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Anandi Martin - One of the best experts on this subject based on the ideXlab platform.
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evaluation of the Resazurin assay for the detection of multidrug resistant mycobacterium tuberculosis in madagascar
International Journal of Tuberculosis and Lung Disease, 2007Co-Authors: N Rivoire, Anandi Martin, Francoise Portaels, P Ravololonandriana, T Rasolonavalona, H Ramarokoto, Rasolofo V RazanamparanyAbstract:SETTING: Multidrug-resistant (MDR) tuberculosis (TB) can jeopardise the success of national TB control programmes. Rapid, simple drug susceptibility tests applicable in developing countries would allow earlier treatment of patients with MDR infections. OBJECTIVE: To test the feasibility and performance of the Resazurin microtitre assay (REMA) as an indirect test for detecting isoniazid (INH) and rifampicin (RMP) resistance of Mycobacterium tuberculosis strains in Madagascar. DESIGN: Study comparing the sensitivity and specificity of the REMA plate test with the Lowenstein-Jensen proportion method for determining the resistance of M. tuberculosis strains to INH and RMP. RESULTS: The sensitivity and specificity of the Resazurin test were studied in 77 strains and were respectively 95% and 97.3% for the detection of INH resistance, and 95% and 100% for the detection of RMP resistance. The sensitivity and specificity for the identification of MDR strains were respectively 89% and 100%. CONCLUSION: The Resazurin test is sensitive and specific enough for the detection of INH- and RMP-resistant strains. It is also easy to use, rapid and inexpensive, making it suitable for developing countries. Its usefulness for national drug resistance surveys should be assessed.
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multicenter study of mtt and Resazurin assays for testing susceptibility to first line anti tuberculosis drugs
International Journal of Tuberculosis and Lung Disease, 2005Co-Authors: Anandi Martin, Ernesto Montoro, Dihadenys Lemus, Nora Morcillo, Mad Telles, Norberto Simboli, M Pontino, Tania Bibiana Porras, Clara Ines Leon, M VelascoAbstract:OBJECTIF : Une evaluation multicentrique a ete realisee dans le but d'etudier la performance de deux methodes rapides et peu couteuses, les tests MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) et Resazurin, pour la detection de la resistance de Mycobacterium tuberculosis aux medicaments antituberculeux de premiere intention : rifampicine (RMP), isoniazide (INH), ethambutol (EMB) et streptomycine (SM). METHODES : Trente souches codees de M. tuberculosis ont ete envoyees a sept laboratoires localises en Amerique Latine, representant six pays. Chaque laboratoire a realise de maniere aveugle les methodes colorimetriques, MTT et Resazurin pour les medicaments de premiere ligne, RMP, INH, EMB et SM ; les resultats de la concentration minimale inhibitrice ont ete compares a la methode des proportions sur milieu de Lowenstein-Jensen. RESULTATS : Apres avoir etabli la concentration critique pour chaque antibiotique, d'excellents resultats ont ete obtenus pour la RMP, l'INH et l'EMB, avec une specificite et une sensibilite comprises entre 96% et 99%. CONCLUSION: Les tests colorimetriques MTT et Resazurin sont des methodes alternatives tres prometteuses et accessibles aux pays a revenus moyens ou faibles qui devraient disposer de methodes rapides et peu couteuses pour realiser les tests de sensibilite de M. tuberculosis aux medicaments antituberculeux de premiere intention.
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comparative evaluation of the nitrate reduction assay the mtt test and the Resazurin microtitre assay for drug susceptibility testing of clinical isolates of mycobacterium tuberculosis
Journal of Antimicrobial Chemotherapy, 2005Co-Authors: Ernesto Montoro, Anandi Martin, Francoise Portaels, Dihadenys Lemus, Miguel Echemendia, Juan Carlos PalominoAbstract:OBJECTIVES: To evaluate the performance of three rapid low-cost methods for the detection of resistance to first-line drugs in Mycobacterium tuberculosis. METHODS: One hundred M. tuberculosis clinical isolates were tested by the nitrate reductase assay (NRA), the MTT test and the Resazurin microtitre assay (REMA), and the results compared with those obtained with the gold standard proportion method (PM) on Lowenstein Jensen medium. RESULTS: The results using the three methods showed a good sensitivity and specificity between 94% and 100% for the detection of rifampicin and isoniazid resistance. Specificity for ethambutol and streptomycin using MTT and Resazurin was low (58-89%). In contrast, NRA showed a good agreement for all first-line drugs tested. CONCLUSIONS: This study shows a high level of agreement of these three low-cost methods compared with the PM for rapid detection of rifampicin and isoniazid resistance. However, more standardization is needed for ethambutol and streptomycin using the MTT test and Resazurin microtitre assay. The nitrate reductase assay might represent an inexpensive procedure for rapid detection of resistance to first-line drugs in low-resource countries.
