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The Xpert® MRSA/SA Skin and Soft Tissue Infection test (Xpert MRSA/SA SSTI test) performed on the GeneXpert® Instrument Systems is a qualitative in vitro diagnostic test intended for the detection of Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) from skin and soft tissue infection swabs. The test utilizes automated real-time polymerase chain reaction (PCR) to detect MRSA/SA DNA. The Xpert MRSA/SA SSTI test is indicated for use in conjunction with other laboratory tests, such as microbiology culture, and clinical data available to the clinician as an aid in the detection of MRSA/SA from skin and soft tissue infections. The Xpert MRSA/SA SSTI test is not intended to monitor treatment for MRSA/SA infections. Concomitant cultures for SA and MRSA are necessary to recover organisms for susceptibility testing or epidemiological typing. In a mixed culture containing MRSA/SA and other organisms (e.g., Gram-negative bacilli, yeast), results can be false negative or variable depending on the concentration of MRSA/SA present, particularly if the concentration of MRSA/SA is close to the limit of detection (LoD) of the test.

The Xpert MRSA/SA SSTI (Xpert MRSA/SA Skin and Soft Tissue Infection) test is an automated in vitro diagnostic DNA test for the qualitative, simultaneous detection of Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) directly from skin and soft tissue specimen swabs. The specimen is collected on a double swab, one of which is placed in a tube containing elution reagent. Following brief vortexing, the eluted material is transferred to a different, uniquely labeled sample chamber of a disposable fluidic cartridge (the Xpert MRSA/SA SSTI cartridge). The test is performed on the GeneXpert® Instrument Systems (comprised of the GeneXpert® Dx System, GeneXpert® System with Touchscreen, and GeneXpert® Infinity System). In the GeneXpert® Instrument Systems, sample preparation, amplification, and real-time detection are all fully automated and completely integrated. The platform requires the use of singleuse disposable cartridges that hold the PCR reagents and host the PCR process. Because the cartridges are self-contained, cross-contamination between samples is minimized. The user initiates a test from the system user interface of the GeneXpert® Instrument Systems platform and places the cartridge with sample into a GeneXpert® instrument system which performs hands-off real-time, multiplex polymerase chain reaction (PCR) for detection of SA and MRSA DNA. Depending upon the specific instrument, a GeneXpert® instrument system may contain 1–80 modules, each which are randomly accessible and capable of performing separate sample preparation and real-time PCR tests. Each module contains a syringe drive for dispensing fluids (i.e., the syringe drive activates the plunger that works in concert with the rotary valve in the cartridge to move fluids between chambers), an ultrasonic horn for lysing cells or spores, and a proprietary ICORE® thermocycler for performing real-time PCR and detection. The Xpert MRSA/SA SSTI test kit includes reagents for the simultaneous detection of the target organisms, SA and MRSA. The primers and probes in the Xpert MRSA/SA SSTI test detect nucleic acid sequences of the staphylococcal protein A (spa), the gene for methicillin/oxacillin resistance (mecA), and staphylococcal cassette chromosome (SCCmec) inserted in the SA chromosomal attB site. The test includes a sample processing control (SPC) to control for adequate processing of the target bacteria and to monitor the presence of inhibitor(s) in the PCR assay. The SPC also ensures that the PCR conditions (temperature and time) are appropriate for the amplification reaction and that the PCR reagents are functional. The Probe Check Control (PCC) verifies reagent rehydration, PCR tube filling in the cartridge, probe integrity, and dye stability. The Xpert MRSA/SA SSTI test performed on the GeneXpert® Instrument Systems provides results in approximately 62 minutes.

The Xpert® SA Nasal Complete test performed on the GeneXpert® Instrument Systems is a qualitative in vitro diagnostic test designed for detection of Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) from nasal swabs in patients at risk for nasal colonization. The test utilizes automated real-time polymerase chain reaction (PCR) to detect MRSA/SA DNA. The Xpert SA Nasal Complete test is intended to aid in the prevention and control of MRSA/SA infections in healthcare settings. The Xpert SA Nasal Complete test is not intended to diagnose, guide or monitor treatment for MRSA/SA infections, or provide results of susceptibility to methicillin. A negative result does not preclude MRSA/SA nasal colonization. Concomitant cultures are necessary to recover organisms for epidemiological typing or for further susceptibility testing.

