IA Rev. Ferric chloride need not to be added since the medium already contains an iron salt. Organisms capable of utilizing citrate produce alkaline metabolites which change in the color of the indicator from green acidic to deep blue alkaline. Do not flame wire. These chemical reactions make up the More information. Inoculate BBL Enterotube II by first twisting wire, then withdrawing wire through all twelve compartments applying a turning motion Figure 2.
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The group to which an organism belongs must be determined by a combination of biochemical tests, not by a single property. Various schema based on selected biochemical tests have been advocated to simplify the identification of Enterobacteriaceae. It has prepared sterile multimedia tube for rapid differential identification of Gram-negative bacteria Enterobacteriaceae.
The self-contained, sterile, compartmented plastic tube contains twelve different conventional media plus a self-contained inoculating wire. The checked positive numbers are totaled, and the composite number is then located in the Interpretation Guide to identify the organisms.
Where two or more organisms are listed, the confirmatory tests required to further identify them are also given. Media Medium 1 Glucose : Glucose The medium is covered with wax to provide anaerobic conditions and to allow detection of gas formation.
Uninoculated: red. Medium 2 Lysine : Lysine The medium is covered with wax to provide anaerobic conditions. Uninoculated: yellow. Medium 3 Ornithine : Ornithine Uninoculated: Beige to light amber. Medium 5 Adonitol : Adonitol Medium 6 Lactose : Lactose Medium 7 Arabinose : Arabinose Medium 9 Voges-Proskauer : Glucose Uninoculated: colorless to light amber. Uninoculated: green. Medium 11 Urea : Urea Uninoculated: beige to light amber. Medium 12 Citrate : Sodium citrate 2. The wire is sterile and need not be flamed.
Inoculate by touching the wire to a well isolated colony from a Petri plate. The culture used should be at least 18 hours old and a pure culture of a Gram negative rod. Note: A visible amount of inoculum should be seen at the tip and the side of the wire. Avoid touching agar with wire. Inoculate BBL Enterotube II by first twisting wire, then withdrawing wire through all twelve compartments applying a turning motion Reinsert wire without sterilizing into BBL Enterotube II, using a turning motion through all 12 compartments, until the notch on the wire is aligned with the opening of the tube.
The tip of the wire should be seen in the citrate compartment. Break wire at notch by bending. The portion of the wire remaining in the tube maintains anaerobic conditions necessary for true fermentation of glucose, production of as and decarboxylation of lysine and ornithine.
Replace both caps. Allow for air circulation between incubated tubes. Interpret and record all reactions with exception of indole and Voges-Proskauer. All other tests must be read before the indole and Voges-Proskauer tests are performed as the reagents added for these tests may alter the remainder of the BBL Enterotube II reactions. Result Interpretation After 18 to 24 hours of incubation, interpret all reactions. With the exception of indole and VP, read the reactions in a sequential fashion by comparing the colors of the media in the tube after incubation with those given in the color scheme on the cover of the coding pad and with an uninoculated BBL Enterotube II which must be brought to room temperature first.
Indicate each positive test result by circling the number appearing below the appropriate compartment on the Results Pad. Finally, perform the indole and VP tests. If positive, circle the appropriate numbers on the prepared sheet.
Add circled numbers in the bracketed section and enter the sum in the space provided below the arrow. Make sure to use the right database [ 1 Oxidase negative nonfermenters, 2 Enterobacteriaceae — method without VP, and 3 Entero-bacteriaceae — method with VP]. The major advantage of the Enterotube is that all tests are done simultaneously by inoculation from a single isolated colony. It reduces the number of inoculations and the equipment needed to perform a series of biochemical tests for the identification.
Taxa other than those explained are not intended for use in this system. BBL Enterotube II biocodes cannot be used to establish phenotypic identity between isolates from the same or different specimens. Identification of Gram negative bacteria should be made with the consideration of additional characteristics such as source of specimen, history of the patient, colonial and microscopic morphology, serology and antimicrobial susceptibility patterns.
Identification of rare isolates should be repeated or additional testing performed to verify the identification of such organisms. Some strains of organisms may exhibit atypical biochemical reactions due to unusual nutritional requirements or mutations and may be difficult to identify. Some organisms may require longer than 24 hours incubation for proper identification.
References Titsworth, E. Efficiency of a multitest system Enterotube for rapid identification of Enterobacteriaceae.
ENTEROTUBE II INTERPRETATION GUIDE PDF
The Enterotube™ II – Procedure, Result Interpretation, Merits and Limitations