(240 days)
No
The description details a molecular diagnostic assay using NASBA and molecular beacons with automated result calculation based on fluorescence signal curves. There is no mention of AI or ML in the device description or performance studies.
No.
Explanation: The device is an in vitro diagnostic test for the direct detection of MRSA from nasal swabs. Its intended use is as a screening tool to aid in the prevention and control of MRSA infections. It is explicitly stated that the device is "not intended to diagnose, guide or monitor treatment for MRSA infections". Therefore, it is not a therapeutic device.
Yes
The "Intended Use / Indications for Use" section explicitly states "The NucliSENS EasyQ® MRSA assay is a qualitative in vitro diagnostic test for the direct detection of methicillin-resistant Staphylococcus aureus (MRSA)..."
No
The device description explicitly states that the assay is performed on the NucliSENS EasyQ® platform, which includes hardware components such as the Analyzer, Incubator II, Computer, Monitor, and Printer, in addition to the software.
Yes, this device is an IVD (In Vitro Diagnostic).
The "Intended Use / Indications for Use" section explicitly states: "The NucliSENS EasyQ® MRSA assay is a qualitative in vitro diagnostic test for the direct detection of methicillin-resistant Staphylococcus aureus (MRSA) from nasal swabs in patients at risk for nasal colonization."
The "Device Description" also reiterates: "The NucliSENS EasyQ® MRSA assay is a qualitative in vitro diagnostic test for the direct detection of methicillin-resistant Staphylococcus aureus (MRSA) from nasal swabs."
N/A
Intended Use / Indications for Use
The NucliSENS EasyQ® MRSA assay is a qualitative in vitro diagnostic test for the direct detection of methicillin-resistant Staphylococcus aureus (MRSA) from nasal swabs in patients at risk for nasal colonization. The NucliSENS EasyQ® MRSA assay is performed on the NucliSENS EasyQ® platform.
The test utilizes NASBA™ (nucleic acid sequence-based amplification) coupled with molecular beacons (sequence-specific fluorescent probes) to detect the presence of MRSA DNA.
The NucliSENS EasyQ® MRSA assay is used as a screening tool to aid in the prevention and control of MRSA infections in health care institutions.
The NucliSENS EasyQ® MRSA 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.
Product codes
NQX, OOI
Device Description
The NucliSENS EasyQ® MRSA assay is a qualitative in vitro diagnostic test for the direct detection of methicillin-resistant Staphylococcus aureus (MRSA) from nasal swabs.
The process involves:
- Specimen Collection: A dry flocked swab is used to collect a specimen from the anterior nares and transported to the laboratory in its container.
- Lysis: The swab is introduced into a lysis tube (containing Proclin solution with glass beads) and bacteria are recovered by manual rotation.
- Concentration: Bacteria in suspension are concentrated by centrifugation.
- Mechanical Lysis: The bacterial pellet is subjected to mechanical lysis on a Genie 2 vortex machine, followed by heating at 95 °C for 2 minutes.
- Amplification Mixture: Five microliters of the raw lysate are added to the NASBA™ amplification mixture, which contains a restriction enzyme, DNA sequence-specific primers, and molecular beacons. The amplification mixture reagents include lyophilized white spheres (primers, molecular probes, inhibition control, NASBA™ reagents like nucleotides, DTT, KCI, MgCl2, carbohydrate) and lyophilized orange spheres (restriction enzyme, Bovine Serum Albumin, carbohydrate).
- Digestion and Denaturation: The MRSA DNA is digested by the restriction enzyme and denatured in the EasyQ® Incubator.
- Enzyme Addition and Amplification: NASBA™ enzymes (lyophilized blue sphere containing AMV-RT, RNase H, T7 RNA polymerase, Bovine Serum Albumin) are added for amplification of the DNA targets by NASBA™ in the EasyQ® Analyzer.
- Simultaneous Amplification and Detection: Amplification and detection are performed simultaneously in a dedicated fluorescence reader, the NucliSENS EasyQ® Analyzer.
- Detection Principle: Amplification is detected by sequence-specific molecular beacons, which fluoresce upon binding to their target.
- Closed Tube Format: The assay is run in a closed tube format to minimize contamination risk.
- Reagent Quantity: The kit contains enough reagents for 48 reactions, allowing up to 44 specimens (plus 2 required NASBA™ controls and 2 recommended specimen processing controls) to be tested in a single run within 3 hours.
- Result Calculation: Result calculation is performed automatically via dedicated operator software (EasyQ Director and assay protocol) based on the analysis of fluorescence signal curves measured by the NucliSENS EasyQ® Analyzer. A qualitative output (MRSA positive, MRSA negative or invalid) is reported to users.
- Controls: An inhibition control (IC) is present in the reaction mix. The kit includes two NASBA™ controls (blank and positive control). Positive and negative controls for specimen preparation are recommended but not provided in the kit.
- Targets: The assay amplifies two targets simultaneously: the SCCmec cassette junction and the mecA gene, requiring both targets to be detected for a positive MRSA result to reduce false positives.
The system includes the NucliSENS EasyQ® Analyzer, NucliSENS EasyQ® Incubator II, NucliSENS EasyQ® Computer, Monitor, Printer, and NucliSENS EasyQ® Director Software 2.6.
Mentions image processing
Not Found
Mentions AI, DNN, or ML
Not Found
Input Imaging Modality
Not Found
Anatomical Site
nasal swabs
Indicated Patient Age Range
The clinical study included adult patients (≥ 21 years) and pediatric patients (Child: 2 years -
§ 866.1640 Antimicrobial susceptibility test powder.
