Presentation on theme: "ADVANCE IDENTIFICATION SYSTEMS: VITEK 2 COMPACT Interamerican University of Puerto Rico Bayamón Campus Graduate Department Coral M. Rivera Johnathan J."— Presentation transcript:
ADVANCE IDENTIFICATION SYSTEMS: VITEK 2 COMPACT Interamerican University of Puerto Rico Bayamón Campus Graduate Department Coral M. Rivera Johnathan J. Rodríguez José Á. Pérez BIOL 6014 1
Objectives Principles of VITEK 2 compact. Components. VITEK 2 workflow. Reagent cards. Sample preparation. V ITEK 2 operation. Software operation. Cards Other features Conclusion References 2
Principles of VITEK 2 Compact The VITEK 2 compact system is an automated microbiology bacterial identification and antimicrobial susceptibility system. Uses advanced colorimetry technology to determine individual biochemical reactions contained in a variety of microbe identification cards. After inoculation with a standarized suspension of the unknown organism, each self- contained cards is incubated and read by the instrument’s internal optics. Comparison of results to known species specific reactions in the VITEK 2 database yields organism identifications. 3
Components 1. VITEK 2 Compact 2. Compact Workstation 3. Barcode Scanner 4. Shared Printer 5. UPS (Uninterruptible Power Supply) 6. Power Conditioner 7. Test Cassettes 8. DensiCHEK™ Plus 4
6 StepProcess Sample Preparation / Inoculum Standardization Bacterial suspensions prepared using a DensiCHEK™ Plus. Barcode reader inside the instrument reads barcode from the test kit. Linking Bar Code and Sample ID The test kit barcode is linked to the sample in the software. Not necessary to write sample ID on the test kit. Allows for alphanumeric entry up to 20 digits. Filling and Sealing the Test Kits Cassettes are placed into the Filler Station. Upon completion, user is prompted to place the cassette into the cassette Load/Unload Station where the cards are automatically sealed. Incubation and Analysis Sealed test kits are moved into the reader/incubator automatically. Test kits incubate and analyze automatically. Test kits are ejected automatically into the waste collection bin when complete. Test KitDispose of waste when cassette returns to the Load/Unload
Reagents Cards 7 The reagent cards have 64 wells contain an individual test substrate. Substrates measure 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. Each card has a pre-inserted transfer tube used for inoculation. 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. 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.
Reagents Cards 8 Reagent card – 64 wells with substrates of each test cards.
Sample preparation 9 Culture Requirements The product contains the culture requirements for appropriate culture and inoculum preparation. These parameters include acceptable culture media, culture age, incubation conditions, and inoculum turbidity. Suspension Preparation A sterile swab 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 (0.50% NaCl) in a clear plastic test tube. The turbidity is adjusted accordingly Table 1 and measured by DensiChekTM. Inoculation Identification cards are inoculated with microorganism suspensions by vacuum apparatus. The test suspension tube is placed into the “cassette”, while inserting the transfer tube into the suspension tube. Filled cassette is placed into a vacuum chamber station. introducing the organism suspension into micro-channels that fill all the test wells.
VITEK 2 compact 10 Table 1: Turbidity range for Card Inoculation
VITEK 2 Compact video 11 http://www.youtube.com/watch?v=1bVIcY30YU0
VITEK 2 operation 13 Card Sealing and Incubation Inoculated cards are passed by a mechanism, which cuts off the transfer tube and seals the card prior to loading into the carousel incubator. (accommodate up to 30 or up to 60 cards). All card types are incubated at 35.5 + 1.0ºC. Data are collected at 15-minute intervals during the entire incubation period. Optical System A transmittance optical system allows interpretation of test reactions using different wavelengths in the visible spectrum. A special algorithm is used to eliminate false readings due to small bubbles that may be present. Test Reactions Calculations are performed on raw data and compared to thresholds to determine reactions for each test. On the VITEK 2 Compact, test reaction results appear as “+”,” – “, [“(–)” or “(+)”. weak reactions that are too close to the test threshold].
Software operation 14 Database Development The databases are constructed with strain sets of well- characterized microorganisms, tested under various culture conditions. Strains are derived from a clinical, industrial and university culture collections. Analytical Techniques Test data from an unknown organism are compared to the respective database to determine a quantitative value for proximity to each of the database taxa. If a unique identification pattern is not recognized, a list of possible organisms is given, or the strain is determined to be outside the scope of the database. Identification Levels An unknown biopattern is compared to the database of reactions for each taxon, and a numerical probability calculation is performed. Various qualitative levels of identification are assigned based on the numerical probability calculation.
Software operation 16 Mixed Taxa Identifications This occurs when the biopattern is representative of a collective taxon and generates a genus-level, group-level, or slashline identification. Supplemental tests may be used to delineate representative species or subspecies of these collective taxa. Supplemental Testing In the case of low discrimination identifications, two or three choices are listed in the order of their probability calculations. The lab report contains recommended supplemental tests that allow for differentiation of choices in low discrimination identifications. Non-Reactive Biopattern When a biopattern is calculated for an unknown organism that is either completely negative or consists of both negative tests and tests with reactions that lie too close to the test thresholds, the identification result will be “Non-reactive biopattern.”