The Xpert SA Nasal Complete test is an automated in vitro diagnostic DNA test for the qualitative, simultaneous detection of Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) directly from nasal swabs. The specimen is collected on a double swab, one of which is placed in a tube containing elution reagent. Following brief vortexing, the eluted material is transferred to different, uniquely-labeled chamber of the disposable fluidic cartridge (the Xpert SA Nasal Complete cartridge). The user initiates a test from the user interface of the GeneXpert® Instrument Systems and places the cartridge with sample into the GeneXpert® Instrument System platform, which performs hands-off real-time, multiplex polymerase chain reaction (PCR) for detection of S. aureus (including MRSA) DNA. In the GeneXpert® Instrument Systems (comprised of the GeneXpert® Dx Systems, GeneXpert® System with Touchscreen, and GeneXpert® Infinity Systems), sample preparation, amplification, and real-time detection are all fully-automated and completely integrated. The platform requires the use of single-use disposable cartridges that hold the PCR reagents and host the PCR process. Because the cartridges are self-contained, cross-contamination between samples is minimized. Depending on the specific instrument, the GeneXpert® Instrument Systems may contain 1–80 modules, each of which are randomly accessible and capable of performing separate sample preparation and real-time PCR tests. Each module contains a syringe drive for dispensing fluids (i.e., the syringe drive activates the plunger that works in concert with the rotary valve in the cartridge to move fluids between chambers), an ultrasonic horn for lysing cells or spores, and a proprietary I-CORE thermocycler for performing real-time PCR and detection. The Xpert SA Nasal Complete test kit includes reagents for the simultaneous detection of SA and MRSA targets. The primers and probes provided in the Xpert SA Nasal Complete test kit detects nucleic acid sequences of the staphylococcal protein A (spa), the gene for methicillin/oxacillin resistance (mecA), and staphylococcal cassette chromosome (SCCmec) inserted in the SA chromosomal attB site. The Xpert SA Nasal Complete cartridge includes a sample processing control (SPC) to control for adequate processing of the target bacteria and to monitor the presence of inhibitor(s) in the PCR assay. The Probe Check Control (PCC) verifies reagent rehydration, PCR tube filling in the cartridge, probe integrity, and dve stability. The Xpert SA Nasal Complete test performed on the GeneXpert® Instrument Systems provides results in approximately 65 minutes. Each instrument in the GeneXpert® Instrument family is equipped with a Windows OS-based personal computer that is preloaded with software applications for running the tests and viewing the results, as described in Table 1.

The ARIES® MRSA Assay is an integrated, real-time, polymerase chain reaction (PCR) based qualitative in vitro diagnostic test for the direct detection of methicillinresistant Staphylococcus aureus (MRSA) DNA from nasal swabs in patients at risk for nasal colonization. The ARIES® MRSA Assay is intended to aid in the prevention and control of MRSA infections in healthcare settings. The assay is not intended to guide, diagnose, or monitor treatment for MRSA infections. It is not intended to provide results of susceptibility to oxacillin/methicillin. A negative result does not preclude MRSA nasal colonization. Concomitant cultures are necessary to recover organisms for epidemiological typing or for further susceptibility testing. The ARIES® MRSA Assay is indicated for use with ARIES® Systems.