(a)
Identification. An antimicrobial susceptibility test powder is a device that consists of an antimicrobial drug powder packaged in vials in specified amounts and intended for use in clinical laboratories for determining in vitro susceptibility of bacterial pathogens to these therapeutic agents. Test results are used to determine the antimicrobial agent of choice in the treatment of bacterial diseases.(b)
Classification. Class II (performance standards).
0
NucliSENS Easy Q MRSA
MAY 2 0 2011
510(k) SUMMARY
This summary of 510(k) safety and effectiveness information is being submitted in accordance with the requirements of SMDA 1990 and 21 CFR 807.92.
The assigned 510(k) number is: K102740
Name of device
NucliSENS EasyQ® MRSA Assay, including the following components:
Reagents
NucliSENS EasyQ® MRSA
Instrumentation and Software
NucliSENS EasyQ® MRSA assay protocol software included in the NucliSENS EasyQ® MRSA assay kit NucliSENS EasyQ® Director Software 2.6 NucliSENS EasyQ® Analyzer NucliSENS EasyQ® Incubator II
Classification
Device Class: Class 2
Assay Reagent System:
SYSTEM, NUCLEIC ACID AMPLIFICATION TEST, Common/Classification Name: DNA, METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS, DIRECT SPECIMEN
. Product code: NQX
Assay Instrumentation and Software System:
Common/Classification Name: INSTRUMENTATION FOR CLINICAL MULTIPLEX TEST SYSTEMS
Product code: OOI
Premarket Notification submitter:
| Company Name:
Company Address: | bioMérieux, Inc.
100 Rodolphe Street
Durham, NC 27712 |
|------------------------------------|--------------------------------------------------------------------------------------|
| Contact:
Telephone #:
FAX #: | Jocelyn Jennings, Senior Manager, Regulatory Affairs
919-620-2894
919-620-2548 |
Preparation Date: September 20, 2010
1
NucliSENS Easy O MRSA
Image /page/1/Picture/1 description: The image shows the logo for bioMerieux. The logo consists of the word "BIOMERIEUX" in a blocky, sans-serif font. Above the text is a solid black circle with a thin line extending vertically upwards from the top of the circle and downwards through the middle of the text.
Device to which equivalence is claimed
The assay reagent system which is the subject of this submission is claimed equivalent to the BD GeneOhm test, which received 510(k) clearance from FDA as the IDI-MRSA™, #K033415, cleared on 18-Mar-2004.
The instrumentation and software in this submission are claimed equivalent to the instrumentation and software reviewed by FDA as the NucliSENS EasyQ Enterovirus v1.1, K093383, cleared on 6-July-2010.
Intended Use of the Device
The NucliSENS EasyQ® MRSA assay is a qualitative in vitro diagnostic test for the direct detection of methicillin-resistant Staphylococcus aureus (MRSA) from nasal swabs in patients at risk for nasal colonization. The NucliSENS EasyQ® MRSA assay is performed on the NucliSENS EasyQ® platform.
The test utilizes NASBA™ (nucleic acid sequence-based amplification) coupled with molecular beacons (sequence-specific fluorescent probes) to detect the presence of MRSA DNA.
The NucliSENS EasyQ® MRSA assay is used as a screening tool to aid in the prevention and control of MRSA infections in health care institutions.
The NucliSENS EasyQ® MRSA 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.
Description of the Device
- A dry flocked swab, that is not pre-moistened, is used to collect a specimen from the 1. anterior nares. After collection the swab is transported to the laboratory in its container for specimen processing.
-
- The swab is introduced into the lysis tube and bacteria are recovered from the swab by rotating the swab manually.
- ತೆ. Bacteria in suspension in the lysis tube are concentrated by centrifugation.
- After carefully discarding the supernatant, the remaining bacterial pellet is subjected to র্বা mechanical lysis on a Genie 2 vortex machine. The lysate is subsequently heated at 95 °C for 2 minutes.
- Five microliters of the raw lysate are added to the NASBA™ amplification mixture that 5. contains the restriction enzyme, DNA sequence-specific primers and beacons.
- Next, the MRSA DNA is digested by the restriction enzyme and denatured in the EasyQ® રે. Incubator.
- The NASBA™ enzymes are then added for amplification of the DNA targets by NASBA™ 7. in the EasyQ® Analyzer.
-
- Amplification and detection are performed simultaneously in a dedicated fluorescence reader, the NucliSENS EasyQ® Analyzer.
- റ്റ് Amplification is detected by means of sequences-specific probes, which fluoresce upon binding of the probe to its target.
-
- The assay is run in a closed tube format minimizing any risk for amplicons contamination.
2
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NucliSENS Easy O& MRSA
-
- The kit contains enough reagents for 48 reactions. Up to 44 specimens (plus 2 reguired NASBA™ controls and 2 recommended specimen processing controls) can be tested in a single run within 3 hours.
-
- Result calculation is performed automatically via dedicated operator software and is based on the analysis of fluorescence signal curves measured by the NucliSENS EasyQ® Analyzer. Qualitative output (MRSA positive, MRSA negative or invalid) is reported to users.
- An inhibition control (IC) is present in the reaction mix to detect inhibitory specimen. 13.
- The NucliSENS EasyQ® MRSA assay includes reagents for the run controls: two 14. NASBA™ controls (blank and positive control) that must be included in each run.
-
- Positive and neqative controls for specimen preparation are recommended for each EasyQ amplification run; these specimen controls are not provided in the kit. Strains suitable for use as specimen negative control (SNC) and the six specimen positive controls (SPC) are described. These strains allow the operator to perform quality control for all components of the test, including all primers and probes in the kit. The specimen positive controls may be rotated in series leading to one SPC and one SNC per run.