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rapid detection of ofloxacin resistance in mycobacterium tuberculosis by two low cost colorimetric methods Resazurin and nitrate reductase assays
Journal of Clinical Microbiology, 2005Co-Authors: Anandi Martin, Juan Carlos Palomino, Francoise PortaelsAbstract:We have evaluated the performance of two rapid, low-cost methods for the detection of ofloxacin (OFX) resistance with 95 Mycobacterium tuberculosis isolates from countries with high multidrug-resistant tuberculosis endemicity. Results obtained by nitrate reductase and Resazurin assays showed 100% agreement with those of the proportion method on 7H11 agar using 2 μg of OFX/ml. We confirmed the resistance of all isolates found to be resistant to OFX by the Mycobacterium Growth Indicator Tube system, and complete agreement among all methods was observed. Nitrate reductase and Resazurin assays are rapid, simple, low-cost methods and might become inexpensive alternative procedures for rapid detection of OFX resistance in low-resource countries.
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Resazurin microtiter assay plate testing of mycobacterium tuberculosis susceptibilities to second line drugs rapid simple and inexpensive method
Antimicrobial Agents and Chemotherapy, 2003Co-Authors: Anandi Martin, Mirtha Camacho, Francoise Portaels, Juan Carlos PalominoAbstract:The emergence of multidrug-resistant tuberculosis calls for new, rapid drug susceptibility tests. We have tested 150 Mycobacterium tuberculosis isolates against the second-line drugs ethionamide, kanamycin, capreomycin, ofloxacin, and para-aminosalicylic acid by the colorimetric Resazurin microtiter assay and the proportion method. By visual reading, MICs were obtained after 8 days. A very good correlation between results by the colorimetric Resazurin microtiter assay and the proportion method was obtained. The colorimetric Resazurin microtiter assay is inexpensive, rapid, and simple to perform, and implementation of the assay is feasible for low-resource countries.
Adyary Fallarero - One of the best experts on this subject based on the ideXlab platform.
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pros and cons of using Resazurin staining for quantification of viable staphylococcus aureus biofilms in a screening assay
Journal of Microbiological Methods, 2009Co-Authors: Malena Sandberg, Denise Schellmann, Gerda Brunhofer, Thomas Erker, Igor Busygin, Reko Leino, Pia Vuorela, Adyary FallareroAbstract:Abstract Staining of Staphylococcus aureus biofilms with 20 µM Resazurin during 20 min was shown to provide a good screening assay in 96-well micro titer plates. However, data quality was found to be dependent on the staining duration and biofilm concentration. Also, the inadequacy of using Resazurin calibration curves with planktonic cells to estimate S. aureus biofilm concentrations was demonstrated.
Frank Comhaire - One of the best experts on this subject based on the ideXlab platform.
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The correlates and alleged biochemical background of the Resazurin reduction test in semen
International Journal of Andrology, 2002Co-Authors: A. Zalata, N Lammertijn, Armand Christophe, Frank ComhaireAbstract:Reduction of the blue dye Resazurin to pink resorufin is used to estimate the concentration of metabolically active spermatozoa in semen samples. In order to quantify the reduction of Resazurin, a spectrophotometric method was developed measuring the change from blue to pink in the butanol extracted colour. The biochemical mechanisms involved in the reduction of Resazurin by motile spermatozoa and seminal plasma were investigated. Addition of NADH + H+ to sperm suspension or seminal plasma increased the reduction of Resazurin. The reduction reaction was inhibited by high concentrations of dicoumarol, a specific inhibitor of the diaphorase enzyme, in a dose-dependent manner. It is suggested that the sperm diaphorase enzyme transfers electrons from NADH + H+ to Resazurin, reducing it to resorufin. The degree of Resazurin reduction was strongly correlated with the concentration of motile spermatozoa recovered from the 90% Percoll fraction (r = 0.98, p
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the correlates and alleged biochemical background of the Resazurin reduction test in semen
International Journal of Andrology, 2002Co-Authors: A. Zalata, N Lammertijn, Armand Christophe, Frank ComhaireAbstract:Reduction of the blue dye Resazurin to pink resorufin is used to estimate the concentration of metabolically active spermatozoa in semen samples. In order to quantify the reduction of Resazurin, a spectrophotometric method was developed measuring the change from blue to pink in the butanol extracted colour. The biochemical mechanisms involved in the reduction of Resazurin by motile spermatozoa and seminal plasma were investigated. Addition of NADH + H+ to sperm suspension or seminal plasma increased the reduction of Resazurin. The reduction reaction was inhibited by high concentrations of dicoumarol, a specific inhibitor of the diaphorase enzyme, in a dose-dependent manner. It is suggested that the sperm diaphorase enzyme transfers electrons from NADH + H+ to Resazurin, reducing it to resorufin. The degree of Resazurin reduction was strongly correlated with the concentration of motile spermatozoa recovered from the 90% Percoll fraction (r = 0.98, p < 0.001). A positive correlation was also found between the reducing capacity of seminal plasma (n = 62) on the one hand, and sperm concentration (r = 0.72, p < 0.0001), progressive motility (r = 0.45, p < 0.01), normal morphology (r = 0.50, p < 0.01), and γ-glutamyltransferase (r = 0.36, p < 0.05) on the other hand. These findings, together with our previous observations that the reduction reaction is inhibited by reactive oxygen species and polymorphonuclear white blood cells, increase our understanding of the biochemical basis of the Resazurin test and may provide better insight into the interpretation of this test.