The ARIES® MRSA Assay is a polymerase chain reaction (PCR)-based qualitative in vitro diagnostic test system which consists of the ARIES® System or the ARIES® M1 System with their included ARIES® Software, a sample processing tube, an assay-specific cassette, and an assay-specific protocol file. The ARIES® MRSA Assay cassette is a disposable, single-use cassette containing nucleic acid purification reagents, internal sample process control (SPC), and an assay-specific master mix capable of performing the designated assay on one sample. The ARIES® MRSA Assay cassette directly detects methicillin-resistant Staphylococcus aureus (MRSA) from nasal swabs in patients at risk of nasal colonization. Specifically, the ARIES® MRSA Assay cassette detects the methicillin resistance genes (mecA and mecC), Staphylococcus aureus orfX gene, the SCCmec junction region, and a DNA Sample Processing Control. Nasal swab specimens are collected using the Liquid Amies Elution Swab (ESwab™) Collection and Transport System, or equivalent. A portion of the sample is transferred to the provided 2 mL ARIES MRSA Sample Processing Tube and vortexed. The processed sample is then transferred to the ARIES® MRSA Assay cassette. The specimen is lysed and nucleic acid is extracted using an ARIES® instrument. An extractable sample processing control (SPC) target present in the ARIES® MRSA Assay cassette is processed with the specimen. The SPC controls for recovery of extracted nucleic acid, for inhibitory substances and for PCR reagent and instrument integrity. The Ct value of the SPC is designed to verify nucleic acid extraction, to identify PCR inhibition, if any, and verify proper function of the extraction system and real-time instrument. The extracted nucleic acid and SPC are transferred via magnetic beads through the cassette to the ARIES® MRSA Assay lyophilized PCR reagents in the PCR tube that contain primer pairs and probes specific to mecA/mecC, orfX, SCCmec and the SPC sequence. Each probe is labeled with a distinct fluorophore and detected in a distinct channel of an ARIES® System. PCR amplification is performed and assay fluorescence is monitored. Hybridization of a fluorescently labeled probe to the amplified target results in the release of quenching and generation of fluorescence signal that is indicative of PCR generated amplicon. Following amplification, the reaction is heated to separate the fluorescentlabeled probe from the amplified target, a process that results in a decrease in the fluorescence signal. The reaction fluorescence is measured during this process and the temperature at which the change in fluorescence is the maximum is the Tm of the amplicon. The instrument fluorescence output is analyzed and test results are determined using the ARIES® System software and the ARIES® MRSA Assay protocol and run files. ARIES® MRSA Assay results may be reported from the ARIES® Software or from the optional SYNCT® Software.

The Cepheid® Xpert® MRSA/SA Blood Culture test, performed on the GeneXpert® Instrument Systems, is a qualitative in vitro diagnostic test intended for the detection of Staphylococcus aureus (SA) and methicillin-resistant Staphylococus aureus (MRSA) DNA directly from positive blood cultures. The assay utilizes automated real-time polymerase chain reaction (PCR) for the amplification of MRSA/SA specific DNA targets and fluorogenic target-specific hybridization probes for the real-time detection of the amplified DNA. The assay is performed directly on positive blood culture samples from BD BACTEC™ Plus Aerobic/F, BacT/ALERT® SA (Standard Aerobic) or VersaTREK REDOX 1® (aerobic) blood culture bottles that are determined by Gram Stain as Gram Positive Cocci in Clusters (GPCC) or as Gram Positive Cocci in singles (GPC). The Xpert MRSA/SA Blood Culture test is indicated for use in conjunction with other laboratory tests, such as culture, and clinical data available to the clinician as an aid in the detection of MRSA/SA from positive blood culturing of positive blood cultures is necessary to recover organisms for susceptibility testing or for epidemiological typing. The Cepheid Xpert MRSA/SA Blood Culture test is not intended to monitor treatment for MRSA/SA infections.

The Cepheid Xpert® MRSA/SA Blood Culture test is a rapid, automated DNA test for the simultaneous qualitative detection of MRSA and SA DNA directly from blood culture bottle samples that are detected as positive for microbial growth and shown to contain Gram Positive Cocci by Gram stain. The primers and probes in the Xpert MRSA/SA Blood Culture test detect nucleic acid sequences of the staphylococcal protein A (spa), the gene for methicillin/oxacillin resistance (mecA), and staphylococcal cassette chromosome (SCCmec) inserted in the SA chromosomal attB site. The test includes a Sample Processing Control (SPC) to control for adequate processing of the target bacteria and to monitor the presence of inhibitor(s) in the PCR assay. The Probe Check Control (PCC) verifies reagent rehydration, PCR tube filling in the cartridge, probe integrity, and dye stability. The sample for testing with the Xpert MRSA/SA Blood Culture test consists of an aliguot taken from a positive blood culture bottle. Using one of the disposable fixed 50 µL volume transfer pipettes provided with the test kit, an aliquot of the positive blood culture is transferred into a single-use tube of Elution Reagent, also provided with the kit. The Elution Reagent is briefly vortexed and the entire content is transferred to the sample chamber of the disposable fluidic cartridge (the Xpert MRSA/SA Blood Culture cartridge), after which the cartridge is ready to place on the instrument. The assay is performed on the Cepheid GeneXpert Systems, which automate and integrate sample purification, nucleic acid amplification and detection of the target sequences in simple or complex samples using real-time PCR. The systems consist of an instrument, personal computer, and preloaded software for running the tests and viewing the results. The GeneXpert Instrument Systems require the use of single-use disposable cartridges that hold the PCR reagents and host the PCR process. Because the cartridges are self-contained, cross-contamination between samples is minimized. In this platform, additional sample preparation, amplification, and real-time detection are all fullyautomated and completely integrated. The Xpert MRSA/SA Blood Culture test performed on the GeneXpert Instrument Systems provides results in approximately 60 minutes. The GeneXpert Instrument Systems, comprised of the GeneXpert Dx Systems and the GeneXpert Infinity Systems, have 1 to 80 randomly accessible modules, depending upon the instrument, that are each capable of performing separate sample preparation and realtime PCR tests. Each module contains a syringe drive for dispensing fluids (i.e., the syringe drive activates the plunger that works in concert with the rotary valve in the cartridge to move fluids between chambers), an ultrasonic horn for lysing cells or spores, and a proprietary I-CORE® thermocycler for performing real-time PCR and detection.

