Emulsify 3 or 4 individual test strain colonies and transfer to a tube of saline. Compare turbidity to that in the 0. Adjust turbidity of inoculum to match that standard. Streak the swab over the entire surface of the agar plate by rotating the plate approximately 60o.
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Opening an E-test package 1. Equilibrate at room temperature. Ensure all the moisture has evaporated before opening. Inspect the package for holes or crack. Do not use if damaged. Do not cut between the blisters. Tip the strip out of the opening slightly and take them out with forceps.
If strips stick together, twist them apart with your fingers. Place the strips to be used into a dry clean Petri dish. Application of strips 1. Apply E -test strips with forceps. Ensure the MIC scale is facing upward i. Emulsify 3 or 4 individual test strain colonies and transfer to a tube of saline. Compare turbidity to that in the 0. Adjust turbidity of inoculum to match that standard or read with McFarland Std.
E test strips applying on the agar surface by using a forceps. Ensure that agar surface is dry before swabbing it. Allow the agar surface to dry for minutes. Do not apply it upside down. Use the templates to position strips on a mm plate or strips on a 90 mm plate. Quality Control Package labels for each antibiotic will carry performance and reproducibility data. The MIC is read from the the scale at the intersection of the zone with the strip as shown above figure Result and Interpretation: 1.
Read MIC at the point where ellipse intersects the scale. If a MIC value between two twofold dilutions is seen, always round up to the highest value. Read the MIC value at complete inhibition of all growth. If the intersect differs on either side of the strip, read the MIC as the greater value. Ignore any growth at the edge of the strip.
MIC readings of.
During the s, Hans Ericsson Professor of microbiology at the Karolinska Hospital and Karolinska Institute, Stockholm , the scientific founder of AB BIODISK, developed a method to standardize the disc diffusion method and to improve its reproducibility and reliability for clinical susceptibility predictions. The inhibition zone sizes from disc test results were compared to Minimum Inhibitory Concentration MIC values based on the reference agar dilution procedure. The correlation between zone sizes and MIC values was then assessed using regression analysis and regression lines were used for extrapolating zone interpretive limits that corresponded to the MIC breakpoint values that defined susceptible, intermediate and resistant categorical results. Etest applications include many groups of fastidious organisms, fungi yeast and mould and mycobacteria as well as detecting various mechanisms of resistance and MIC testing of key antibiotics with critical specimens e. Next to bacteria it can also be used to determine the MIC for certain fungi.
Resistance phenotype testing Principle of E-Test E test is a quantitative technique that is based on combination of concept of both dilution and diffusion principle for susceptibility testing. E test strip is placed on to an inoculated agar plate; there is an immediate release of antibiotics from the plastic carrier surface into the agar surface. After incubation, bacterial growth becomes visible, symmetrical inhibition ellipse along the strip is seen. Purpose of E-Test Determine the MIC of fastidious, slow-growing or nutritionally deficient micro-organisms, or for a specific type of patient or infection.
E-TEST ( Epsilometer test): Principle, purpose, procedure, results and interpretations
Opening an E-test package 1. Equilibrate at room temperature. Ensure all the moisture has evaporated before opening. Inspect the package for holes or crack. Do not use if damaged.