Reagents and Test Components
Assay Kit Components
| Component | Composition | Number of tubes and tube
description | Caps Color code |
|--------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------|------------------------|
| LYS Tub
(lysis tube) | Proclin solution with glass
beads* | 48 tubes
1150 ul per tube | Uncolored cap
tubes |
| REAGENT spheres
sachet
(amplification/detection
reagents) | Lyophilized white sphere:
primers, molecular
probes
inhibition control:
●
non-infectious DNA
NASBA™ reagents
●
(nucleotides, DTT.
KCI, MgCl2)
carbohydrate
Lyophilized orange sphere:
Restriction enzyme
●
Bovine Serum
Albumin**
carbohydrate | 6 tubes in foil pack with silica gel
desiccant
2 spheres per tube (white and
orange) | Blue cap tubes |
| ENZ I sphere sachet
(enzyme reagents) | Lyophilized blue sphere :
AMV-RT, RNase H.
●
T7 RNA polymerase
Bovine Serum
●
Albumin** | 6 tubes in foil pack with silica gel
desiccant
1 sphere per tube (blue) | Red cap tubes |
| REAGENT dil | Reagent spheres diluent
(Tris/HCI, KCI, DMSO,PVP ) | 2 tubes.
600 ul per tube | Blue cap tubes |
Table 1: Components of NucliSENS EasyQ® MRSA
3
NucliSENS Easy Q* MRSA
Image /page/3/Picture/1 description: The image shows the logo for BIOMÉRIEUX. The logo consists of the company name in a stylized font, with a vertical line running through the middle of the name. Above the name is a solid black circle with a small line extending upwards from the top.
| Component | Composition | Number of tubes and tube
description | Caps Color code |
|------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------|-----------------|
| ENZdil | Enzyme sphere diluent (Sorbitol,
Bovine Serum Albumin**, Proclin) | 2 tubes.
350 μl per tube | Red cap tubes |
| NW | NASBATM water with proclin for
dissolution of the CONTROL+
sphere and for the NASBATM blank | 2 tubes.
1500 μl per tube | White cap tubes |
| CONTROL+ sphere
sachet | NASBATM positive control DNA:
lyophilized sphere containing
non infectious DNA plasmids | 4 tubes in foil pack with silica gel
desiccant
1 sphere per tube (white) | White cap tubes |
| TBSTR
CPSTR | 8 tubes strip: 6 pieces
8 cap strip: 12 pieces | | Not applicable |
| CD-ROM containing
Instructions for use for
NucliSENS EasyQ®
MRSA assay, Assay
protocols, sample login
file and worksheets | MRSA SPC US 1.0 for the
specimen positive control,
MRSA SNC US 1.0 for the
specimen negative control,
MRSA PC US 1.0 for the positive
control,
MRSA BLK US 1.0 for the blank
control,
MRSA US 1.0 for clinical
specimen(s).
Controls_MRSA_US_1.0.sl for
the sample login file.
MRSA Worksheet Specimen
Preparation.
MRSA Worksheet Amplification
and Detection.
MRSA Worksheet Preparation of
Specimen Controls | | |
(*) The volume of beads can vary which does not affect the test performance.
(**) Warnings and precautions: Bovine Serum Albumin is included in Enzyme diluents, Reagent sphere and Enzyme sphere. Certified knowledge of the origin and/or sanitary state of the animals does not totally guarantee the absence of transmissible pathogenic agents. It is therefore recommended that these products be treated as potentially infectious and handled observing the usual safety precautions (do not ingest or inhale).
Caution: Handle with care; treat as a potentially infectious material.
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NucliSENS Easy Q& MRSA
| Product | Catalogue number |
|---|---|
| NucliSENS EasyQ® System | |
| It includes the following: | |
| NucliSENS EasyQ® Analyzer | |
| NucliSENS EasyQ® Incubator V2 | |
| NucliSENS EasyQ® Computer | |
| Monitor | |
| Printer | |
| NucliSENS EasyQ® Director Software 2.6 | |
| Mini Microcentrifuge | |
| Operator Manuals | 4700016 |
Assay Components Sold Separately by bioMérieux
Additional Materials
| Product | Catalogue number |
|---|---|
| Micro tubes; 1.5 ml (500 x) | 200294 |
| 0.2 ml 8-tube strips (125 pcs) | 285048 |
| 0.2 ml 8-tube caps (125 pcs) | 285051 |
| EasyQ® Tube tray holder | 45685049 |
| EasyQ® Cap Installing Tool (Capping aid) | 45685050 |
| Pipetting aid | 45685207 |
Other
- . Sterile dry flocked swab with transport tube (bioMerieux reference 280101)
- Sterile water in ampoule compatible with densitometer ●
- 2 ml and 10 ml sterile tubes (for preparation of the specimen controls) ●
- Densitometer
- Standards for calibration of densitometer ●
- Vortex Genie 2 with MOBIO horizontal 24-positions adaptor only (bioMerieux reference ● for the MOBIO adapter 270677)
- . Vortex Genie 2 for mixing individual tubes
- Vortex with flathead dimpled adaptor
- Ice or cooling block for 1.5 ml tubes .
- . High speed centrifuge (capable of reaching speeds of up to 16 000 g) for 1.5 ml tubes
- . Calibrated monochannel micropipettes with variable volume: 5 to 1,000 ul delivery volume
- Sterile-packaged, disposable, aerosol resistant tips (with filter) ●
- Disposable gloves, powderless .
- . Tabletop centrifuge for 1.5 ml test tube
- Waste container with cap (e.g. 50 ml tubes or zip-bags)
- 95 °C dry bath (calibrated) for incubation of 1.5 ml tubes (range of calibration e.g.±1.7°C) ●
- . Timer
- Sterile 1.5 ml tubes ●
- Mucin from submaxillary gland (Mucin type I-S from Sigma reference M3895-1G)
5
- MRSA strains: MREJ type ii (ATCC 43300*), MREJ type iii (ATCC BAA-39*), MREJ type . iv (ATCC BAA-40*), MREJ type v (ATCC BAA-2096*), MREJ type vii (ATCC BAA-2095*) and MREJ type xii (ATCC BAA-2094*)
- MSSA strain (ATCC 29213*) ●
- TSA agar plate .