The Xpert® MRSA NxG Assay, performed on the GeneXpert® Instrument Systems, is a qualitative in vitro diagnostic test intended for the detection of methicillin-resistant Staphylococcus aureus (MRSA) DNA directly from nasal swabs in patients at risk for nasal colonization. The test utilizes automated real-time polymerase chain reaction (PCR) for the amplification of MRSA-specific DNA targets and fluorogenic target-specific hybridization probes for the real-time detection of the amplified DNA. The Xpert MRSA NxG Assay is intended to aid in the prevention and control of MRSA infections in healthcare settings. The Xpert MRSA NxG Assay is not intended to diagnose, guide, or monitor treatment for MRSA infections, or provide results of susceptibility to methicillin. A negative result does not preclude MRSA nasal colonization. Concomitant cultures are necessary to recover organisms for epidemiological typing or for further susceptibility testing.

The Xpert MRSA NxG Assay is an automated real-time polymerase chain reaction (PCR) in vitro diagnostic test for qualitative detection of methicillin-resistant Staphylococcus aureus (MRSA) directly from nasal swab specimens of patients at risk for colonization with MRSA in a healthcare setting. The Xpert MRSA NxG Assay is performed on the Cepheid GeneXpert® Instrument Systems (GeneXpert Dx, GeneXpert Infinity-48, GeneXpert Infinity-48s, and GeneXpert Infinity-80 systems). The GeneXpert Instrument System platform automates sample preparation, amplification and real-time detection. The GeneXpert Instrument Systems require the use of single-use, disposable cartridges (the Xpert MRSA NxG cartridges) that hold the PCR reagents and host the PCR process. Because the cartridges are self-contained and specimens never come into contact with working parts of the instrument modules, cross-contamination between samples is minimized. The Xpert MRSA NxG Assay includes reagents for the detection of target MRSA DNA. The primers and probes in the Xpert MRSA NxG Assay detect proprietary sequences for the gene for methicillin/oxacillin resistance (mecA and mecC), and staphylococcal cassette chromosome mec (SCCmec), which is inserted into the SA chromosomal attB site. A Sample Processing Control (SPC) and a Probe Check Control (PCC) are internal controls utilized by the GeneXpert Instrument System platform. The SPC is present to control for adequate processing of the target bacteria and to monitor for the presence of inhibitor(s) in the PCR assay to avoid false-negative results. The Probe Check Control verifies reagent rehydration, real-time PCR tube filling in the cartridge, probe integrity, and dye stability. The single-use, multi-chambered fluidic cartridges are designed to complete sample preparation and real-time PCR for the detection of genomic DNA from methicillinresistant Staphylococcus aureus (MRSA) in 70 minutes or less. The GeneXpert Instrument Systems, comprised of the GeneXpert Dx Systems and the GeneXpert Infinity Systems, have 1 to 80 randomly accessible modules, depending upon the instrument, that are each capable of performing separate sample preparation and real-time PCR and RT-PCR tests. Each module contains a syringe drive for dispensing fluids (i.e., the syringe drive activates the plunger that works in concert with the rotary valve in the cartridge to move fluids between chambers), an ultrasonic horn for lysing cells or spores, and a proprietary I-CORE® thermocycler for performing real-time PCR and RT-PCR and detection. Nasal swab specimens are collected using the Cepheid Sample Collection Device and are transported to the laboratory or designated GeneXpert testing area. The nasal swab specimen is placed in a tube containing 2 mL of Elution Reagent. Following a brief vortexing of the sample, the entire contents of the Elution Reagent tube are transferred to the sample chamber of the Xpert MRSA NxG cartridge using a transfer pipette. For nasal swab specimens that are collected using Copan Liquid Amies Elution Swab (ESwab) collection and transport system, 300 uL of liquid sample is transferred to a tube containing 2 mL of Elution Reagent. Following a brief vortexing of the sample, the entire contents of the Elution Reagent tube are transferred to the sample chamber of the Xpert MRSA NxG cartridge using a transfer pipette. The user initiates a test from the system user interface and places the cartridge into the GeneXpert instrument platform, which performs hands-off real-time, multiplex PCR for detection of DNA. The results are automatically generated at the end of the process in a report that can be viewed and printed.

