Article

Novel quality assurance procedure for the Gram strain

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Abstract

The Gram staining procedure is one of the most basic and important tests performed in the clinical microbiology laboratory. Currently, the only control method for determining the validity of this test is by the use of known bacterial cultures. Consequently, a novel method using the KOH technique for confirming the Gram staining reaction is described. This chemical procedure has been found to be a simple, effective and accurate quality control method for the Gram stain.

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... Coloration à la fuchsine 10 % pendant l à 2 minutes, puis lavage à l'eau et séchage.Les bactéries Gram + positif apparaissent violettes ; les bactéries Gramnégatif sont roses.Une méthode de contrôle de la validité d'une coloration de Gram réalisée sur une bactérie à déterminer est d'utiliser des cultures témoins de bactéries connues. Une autre technique récente, simple et rapide, dite technique à la potasseKOHN et HENNEMAN, 1977) permet de vérifier le caractère Gram + ou Gram -d'une bactérie : A une goutte de potasse à 3 % déposée sur une lame de verre, on mélange une colonie de la bactérie à tester prélevée sur une culture de 24 heures en milieu gélosé. Si après 1 minute environ le mélange devient visqueux et filant, la bactérie est dite KOH+. ...
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