- . Blood agar plate
- Applicator .
- Strains can be purchased from ATCC or other vendors.
Assay Instruments and Software
The instrumentation and software for the NucliSENS EasyQ System, including the EasyQ Analyzer, EasyQ Incubator, and Director 2.5 software, received FDA clearance in June 2008 as part of the 510(k) submission for the NucliSENS EasyQ Enterovirus v1.0 test (submission K063261).
The instrumentation and software for the NucliSENS EasyQ System was re-submitted as K093383 in November 2009, to comply with an FDA request. In K093383, the EasyQ Incubator was replaced by the EasyQ Incubator II, and Director software 2.5 was replaced by Director software 2.6.
Instrumentation and software for the NucliSENS EasyQ MRSA test is largely unchanged from the system as reviewed in K093383.
Instrumentation: the use of the vortex adaptor plate is new for the EasyQ MRSA test and is documented in this submission (see BTL065234). No changes have been made to the EasyQ Incubator, to the PC (personal computer) or the PC monitor sold for use with the EasyQ Analyzer.
One change has been made to the EasyQ Analyzer. The Analyzer design includes the capacity for 8 filter pairs; however only 2 of the 8 positions were utilized in conjunction for the NucliSENS EasyQ Enterovirus v1.0 test (for detection of FAM and ROX beacons)'. For the NucliSENS EasyQ MRSA test, a third filter pair is used to enable detection of beacons labeled with Cy5.
Software: The Director 2.6 software is unmodified versus the version submitted in K093383. Note that Director software was already configured to enable use of up to 5 filter pairs, dependent on parameters incorporated in the assay protocol developed for each assay application
The assay protocol distributed with the EasyQ MRSA kit was developed using the same basic paradigm as for the Enterovirus v1.1 assay protocol in K093383. However whereas the Enterovirus v1.1 assay protocol was customized from the QL1 algorithm, the MRSA assay protocol was customized from a different base algorithm, T4. Full software design documentation to support the MRSA assay protocol is therefore included in this submission.
- 1 Per BTL036512 Product Design Requirements Labsystems Fluorescence Reader and related Software (Revision of Doc. 8730.99.5126 00), as submitted in K093383, the EasyQ Analyzer had 2 filtersets: PR23 Filters (Product Requirement 23, page 7) Current available filtersets: Fluorescein Ex 485(14±2) (half bandwidth) Em 538±(25±3) ROX Ex 584±(16±2) Em 620±(15±5) Blocking factor outside HBW 10-3 Filter specifications should enable to meet crosstalk & performance specification
- d Per BTL013130 PRD NucliSens EasyQ Director Software, NucliSens EasyQ Director IV (= Product Requirements Document, Director 2.5, as submitted in K093383), per requirement PRD1.1.4 on p. 10: "The software will offer support for assays that use more than two fluorescent labels up to 8 labels."
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NucliSENS Easy Q* MRSA
SUBSTANTIAL EQUIVALENCE INFORMATION
Predicate device name(s): BD GeneOhm MRSA Assay
Predicate device 510(k) number(s) K033415
Comparison with predicate
The EasyQ MRSA test is claimed substantially equivalent to the BD GeneOhm™ MRSA Assay (K033415).
| Similarities and Differences | |||
|---|---|---|---|
| ltem | EasyQ MRSA | Predicate | |
| Intended Use | Qualitative diagnostic screening for | ||
| MRSA in nasal swab specimens | Same | ||
| Specimen Type | Nasal swab | Same | |
| Technological Principles | Manual specimen processing with | ||
| automated amplification, detection, | |||
| analysis and reporting of results | Same | ||
| Amplification technology | NASBA (Nucleic Acid Sequence- | ||
| Based Amplification) | PCR (Polymerase Chain Reaction) | ||
| Detection technology | Fluorogenic target-specific | ||
| hybridization | Same | ||
| Instrument System | EasyQ® System | Cepheid SmartCycler® | |
| Specimen Processing | Manual processing in single 1.5-mL | ||
| tube with glass beads using vortex and | |||
| centrifuge | Manual processing in two microtubes | ||
| using glass beads, vortex and centrifuge | |||
| Analysis and reporting of | |||
| results | Automated using diagnostic software | ||
| (EasyQ Director and assay protocol) | |||
| on the EasyQ® System | Automated using diagnostic software on | ||
| the Smart Cycler® | |||
| DNA Target Sequence(s) | 1 - Sequence incorporating the | ||
| insertion site of Staphylococcal | |||
| Cassette Chromosome mec (SCCmec) | |||
| at orfX junction, with 6 variant sets | |||
| primers and probes to target 7 MREJ | |||
| types i, ii, iii, iv, v, vii, xii (target | |||
| sequences for MREJ i and ii are | |||
| identical) | 1- Same | ||
| 2 - mecA gene | 2- Not applicable | ||
| Probes | Molecular Beacons | Same | |
| Controls | Internal control in each test, plus 2 | ||
| external controls (positive and blank) | |||
| supplied in kit, plus 2 specimen | |||
| controls (MRSA and MSSA) | |||
| recommended for each run | One internal reagent control and | ||
| external positive and negative controls | |||
| required per run |
Similarities and differences between the tests are outlined below:
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Standard/Guidance Document Referenced (if applicable):
Not applicable
Test Principle:
Specimen Preparation:
Collection
` Trained personnel should perform the collection of swabs and care should be taken to obtain adequate specimen as outlined below:
Open the tube and remove the flocked swab from its empty tube.