The cobas® MRSA/SA Test on the cobas® 4800 system, is a qualitative in vitro diagnostic real-time PCR assay, for the direct detection of methicillin-resistant Staphylococus aureus (MRSA) and S.aureus (SA) DNA from nasal swabs to aid in the prevention and control of MRSA and SA infections in healthcare settings. The cobas® MRSA/SA Test is not intended to diagnose, guide or monitor treatment for MRSA or SA infections, or provide results of susceptibility to methicillin. A negative result does not preclude MRSA/SA nasal colonization. Concomitant cultures are necessary to recover organisms for epidemiology typing or for further susceptibility testing.

The Roche Molecular Systems (RMS) cobas® MRSA/SA Test utilizes real-time polymerase chain reaction (PCR) for the detection of Methicillin resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus (SA) DNA from nasal swab specimens collected in MSwab medium to aid in the prevention and control of MRSA and SA infections in healthcare settings. The cobas® MRSA/SA Test contains two major processes: (1) automated sample preparation to extract nucleic acids from the nasal swab specimens; (2) PCR amplification of target DNA sequences using MRSA and SA specific primers, and real-time detection of cleaved fluorescentlabeled MRSA and SA specific oligonucleotide detection probes. An Internal Control (IC), containing unrelated randomized DNA sequence, is added to all samples prior to automated sample preparation and is amplified and detected simultaneously with each sample to monitor the entire process. The MSwab Collection, Transport and Preservation System (Copan Flock Technologies S.r.1.) is used for specimen collection, transportation and storage of specimen for the cobas MRSA/SA Test. The cobas® MRSA/SA Test utilizes six reagent kits: 1. cobas® 4800 MRSA/SA Amplification/Detection Kit 2. cobas® 4800 MRSA/SA Controls and Cofactor Kit 3. cobas® 4800 System Wash Buffer Kit 4. cobas® 4800 System Lysis Kit 1 5. cobas 4800 System Internal Control Kit 1 6. cobas® 4800 System Sample Preparation Kit The cobas® 4800 System uses the cobas x 480 Instrument for sample preparation, and the cobas z 480 Analyzer for amplification and detection. Both the cobas x 480 Instrument and the cobas z 480 Analyzer are controlled by a computer workstation running the cobas® 4800 System Software.

The BD MAX™ MRSA XT assay performed on the BD MAX™ System is an automated qualitative in vitro diagnostic test for the direct detection of methicillin-resistant Staphylococcus aureus (MRSA) DNA from nasal swabs in patients at risk for nasal colonization. The test utilizes real-time polymerase chain reaction (PCR) for the amplification of MRSA DNA and fluorogenic target-specific hybridization probes for the detection of the amplified DNA. The BD MAX™ MRSA XT assay is intended to aid in the prevention and control of MRSA infections in healthcare settings. It is not intended to diagnose MRSA infections nor guide or monitor treatment for MRSA infections. A negative result does not preclude nasal colonization. Concomitant cultures are necessary to recover organisms for epidemiological typing or for further susceptibility testing.