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andrology relationship between Resazurin reduction test reactive oxygen species generation and γ glutamyltransferase
Human Reproduction, 1995Co-Authors: Adel Zalata, Tarek Hafez, Ahmed Mahmoud, Frank ComhaireAbstract:: The production of reactive oxygen species (ROS) from spermatozoa has been measured by chemiluminescence in the two fractions of a Percoll gradient column (47 and 90%). Chemiluminescent signals were recorded in each fraction after addition of luminol and horse-radish peroxidase (basal state), and after stimulation with formyl-methionyl-leucyl-phenyl-alanine (FMLP) and phorbol ester (PMA). We found an inverse correlation between the reducing capacity of the semen as estimated by the Resazurin test, and the production of ROS by the spermatozoa, especially after stimulation with PMA (r = 0.51, P < 0.001). gamma-glutamyltransferase activity of seminal plasma was inversely correlated with ROS (r = -0.47, P < 0.01) and the Resazurin test result (r = -0.43, P < 0.001) suggesting a possible role of prostatic secretions in the protection of spermatozoa against oxygen radicals. The Resazurin test has a positive predictive value of 92.5% at a criterion value of colour scale 4 to discriminate between normal and excessive ROS production by spermatozoa, with sensitivity 79% and specificity 74%. In addition, at criterion value of colour scale 3, the Resazurin test could distinguish between samples with normal or low activity of gamma-glutamyltransferase, with sensitivity 57% and specificity 93%. It is concluded that the result of the Resazurin test can be influenced by the oxidative stress of spermatozoa and by prostatic function.
Eugenia Marti - One of the best experts on this subject based on the ideXlab platform.
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development of a smart tracer for the assessment of microbiological activity and sediment water interaction in natural waters the Resazurin resorufin system
Water Resources Research, 2008Co-Authors: Roy Haggerty, Alba Argerich, Eugenia MartiAbstract:Received 16 November 2007; revised 25 February 2008; accepted 14 March 2008; published 23 July 2008. [1] A ‘‘smart’’ tracer is a tracer that provides, directly or through measurement of its concentration or in combination with another compound, at least one ‘‘bit’’ more of information about the environment through which it travels than a conservative tracer. In this study we propose and present the chemical compound Resazurin as a smart tracer to assess the coupling between solute transport and microbiological activity in sediment-water interfaces in freshwaters. Resazurin is a weakly fluorescent redox-sensitive dye that undergoes an irreversible reduction to strongly fluorescent resorufin under mildly reducing conditions, most commonly in the presence of living microorganisms. To investigate the suitability of Resazurin as a smart tracer, we characterized the decay, sorption, reaction, and transport behavior of Resazurin and resorufin in various waters and sediments using laboratory experiments. Results show that Resazurin irreversibly and rapidly reacts to resorufin in colonized sediment with pseudo-first-order behavior and a rate coefficient of 1.41 h � 1 . This reaction is 3 orders of magnitude faster than that in stream water alone, indicating the tracer is sensitive to microbiological activity and associated sediment-water interactions. The compounds are affected by significant sorption, with an approximately linear isotherm and a Kd of 6.63 mL/g for resorufin in sediment with 2.19% organic carbon. The compounds are stable over weeks in natural water, except in the presence of strong light where significant photochemical decay may occur more rapidly.
Lynette B. Keur - One of the best experts on this subject based on the ideXlab platform.
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Role of Xanthine Oxidase in the Reduction of Resazurin by Raw Milk
Journal of Dairy Science, 2010Co-Authors: J.j.r. Campbell, Lynette B. KeurAbstract:The addition to raw milk of a variety of substrates for xanthine oxidase resulted in an almost immediate reduction of Resazurin. When no substrate was added, doubling the concentration of xanthine oxidase in raw milk by the addition of purified enzyme did not cause a significant increase in the rate of Resazurin reduction, confirming the conclusion that the unavailability of substrate limits the reducing activity of this enzyme. Milk from two cows which were very low in xanthine oxidase did show an increased reduction rate on the addition of the purified enzyme, but the final rate was still much too slow to have any bearing on the commercial grade of the milk. The pasteurization of milk destroyed the ability to reduce Resazurin but had little influence on the activity of xanthine oxidase. The addition to milk of folic acid, a very effective competitive inhibitor for xanthine oxidase, failed to slow the rate of Resazurin reduction signiflcantly. All of these factors point to the fact that xanthine oxidase does not play a significant role in the reduction of Resazurin by raw milk. © 1961, American Dairy Science Association. All rights reserved.