Insert the flocked swab into the patient's nostril; rotate the swab 5 times to obtain a sample. Use swab dry without pre-moistening.
Insert the same swab into the second nostril and repeat the sampling.
Insert the swab back into its dry transport tube.
Label the plastic transport tube with patient identification.
Storage
Specimens once collected can be stored for a period:
- up to 4 days, both at room temperature or at 2-8 ℃ before testing .
- up to 1 day at room temperature followed by 3 days at 2-8 ℃ before testing.
Nucleic acid amplification and detection
DNA NASBA ™
In DNA NASBA™, the bacterial DNA is first digested with a restriction enzyme and then copies of RNA derived from a target DNA sequence are manifold multiplied by isothermal amplification by the combined activities of 3 enzymes: Avian Myeloblastosis Virus Reverse Transcriptase (AMV-RT). Bacteriophage T7 RNA Polymerase (T7 RNA Pol). and RNase H, along with both ribo- and deoxyribo-nucleotides (rNTPs and dNTPs) and the cofactors dithiothreitol (DTT), MgCl2, KCI and DMSO. This process is described below. The figure also shows the differences between NASBA™ targeted to DNA templates versus RNA templates.
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Image /page/8/Figure/2 description: The image shows the title of a figure. The title is "Figure 1. DNA vs RNA NASBA™". The title is written in a clear, sans-serif font and is centered on the image. The text is black and the background is white.
To start the DNA NASBA™ process, the restriction enzyme Hae III cuts the target DNA near the binding site of primer 1 (P1). Afterwards, the reaction mixture is heated to 95°C to denature the linearized DNA and to inactivate the restriction enzyme. Subsequently, the reaction mixture is cooled down to 41°C and the primer P1 anneals to the positive strand of the target DNA. This starts the "linear phase" of the NASBA™ reaction where double-stranded DNA amplicons with a T7 promoter tail are generated.
In the cyclic phase of the NASBA™ reaction, the T7 promoter tail on the cDNA target amplicon serves as a binding site for T7 RNA Pol. which then transcribes from the cDNA amplicon using rNTP's to generate a negative strand RNA copy. A single original positive strand target sequence (with T7 tail applied) will serve as a template for multiple RNA copies as the reaction proceeds.
Detection with Molecular Beacons
Molecular beacons are hairpin structure-forming single-stranded oligonucleotides labelled at one end with a fluorescent dye named the fluorophore and at the other end with a quencher. In the absence of complementary target amplicons, the hairpin structure closes, bringing the fluorophore and quencher into close proximity, and as a result no fluorescent signal is emitted. In the presence of target amplicons, the beacon hybridizes to its complementary target instead of forming an internal hairpin structure. Once the beacon opens, the quencher and fluorophore separate, quenching ceases and fluorescence is emitted.
9
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Image /page/9/Figure/2 description: The image shows a diagram of a molecular beacon assay. Part A shows a molecular beacon with a fluorophore (F) and a quencher (Q). Part B shows the target RNA molecular beacon hybridization. Part C shows the target RNA molecular beacon hybrid with the fluorophore not quenched.
Figure 2: Principle of Molecular beacon detection
MRSA assay
The NucliSENS EasyQ® MRSA test utilizes NASBA™ (nucleic acid sequence-based amplification) coupled with molecular beacons (sequence-specific fluorescent probes) to detect the presence of MRSA DNA in nasal swabs from patients at risk for nasal colonization with MRSA. Amplification and detection occur simultaneously in the EasyQ Analyzer.
The NucliSENS EasyQ® MRSA is developed for amplification of two targets . simultaneously: the SCCmec cassette junction and the mecA gene.
False positive results have been reported in the literature with tests that detect the cassette junction only due to a phenomenon known as "mecA dropout" leading to methicillin-sensitive Staphylococcus aureus strains that lost the mecA gene but still harbour the cassette junction. Such strains are detected as MRSA positive by such tests. (See reference 1 in the Bibliography section).
The NucliSENS EasyQ® MRSA will report a MRSA positive result only if both . targets, the SCCmec cassette junction and the mecA gene, are detected, thus reducing the risk of false positive detection.
Primers and beacons in the kit are complementary to the SCCmec cassette junction sequences of MREJ types i-v, vii, and xii.
Explanation of the assay
A dry flocked swab, that is not pre-moistened, is used to collect a specimen from the anterior nares. After collection the swab is transported to the laboratory in its container for specimen processing.
- The swab is introduced into the lysis tube and bacteria are recovered from the swab by rotating the swab manually.
- . Bacteria in suspension in the lysis tube are concentrated by centrifugation.
10
Image /page/10/Picture/1 description: The image shows the logo for bioMerieux. The logo consists of the word "BIOMERIEUX" in a sans-serif font, with a vertical line extending from the top of the "E" in "MERIEUX" upwards. Above the word is a black circle with a thin vertical line extending upwards from the top of the circle.
After carefully discarding the supernatant, the remaining bacterial pellet is subjected to mechanical lysis on a Genie 2 vortex machine. The Ivsate is subsequently heated at 95 °C for 2 minutes.
Five microliters of the raw Ivsate are added to the NASBA™ amplification . mixture that contains the restriction enzyme. DNA sequence-specific primers and beacons.
Next. the MRSA DNA is digested by the restriction enzyme and denatured in . the EasyQ® Incubator.
The NASBA™ enzymes are then added for amplification of the DNA tarqets . bv NASBA™ in the EasyQ® analyzer.
Amplification and detection are performed simultaneously in a dedicated fluorescence reader, the NucliSENS EasyQ® Analyzer.