The BD MAX™ System and the BD MAX™ MRSA XT assay are comprised of an instrument with associated hardware and accessories, disposable microfluidic cartridges, master mixes, unitized reagent strips, extraction reagents, and sample buffer tubes. The instrument automates sample preparation including target lysis, DNA extraction and concentration, reagent rehydration, and target nucleic acid amplification and detection using real-time PCR. The assay includes a Sample Processing Control (SPC) that is present in the Extraction Tube. The SPC monitors DNA extraction steps, thermal cycling steps, reagent integrity and the presence of inhibitory substances. The BD MAX™ System software automatically interprets test results. A test result may be called as MRSA NEG, MRSA POS or MRSA UNR (Unresolved)] based on the amplification status of the target and of the Sample Processing Control. IND (Indeterminate) or INC (Incomplete) results are due to BD MAX™ System failure.

The BD MAX™ StaphSR assay performed on the BD MAX™ System is an automated qualitative in vitro diagnostic test for the direct detection and differentiation of Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) DNA from nasal swabs in patients at risk for nasal colonization. The test utilizes realtime polymerase chain reaction (PCR) for the amplification of MRSA/SA DNA and fluorogenic target-specific hybridization probes for the detection of the amplified DNA. The BD MAX™ StaphSR assay is intended to aid in the prevention and control of MRSA and SA infections in healthcare settings. It is not intended to diagnose MRSA or SA infections nor guide or monitor treatment for MRSA/SA infections. A negative result does not preclude nasal colonization. Concomitant cultures are necessary to recover organisms for epidemiological typing or for further susceptibility testing.

The BD MAX™ System and the BD MAX™ StaphSR assay are comprised of an instrument with associated hardware and accessories, disposable microfluidic cartridges, master mixes, unitized reagent strips, extraction reagents, and sample buffer tubes. The instrument automates sample preparation including target lysis, DNA extraction and concentration, reagent rehydration, and target nucleic acid amplification and detection using real-time PCR. The assay includes a Sample Processing Control (SPC) that is present in the Extraction Tube. The SPC monitors DNA extraction steps, thermal cycling steps, reagent integrity and the presence of inhibitory substances. The BD MAX™ System software automatically interprets test results. A test result may be called as [SA NEG MRSA NEG (negative)], [SA POS, MRSA POS (MRSA positive)], [SA POS, MRSA NEG (SA positive)] or [SA UNR, MRSA UNR (Unresolved)] based on the amplification status of the target and of the Sample Processing Control. IND (Indeterminate) or INC (Incomplete) results are due to BD MAX™ System failure.

MRSA/SA ELITe MGB® is a qualitative in vitro diagnostic test for the direct detection of Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) using DNA purified from nasal swabs. MRSA/SA ELITe MGB® is intended to aid in the prevention and control of MRSA infections in healthcare settings. It is not intended to diagnose, guide or monitor MRSA infections, or provide results of susceptibility to oxacillin/methicilliin. A negative result does not preclude MRSA/SA (Staphylococcus aureus) nasal colonization. Concomitant cultures are necessary to recover organisms for epidemiological typing or for further susceptibility testing. Special conditions for use statement(s): Prescription Use Only.

MRSA/SA ELITe MGB® is a real-time, multiplex polymerase chain reaction (PCR) assay for the in vitro qualitative detection of MRSA and SA DNA extracted from human nasal swab samples. In this system, sample preparation and amplification/real-time detection are completed on separate instruments. Sample processing is completed on the bioMérieux NucliSENS® easyMAG® instrument with bioMérieux NucliSENS Nucleic Acid Extraction Reagents according to the manufacturer's instructions. Following processing, the extracted sample is placed in the well of a 96 well plate to which "monoreagent" is added. The monoreagent contains the primers and probes for the genes of interest and the internal control combined with master mix. The assay is performed on an Applied Biosystems 7500 FAST Dx System that consists of the 7500 FAST Dx instrument, a personal computer, 96-well plates and seals. The total system run time is 150 minutes consisting of 60 minutes for sample processing and about 90 minutes for the real time amplification and detection steps. The instrument never comes into contact with any fluids within the 96-well plate. Each disposable plate is intended to test up to 96 samples, controls or any mixture thereof. The 96-well plates are not re-usable and are specific to the system. The kit contains enough reagents for 100 reactions. One positive and one negative control are required for each PCR run; a Negative Processing Control and a Positive Processing Control are recommended to be run in each extraction run. The design of the assay includes systems to identify both the gene responsible for methicillin resistance and for a conserved portion of a gene unique to S. aureus. Thus, for a true "MRSA," both targets will be identified in roughly equal proportions. Results are determined by using an algorithm that compares output. Cq, from the cycler (called Ct in the output from the cvcler.) The algorithm is implemented for automatic results determination by analyzing the output Cq with ELITe MGB® software.

