonella enterica subsp. enterica, Microbacterium sp., Bacillus sp. y Staphylococcus pasteuri. Por lo tanto, se propone el método de microgota cromogénico como un procedimiento de bajo costo, específico y fiable para el monitoreo sanitario en acuicultura.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2016000400009&lng=e

Culture of urine specimens by use of chromID CPS Elite medium can expedite Escherichia coli identification and reduce hands-on time in the clinical laboratory

Urine is one of the most common specimen types submitted to the clinical microbiology laboratory; the use of chromogenic agar is one method by which the laboratory might expedite culture results and reduce hands-on time and materials required for urine culture analysis. The objective of our study was to compare chromID CPS Elite (bioMérieux), a chromogenic medium, to conventional primary culture medium for evaluation of urine specimens. Remnant urine specimens (n = 200) were inoculated into conventional media and into chromID CPS Elite agar (chromID). The time to identification and consumables used were documented for both methods. Clinically significant pathogen(s) were recovered from 51 cultures using conventional media, with Escherichia coli being the most frequently recovered organism (n = 22). The rate of exact uropathogen agreement between conventional and chromogenic media was 82%, while overall categorical agreement was 83.5% The time interval between plating and final organism identification was decreased with chromID agar versus conventional media for E. coli (mean of 24.4 h versus 27.1 h, P < 0.001). Using chromID, clinically significant cultures required less hands-on time per culture (mean of 1 min and 2 s [1:02 min]) compared to conventional media (mean of 1:31 min). In addition, fewer consumables (2.4 versus 3.3 sticks and swabs) and rapid biochemical tests (1.0 versus 1.9) were necessary using chromID versus conventional media. Notably, antimicrobial susceptibility testing demonstrated good overall agreement (97.4%) between the chromID and conventional media for all antibiotics tested. chromID CPS Elite is accurate for uropathogen identification, reduces consumable usage, and may expedite the identification of E. coli in clinical specimens

Demonstration of earlier detection of Salmonella species from stool samples by using chromogenic media

Background: Salmonellosis is a worldwide public health issue and non-typhoid species are one of the most common causative agents of gastroenteritis in the western world.1 Typhoidal and Paratyphoidal salmonellae cause systemic syndromes characterised by sustained bacteraemia.2 Although the number of cases is under reported and therefore the incidence rates are underestimated,3 worldwide up to 1.3 billion non-typhoidal and an estimated 20 million typhoidal cases of Salmonella infection are reported annually.4,

A Selective and Sensitive Chromogenic and Fluorogenic Detection of a Sulfur Mustard Simulant

A simple and highly selective chromogenic and fluorogenic detection of sulfur mustard (SM) simulants is reported. Dithiol 1, in the presence and absence of a mustard simulant behaves differently toward a squaraine dye (SQ), and thus provides a visual and spectroscopic signal for mustard gas. The sensor responds to the SM simulant, but not to the O-analog of mustard stimulant or nerve agent mimics and other electrophilic agents. The visual and fluorescent detection with less than 50 mu M of SM simulant shows good sensitivity. The utility of the sensor was demonstrated by analysis of SM simulant on surfaces, in soil, and in the gas phase.Office of Naval Research N00014-09-1-1087Welch Foundation F-1151Department of Science and Technology, IndiaDefense Research and Development Organization, IndiaChemistr

Development of rapid, automated diagnostics for infectious disease: advances and challenges

The last 2 years has seen an exponential rise in the amount of research funding made available for the development of rapid diagnostic devices for infectious agents of medical importance. This review reports on several such projects. These highlight the development of fully automated devices for rapid diagnostics, ranging from fully automated real-time PCR-based detection methods to fully automated PCR- and array-based machines for the detection and typing of influenza. This review will also highlight the importance of refocusing work on classical immunoassay techniques, showing how biosensor-based immunoassays can greatly enhance existing assays and at a much reduced cost to molecular-based methods

Cultural methods of detection for microorganisms: recent advances and successes

Most microbiological methods require culture to allow organisms to recover or to selectively increase, and target organisms are identified by growth on specific agar media. Many cultural methods take several days to complete and even then the results require confirmation. Alternative techniques include the use of chromogenic and fluorogenic substances to identify bacteria as they are growing, selective capture using antibodies after short periods of growth, molecular techniques, and direct staining with or without flow cytometry for enumeration and identification. Future microbiologists may not use culture but depend on the use of specific probes and sophisticated detection systems

A micromethod for the determination of arginine

Micromethods for the determination of arginine based on the use of the Sakaguchi reagent have been described (14). This reagent gives a strong color with glycocyamine, arginine, and other monosubstituted guanidine derivatives. In a previous communication (5) a method for the determination of glycocyamine was described based on the Sakaguchi reaction and the quantitative separation of glycocyamine from arginine by selective adsorption of the arginine on permutit. In the method outlined below the separated arginine is eluted from the permutit and determined independently

A high-throughput screening method for determining the substrate scope of nitrilases

Nitrile compounds are intermediates in the synthesis of pharmaceuticals such as atorvastatin. We have developed a chromogenic reagent to screen for nitrilase activity as an alternative to Nessler's reagent. It produces a semi-quantifiable blue colour and hydrolysis of 38 nitrile substrates by 23 nitrilases as cell-free extracts has been shown

CD32-RNA Co-localizes with HIV-RNA in CD3+ Cells Found within Gut Tissues from Viremic and ART-Suppressed Individuals.

BackgroundIdentifying biomarkers for cells harboring replication-competent HIV is a major research priority. Recently, there have been mixed reports addressing the possibility that CD32-expressing T cells are enriched for HIV. There is growing evidence that CD32 expression increases with cellular activation that may be related to, but not necessarily specific for, infection with HIV. However, the relationship of CD32 expression to HIV-infection in subtypes of tissue-resident leukocytes is unclear.MethodsFirst, we used duplex chromogenic in situ hybridization to identify cells actively transcribing RNA for both CD32 and HIV on human gut tissues. Then we performed multiplexed immunofluorescence and in situ hybridization (mIFISH) on sections from the same tissues to determine the phenotype of individual cells co-expressing HIV-RNA and CD32-RNA.ResultsHIV-RNA+ cells were more abundant in tissues from viremic individuals than in those receiving suppressive anti-retroviral therapy (ART). However, staining by both methods indicated that a higher proportion of HIV-RNA+ cells co-expressed CD32-RNA in ART-suppressed individuals than in those with viremia. The majority of HIV-RNA+ cells were CD3+.ConclusionsOur data suggest that the transcription of CD32-RNA is correlated with HIV transcriptional activity in CD3+ cells found within human gut tissue. Whether or not up-regulation of CD32-RNA is a direct result of HIV transcription or more global T-cell activation remains unclear