GN Cards 17 The GN card is used for the automated identification of 135 taxa of the most significant fermenting and non- fermenting Gram-negative bacilli. The GN card is based on established biochemical methods and newly developed substrates measuring carbon source utilization, enzymatic activities, and resistance ( ASM 1998, Chang et al. 2002, Coenye et al. 2001a, Coenye et al. 2001b, De Baere et al. 2001, Freney et al. 2000, Murray et al. 1999, Vandamme et al. 1999 ). There are 47 biochemical tests and one negative control well. Final identification results are available in approximately 10 hours or less.
GP Cards 23 The GP card is used for the automated identification of 115 taxa of the most significant non-spore-forming Gram-positive bacteria (primarily cocci). The GP identification card is based on established biochemical methods and newly developed substrates ( Atlas 1993, Barros et al. 2001, Collins and Lawson 2000, Collins et al. 2001, Freney et al. 2000, Holt et al. 1994, Murray et al. 1999, Poyart et al. 2002, Schlegel et al. 2000, Viera et al. 1998, Whiley et al. 1999 ). There are 43 biochemical tests measuring carbon source utilization, enzymatic activities and resistance. Final identification results are available in approximately eight hours or less.
YST Cards 28 The YST card is used for the automated identification of 49 taxa of the most significant yeasts and yeast-like organisms. The YST identification card is based on established biochemical methods and newly developed substrates ( Barnett et al. 2000, Larone 1995, Murray et al. 1999 ). There are 46 biochemical tests measuring carbon source utilization, enzymatic activities and resistance. Final identification results are available in approximately 18 hours.
BCL Cards 32 The BCL card is used for the automated identification of 38 taxa of the most significant aerobic endospore- forming species of the family Bacillaceae. The BCL identification card is based on established biochemical methods and newly developed substrates ( Atlas 1993, Logan et al. 2002, Logan and Turnbull 2003 ). There are 46 biochemical tests measuring carbon source utilization, enzymatic activities, inhibition, and resistance. Final identification results are available in approximately 14 hours.
Other features 37 Identification NH ID Card, Neisseria, Haemophilus and other fastidious Gram negative bacteria identification. ANC ID Card, Anaerobic bacteria and coryneform bacteria identification. Antibiotic Susceptibility Testing (AST) Gram positive antimicrobial susceptibility testing (AST) cards. Gram negative antimicrobial susceptibility testing (AST) cards. Yeast antimicrobial susceptibility testing (AST) card.
Conclusion 38 The VITEK 2 is an automated microbial identification system that provides highly accurate and reproducible results as shown in multiple independent studies. With its colorimetric reagent cards, and associated hardware and software advances, the VITEK 2 offers a state-of-the-art technology platform for phenotypic identification methods.
References 39 American Society for Microbiology. 98th General Meeting Workshop Program. Practical Approach to the Identification of the Medically Important Glucose Non-Fermenting Gram-Negative Bacilli. American Society for Microbiology, Washington, D.C. 1998. Atlas RA. Handbook of Microbiological Media. CRC Press, Ann Arbor. 1993. Barnett JA, Payne RW, Yarrow D, editors. Yeasts: Characteristics and Identification, 3rd ed. Cambridge University Press, New York. 2000. Barros RR, Carvalho GS, Peralta JM, Facklam RR, Teixeira LM. Phenotypic and Genotypic Characterization of Pediococcus Strains Isolated from Human Clinical Sources. J. Clin. Microbiol. 2001;39:1241-1246.
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References 42 Logan, N. A., Turnbull, P. C. B. 2003. Bacillus and recently derived genera. In Manual of Clinical Microbiology, 8 th ed., pp. 445-460. Edited by P. R. Murray, E. J. Baron, M. A. Pfaller, J. H. Jorgensen & R. H. Yolken. American Society for Microbiology, Washington, DC. Poyart C, Quesne G, Trieu-Cuot P. Taxonomic dissection of the Streptococcus bovis group by analysis of manganese-dependent superoxide dismutase gene (sodA) sequences: reclassification of Streptococcus infantarius subsp. coli as Streptococcus lutetiensis sp.nov. and of Streptococcus bovis biotype II.2 as Streptococcus pasteurianus sp nov. Int. J. Syst. Evol. Microbiol. 2002;52:1247- 1255. Schlegel L, Grimont F, Collins MD, Regnault B, Grimont PAD, Bouvet A. Streptococcus infantarius sp. nov., Streptococcus infantarius subsp infantarius subsp. nov. and Streptococcus infantarius subsp coli subsp. nov., isolated from humans and food. Int. J. Syst. Evol. Microbiol. 2000;50:1425-1434. Vandamme P, Goris J, Coenye T, Hoste B, Janssens D, Kersters K, DeVos P, Falsen E. Assignment of Centers for Disease Control group IVc-2 to the genus Ralstonia as Ralstonia paucula sp.nov. Int. J. Syst. Bacteriol. 1999;49:663-669.