30-05-2012, 11:26 AM
MICROBIAL IDENTIFICATION AND ANTIBIOTIC SUSCEPTIBILITY TESTING BY USING THE VITEK® 2 SYSTEM
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INTRODUCTION
The VITEK 2 is an automated microbiology system utilizing growth-based technology. The system is available in three formats (VITEK 2 compact,VITEK 2, and VITEK 2 XL) that differ in increasing levels of capacity and automation. . All three systems accommodate the same colorimetric reagent cards that are incubated and interpreted automatically
VITEK 2 Compact
This format focuses on the industrial microbiology-testing environment while also having application for low to middle volume clinical laboratories. Features specifically developed for industrial microbiology include 21 CFR Part 11 compliance (for electronic records and signatures) and a colorimetric reagent card (BCL) used to identify the spore-forming Gram-positive bacilli (i.e., Bacillu and related genera). The other colorimetric reagent cards (GN, GP, YST) apply to all system formats for both industrial and clinical laboratories.
VITEK 2 and VITEK 2 XL
These formats are more focused on the clinical microbiology laboratory and provide increased levels of automation and capacity for higher volume laboratories. They also provide an option of automatic pipetting and dilution for antimicrobial susceptibility testing.
Reagent Cards
The reagent cards have 64 wells that can each contain an individual test substrate. Substrates measure various metabolic activities such as acidification,alkalinization, enzyme hydrolysis, and growth in the presence of inhibitory substances. An optically clear film present on both sides of the card allows for the appropriate level of oxygen transmission while maintaining a sealed vessel that prevents contact with the organism-substrate admixtures. Each card has a pre-inserted transfer tube used for inoculation (described below). Cards have bar codes that contain information on product type, lot number, expiration date, and a unique identifier that can be linked to the sample either before or after loading the card onto the system. Figure 2 shows the GN card.
VITEK 2 GN Colorimetric Identification Card.
There are currently four reagent cards available for the identification of different organism classes as follows:
1. GN - Gram-negative fermenting and non-fermenting bacilli
2. GP - Gram-positive cocci and non-spore-forming bacilli
3. YST - yeasts and yeast-like organisms
4. BCL - Gram-positive spore-forming bacilli
Product-specific details for each of the identification cards are shown below.
Culture Requirements
The on-line product information contains a culture requirements table that lists parameters for appropriate culture and inoculum preparation. These parameters include acceptable culture media, culture age, incubation conditions, and inoculum turbidity
Suspension Preparation
A sterile swab or applicator stick is used to transfer a sufficient number of colonies of a pure culture and to suspend the microorganism in 3.0 mL of sterile saline (aqueous 0.45% to 0.50% NaCl, pH 4.5 to 7.0) in a 12 x 75 mm clear plastic (polystyrene) test tube. The turbidity is adjusted accordingly (see Table 1) and measured using a turbidity meter called the DensiChekTM.
[attachment=23463]
INTRODUCTION
The VITEK 2 is an automated microbiology system utilizing growth-based technology. The system is available in three formats (VITEK 2 compact,VITEK 2, and VITEK 2 XL) that differ in increasing levels of capacity and automation. . All three systems accommodate the same colorimetric reagent cards that are incubated and interpreted automatically
VITEK 2 Compact
This format focuses on the industrial microbiology-testing environment while also having application for low to middle volume clinical laboratories. Features specifically developed for industrial microbiology include 21 CFR Part 11 compliance (for electronic records and signatures) and a colorimetric reagent card (BCL) used to identify the spore-forming Gram-positive bacilli (i.e., Bacillu and related genera). The other colorimetric reagent cards (GN, GP, YST) apply to all system formats for both industrial and clinical laboratories.
VITEK 2 and VITEK 2 XL
These formats are more focused on the clinical microbiology laboratory and provide increased levels of automation and capacity for higher volume laboratories. They also provide an option of automatic pipetting and dilution for antimicrobial susceptibility testing.
Reagent Cards
The reagent cards have 64 wells that can each contain an individual test substrate. Substrates measure various metabolic activities such as acidification,alkalinization, enzyme hydrolysis, and growth in the presence of inhibitory substances. An optically clear film present on both sides of the card allows for the appropriate level of oxygen transmission while maintaining a sealed vessel that prevents contact with the organism-substrate admixtures. Each card has a pre-inserted transfer tube used for inoculation (described below). Cards have bar codes that contain information on product type, lot number, expiration date, and a unique identifier that can be linked to the sample either before or after loading the card onto the system. Figure 2 shows the GN card.
VITEK 2 GN Colorimetric Identification Card.
There are currently four reagent cards available for the identification of different organism classes as follows:
1. GN - Gram-negative fermenting and non-fermenting bacilli
2. GP - Gram-positive cocci and non-spore-forming bacilli
3. YST - yeasts and yeast-like organisms
4. BCL - Gram-positive spore-forming bacilli
Product-specific details for each of the identification cards are shown below.
Culture Requirements
The on-line product information contains a culture requirements table that lists parameters for appropriate culture and inoculum preparation. These parameters include acceptable culture media, culture age, incubation conditions, and inoculum turbidity
Suspension Preparation
A sterile swab or applicator stick is used to transfer a sufficient number of colonies of a pure culture and to suspend the microorganism in 3.0 mL of sterile saline (aqueous 0.45% to 0.50% NaCl, pH 4.5 to 7.0) in a 12 x 75 mm clear plastic (polystyrene) test tube. The turbidity is adjusted accordingly (see Table 1) and measured using a turbidity meter called the DensiChekTM.