Amplification is detected by means of sequence-specific probes which . fluoresce upon binding of the probe to its target.
. The assay is run in a closed tube format minimizing any risk for amplicons contamination.
. The kit contains enough reagents for 48 reactions. Up to 44 specimens (plus 2 required NASBA™ controls and 2 recommended specimen processing controls) can be tested in a single run within 3 hours.
. Result calculation is performed automatically via dedicated operator software and is based on the analysis of fluorescence signal curves measured by the NucliSENS EasyQ® Analyzer. Qualitative output (MRSA positive, MRSA negative or invalid) is reported to users.
. An inhibition control (IC) is present in the reaction mix to detect inhibitory specimen.
The NucliSENS EasyQ® MRSA assav includes reagents for the run controls: . two NASBA™ controls (blank and positive control) that must be included in each run
. Positive and neqative controls for specimen preparation are recommended for each EasyQ® amplification run; these specimen controls are not provided in the kit. Strains suitable for use as specimen negative control (SNC) and the six specimen positive controls (SPC) are described in the package insert. These strains allow the operator to perform quality control for all components of the test, including all primers and probes in the kit. The specimen positive controls may be rotated in series with one SPC per run.
Performance Characteristics
Interfering substances
A study was conducted with potentially interfering substances encountered in nasal swabs. Substances tested were chemical substances that can either be naturally present in the nasal cavity or that can be artificially introduced into the nasal cavity.
Accordingly, the following substances were tested and evaluated: blood, mucin, azelastine HCI (Astelin). Eucalvptus globulus/ kalium bichromicus (Sino Fresh). phenylephrine HCI (Neo-synephrine), cromolyn sodium (NasalChrom), Zicum Gluconium (Zicam gel), oxymetazolinė HCl (Vicks Sinex), Triamcinolone acetonide (Nasacort), mometasone furoate (Nasonex).
The following drugs / biological substances have been shown to interfere with the performance of the assay:
- . Astelin (50 ul per swab)
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- . Sino Fresh (50 ul per swab)
- Nasal chrom (50 ul per swab) .
- . Zicam (50 ul per swab)
- Blood (15 ul and 50 ul per swab).
In the context of the clinical trials, blood was reported on nasal swabs for 20/1238 (1,6%) specimens, one of which yielded an invalid result.
Biological interference
An excess of methicillin-sensitive Staphylococcus aureus or methicillin-resistant Staphylococcus epidermidis or methicillin-sensitive Staphylococcus epidermidis did not interfere with the detection of MRSA or with the reporting of MRSA negative swabs.
Analytical sensitivity: Limits of Detection (LOD) for strains of MRSA with different types of MREJ
The analytical sensitivity of the NucliSENS EasyQ® MRSA assay was determined using clinical nasal matrices and various strains of MRSA representing the seven types of MREJ detected by the test. Bacterial suspensions with a bacterial input ranging from 10 to 1000 CFU per swab were tested in 24 replicates of each input.
The limit of detection was defined as the input corresponding to the 95 % Hit Rate predicted by statistical analysis using a probit regression model.
The estimated type-specific LoDs were further confirmed with two batches of reagents. The claimed type-specific LoD summarized below correspond to the higher concentrations claimed from these two studies, i.e. either real input determined by plating and counting bacteria colony forming units in the confirmation study, or predicted concentrations by the probit regression model.
| MREJ
type | SCCmec
type | LOD
(CFU/swab) |
|--------------|----------------|-------------------|
| i | I | 410 |
| ii | II | 227 |
| iii | III | 493 |
| iv | III | 234 |
| V | IV | 200 |
| vii | III | 482 |
| xii | V | 182 |
LoD for seven MRSA types
Analytical specificity
Sequence alignments
Primers and probes were designed for optimal specificity by comparative nucleic acid sequence analysis of genetically related strains of Staphylococci and of unrelated species known to be present in nasal specimens.
Using this sequence analysis, the combination of MRSA primers and beacons was shown to be highly specific to MRSA strains.
Experimental data
Fresh cultures from 100 phylogenetically related S.aureus and members of the nasal commensal flora were tested at an input of 7.5X10E6 CFU/swab (26 strains of methicillin-resistant coagulase negative staphylococci, 29 strains of methicillin-
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sensitive coaqulase-negative staphylococci. 25 strains of methicillin-sensitive coagulase-positive staphylococci including 20 strains of MSSA, 20 strains other than staphylococci belonging to the nasal commensal flora including 1 strain of Grampositive rods, 10 strains of Gram-negative rods, 7 strains of non staphylococci Grampositive cocci, 1 strain of Gram-negative cocci, 1 strain of yeast).
One strain of MSSA was initially detected positive for the cassette junction due to contamination. This MSSA strain was re-tested and found negative for the cassette junction.
All the strains were detected MRSA negative except two strains when tested with mecA positive clinical samples.
Analytical Reactivity
Sequence alignments
Genomic nucleic acid sequences of 319 strains of MRSA were found in public databases and were analyzed for inclusivity with the NucliSENS EasyQ® MRSA assay. Sequence analysis indicated that 314 strains were theoretically covered by the design of primers and beacons (98.4%).
Experimental data
Fresh cultures from 193 MRSA strains were tested at an input of 3 times the LOD. The 193 strains comprised:
- Strains of MRSA belonging to the following MREJ types: 21 MREJ type i, 119 . MREJ type ii, 16 MREJ type iii, 2 MREJ type iv, 1 MREJ type v, and 2 MREJ types vii. In addition, strains belonging to the new MREJ types ix, xiii, and xiv were also included.
- . Strains MRSA belonging to each of the SCCmec types I, II, III, IV, V and VI.
- Strains belonging to the worldwide most prevalent MRSA clones. .