The Cepheid® Xpert® MRSA/SA Blood Culture Assay, performed on the GeneXpert® Instrument Systems, is a qualitative in vitro diagnostic test intended for the detection of Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) DNA directly from positive blood cultures. The assay utilizes automated real-time polymerase chain reaction (PCR) for the amplification of MRSA/SA specific DNA targets and fluorogenic target-specific hybridization probes for the real-time detection of the amplified DNA. The assay is performed directly on positive blood culture samples from BD BACTEC™ Plus Aerobic/F, BacT/ALERT® SA (Standard Aerobic) or VersaTREK REDOX 1® (aerobic) blood culture bottles that are determined by Gram Stain as Gram Positive Cocci in Clusters (GPCC) or as Gram Positive Cocci in singles (GPC). The Xpert MRSA/SA Blood Culture Assay is indicated for use in conjunction with other laboratory tests, such as culture, and clinical data available to the clinician as an aid in the detection of MRSA/SA from positive blood cultures. Subculturing of positive blood cultures is necessary to recover organisms for susceptibility testing or for epidemiological typing. The Cepheid Xpert MRSA/SA Blood Culture Assay is not intended to monitor treatment for MRSA/SA infections.

The Cepheid Xpert® MRSA/SA Blood Culture Assay (Xpert MRSA/SA Blood Culture Assay) is a rapid, automated DNA test for the simultaneous qualitative detection of MRSA and SA DNA directly from blood culture bottle specimens that are detected as positive for microbial growth and shown to contain Gram Positive Cocci by Gram stain. The primers and probes in the Xpert MRSA/SA Assay detect nucleic acid sequences of the staphylococcal protein A (spa), the gene for methicillin/oxacillin resistance (mecA), and staphylococcal cassette chromosome (SCCmec) inserted in the SA chromosomal attB site. The test includes a Sample Processing Control (SPC) to control for adequate processing of the target bacteria and to monitor the presence of inhibitor(s) in the PCR assay. The Probe Check Control (PCC) verifies reagent rehydration, PCR tube filling in the cartridge, probe integrity, and dye stability. The specimen for testing with the Xpert MRSA/SA Blood Culture Assay consists of an aliquot taken from a positive blood culture bottle. Using one of the disposable fixed 50 µL volume transfer pipettes provided with the test kit, an aliquot of the positive blood culture is transferred into a single-use tube of Elution Reagent, also provided with the kit. The Elution Reagent is briefly vortexed and the entire content is transferred to the "S" chamber of the disposable fluidic cartridge (the Xpert MRSA/SA Blood Culture Assay cartridge), after which the cartridge is ready to place on the instrument. The assay is performed on the Cepheid GeneXpert Instrument Systems, which automate and integrate sample purification, nucleic acid amplification of the target sequences in simple or complex samples using real-time PCR. The systems consist of an instrument, personal computer, and preloaded software for running the tests and viewing the results. The GeneXpert Instrument Systems require the use of single-use disposable cartridges that hold the PCR reagents and host the PCR process. Because the cartridges are self-contained, crosscontamination between samples is minimized. In this platform, additional sample preparation, amplification, and real-time detection are all fully-automated and completely integrated. The Xpert MRSA/SA Blood Culture Assay performed on the GeneXpert Instrument Systems provides results in approximately 60 minutes. The GeneXpert Instrument Systems, comprised of the GeneXpert Dx Systems and the GeneXpert Infinity Systems, have 1 to 80 randomly accessible modules, depending upon the instrument, that are each capable of performing separate sample preparation and real-time PCR tests. Each module contains a syringe drive for dispensing fluids (i.e., the syringe drive activates the plunger that works in concert with the rotary valve in the cartridge to move fluids between chambers), an ultrasonic horn for lysing cells or spores, and a proprietary I-CORE® thermocycler for performing real-time PCR and detection.