- . Strains of MRSA belonging to the PFGE types USA 100, 200, 300, 400, 500, 600, 700, 800, 1000 and 1100.
- . Strains of MRSA characterized for MIC to oxacillin including both homogeneous highly resistant strains with high oxacillin MIC and heterogeneous resistant strains with lower oxacillin MIC (2-8 µg/ml) values.
- Strains of MRSA recently isolated in USA hospitals.
The NucliSENS EasyQ® MRSA assay accurately detected 184 of the 193 isolates of MRSA tested, 95.3%.
Precision within-laboratory and between-laboratory
The precision of the NucliSENS EasyQ MRSA assay was evaluated using artificial samples consisting of human nasal matrix spiked with MRSA strains at 3 different inputs. The precision study was determined with respect to the complete assay procedure, comprising all steps from the extraction of the specimen from the swab to the final result.
The panel of tested samples was comprised of three different bacterial inputs, tested in 3 replicates per run: "High Negative" samples corresponding to approximately 0.03 x LOD, "Low Positive" samples corresponding to approximately 1.00 x LOD and "Moderate Positive" samples corresponding to approximately 4.82 x LOD.
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The precision was analyzed by determining for each bacterial input the percentage of correct NucliSENS EasyQ MRSA test results based on the expected outcome.
A "within-laboratory" precision study was performed at one internal site over 12 days. with 2 operators, using 2 instruments and 2 lots of reagents.
The overall percent agreement with the expected outcome was 90.3% for the high negative input. 98.6% for the low positive input and 100% for the moderate positive input in the table below. The table below also shows for the maxLambda mecA and maxLambda cassette junction values (internal measurements to determine the final assay result). the overall means, standard deviations, and coefficients of variation obtained for testing with the different bacterial inputs.
Within-Laboratory Variation
| Sample Input1 | % Agreement | 95% CI | MaxLambda mecA | MaxLambda cassette junction | ||||
|---|---|---|---|---|---|---|---|---|
| High Negative (HN) | 90.3% (65/72) | 81.0-96.0% | 2.669 | 0.0592 | 2.2 | 1.034 | 0.0723 | 7.0 |
| Low Positive (LP) | 98.6% (71/72) | 92.5-99.9% | 2.641 | 0.0782 | 3.0 | 1.578 | 0.2178 | 13.8 |
| Moderate Positive (MP) | 100% (72/72) | 95.0-100% | 2.680 | 0.0564 | 2.1 | 1.996 | 0.1498 | 7.5 |
| Total Agreement | 96.3% (208/216) | 92.8-98.4% |
approx. 0.03 x LOD 'HN =
LP= approx. 1.00 x LOD
MP= approx. 4.82 x LOD
A "between-laboratory" precision study was performed at 3 sites (1 internal site and 2 external sites in the US), over 6 days, with 2 operators at each site. 1 instrument at each site and 2 lots of reagents.
The overall percent agreement with the expected outcome was 93.5% for the high neqative input, 87.0% for the low positive input, and 100% for the moderate positive input in the table below. The table below also shows for the maxLambda mecA and maxLambda cassette junction values the overall means. standard deviations, and coefficients of variation obtained for testing with the different bacterial inputs.
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NucliSENS Easy Q* MRSA
Between-Laboratory Variation
| Sample
Input1 | Site 11 | Site 2 | Site 3 | Total
Agreement | MaxLambda mecA | | | MaxLambda cassette junction | | |
|------------------------------|--------------------|--------------------|--------------------|---------------------------------------|----------------|--------|-----|-----------------------------|--------|------|
| | %
Agreement | %
Agreement | %
Agreement | %
Agreement
and 95% CI | Mean | SD | %CV | Mean | SD | %CV |
| High
Negative
(HN) | 94.4%
(34/36) | 100%
(36/36) | 86.1%
(31/36) | 93.5%
(101/108)
87.1 -
97.4% | 2.650 | 0.0662 | 2.5 | 1.024 | 0.0558 | 5.4 |
| Low Positive
(LP) | 85.7%
(31/36) | 75.0%
(27/36) | 100%
(36/36) | 87.0%
(94/108)
79.2 -
92.7% | 2.631 | 0.0837 | 3.2 | 1.347 | 0.2707 | 20.1 |
| Low Positive
2 (LP2) | 100%
(36/36) | 97.2%
(35/36) | 100%
(36/36) | 99.1%
(107/108)
94.9 -
99.9% | 2.557 | 0.0995 | 3.9 | 1.735 | 0.2405 | 13.9 |
| Moderate
Positive
(MP) | 100%
(36/36) | 100%
(36/36) | 100%
(36/36) | 100%
(108/108)
96.6 - 100% | 2.670 | 0.1119 | 4.2 | 1.816 | 0.2550 | 14.0 |
| Total
Agreement | 95.1%
(137/144) | 93.1%
(134/144) | 96.5%
(139/144) | 94.9%
(410/432)
92.4 -
96.8% | | | | | | |
'HN = approx. 0.03 x LoD
approx. 1.00 x LoD
approx. 2.00 x LoD LP= LP2=
MP= approx. 4.82 x LoD
Between-Lot Variation ( Between-Laboratory)
| Sample Input1 | Lot 1
%
Agreement | Lot 2
%
Agreement | Total
Agreement
% Agreement
and 95% CI | MaxLambda mecA | | | MaxLambda
cassette junction | | |
|------------------------------------------------------|-------------------------|-------------------------|-------------------------------------------------|----------------|--------|-----|--------------------------------|--------|------|
| High Negative
(HN) | 94.4%
(51/54) | 92.6%
(50/54) | 93.5%
(101/108)
87.1 - 97.4% | 2.650 | 0.0662 | 2.5 | 1.024 | 0.0558 | 5.4 |
| Low Positive
(LP) | 90.7%
(49/54) | 83.3%
(45/54) | 87.0%
(94/108)
79.2 - 92.7% | 2.631 | 0.0837 | 3.2 | 1.347 | 0.2707 | 20.1 |
| Low Positive
2 (LP2) | 98.1%
(53/54) | 100%
(54/54) | 99.1%
(107/108)
94.9 - 99.9% | 2.557 | 0.0995 | 3.9 | 1.735 | 0.2405 | 13.9 |
| Moderate
Positive (MP) | 100%
(54/54) | 100%
(54/54) | 100%
(108/108)
96.6 -100% | 2.670 | 0.1119 | 4.2 | 1.816 | 0.2550 | 14.0 |
| Total
Agreement | 95.8%
(207/216) | 94.0%
(203/216) | 94.9%
(410/432)
92.4 - 96.8% | | | | | | |
| 1HN = approx. 0.03 x LoD LP2= approx. 2.00 x LoD | | | | | | | | | |
"HN = approx. 0.03 x LoD LP= approx. 1.00 x LoD approx. 2.00 x LoD approx. 4.82 x LoD
MP=
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| | MaxLambda mecA | | | MaxLambda
cassette junction | | | | | |
|---------------------------|--------------------|--------------------|------------------------------------|--------------------------------|--------|-----|-------|--------|------|
| Sample Input1 | Lot 1 | Lot 2 | Total
Agreement | Mean | SD | %CV | Mean | SD | %CV |
| | %
Agreement | %
Agreement | % Agreement
and 95% CI | | | | | | |
| High Negative
(HN) | 91.7%
(33/36) | 88.9%
(32/36) | 90.3%
(65/72)
81.0 - 96.0% | 2.669 | 0.0592 | 2.2 | 1.034 | 0.0723 | 7.0 |
| Low Positive
(LP) | 100%
(36/36) | 97.2%
(35/36) | 98.6%
(71/72)
92.5 - 99.9% | 2.641 | 0.0782 | 3.0 | 1.578 | 0.2178 | 13.8 |
| Moderate
Positive (MP) | 100%
(36/36) | 100%
(36/36) | 100%
(72/72)
95.0 -100% | 2.680 | 0.0564 | 2.1 | 1.996 | 0.1498 | 7.5 |
| Total
Agreement | 97.2%
(105/108) | 95.4%
(103/108) | 96.3%
(208/216)
92.8 - 98.4% | | | | | | |
Between lot variation (Within -Laboratory)
HN = approx. 0.03 x LoD LP= approx. 1.00 x LoD
MP= approx. 4.82 x LoD
Carry-Over Contamination
To evaluate the risk of carry-over contamination for the NucliSENS EasyQ MRSA assay during the processes of sample preparation, amplification and detection, five MRSA NASBA runs were performed with alternating high MRSA positive (5x106 CFU/lysis tube) and MRSA negative samples (negative for both the mecA and the SCCmec cassette). Artificial samples were used consisting of lysis tubes with frozen matrix from clinical swabs, the positive artificial samples being spiked with a strain of MRSA at the concentration indicated above.
In total, 105 high positive and 105 MRSA negative samples were tested divided over 5 EasyQ runs.
The results of this carry-over contamination study showed that no cross-over contamination was observed amongst 103 valid negative specimens results surrounded by high positive specimens (105 MRSA negative samples were tested, but 2 were classified as invalid and thus discarded).
Thus, the workflow and design of the assay were shown to be robust against carry-over contamination.
Clinical Performance ·
Clinical Study Design
Performance characteristics of the NucliSENS EasyQ® MRSA assay were determined in a multicenter prospective investigational study employing 7 geographically diverse institutions in the US, eches propositive investigational study chiploying 7 geographically their species and 1980, 1998, 1998, 1998, 1998, 1998, 1998, 1998, 1998, 1998, 198 collection-only sites sent their specimens to one of the testing sites. The NucliSENS EasyQ MRSA assay was compared to the reference enriched culture, the most sensitive culture method. Subjects included patients from healthcare institutions at risk for colonization with MRSA and routine screening cultures. Each subject was enrolled in the study only once. Subjects taking antibiotics for eradication of MRSA colonization or for treatment of MRSA infection in the 7 days
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prior to specimen collection, patients that had contraindications to nasal swab collection or children under 2 years old were excluded from the trial.
Two (2) nasal swabs were prospectively collected from each patient; One (1) swab was tested
with the NucliSENS Easyand 1 swab with the reference culture method. For the enriched culture method, a swab was directly inoculated into an enrichment broth consisting of trypticase soy broth (TSB) with 6.5 % NaCl and incubated for 18-24 hours at 35 -37 ℃. The enrichment broth was then streaked onto a blood agar plate (BAP) and incubated for 24-48 hours at 35 -37 °C. The plate was then examined and suspect S. aureus colonies were confirmed with a Gram stain and latex agglutination test. Confirmed S. aureus colonies were tested for methicillin resistance using the cefoxitin disk test as described in CLSI M2A9 and CLSI M100 S17.
Performance (sensitivity and specificity) of the NucliSENS EasyQ® MRSA test was calculated relative to the reference culture results.
Overall Clinical Study Results: Agreement of NucliSENS EasyQ® Test with Reference Culture
Results from the NucliSENS EasyQ® MRSA assay compared with results from the reference culture method are presented in the tables below.
There were 144 final evaluable specimens that were positive for MRSA by the reference culture
method. There were 14' specimens that were invalid for NucliSENS EasyQ ® MRSA; 1 positive by reference culture and 13 were negative by reference culture.
NucliSENS EasyQ ® MRSA had a clinical sensitivity of 95.8%, a clinical specificity of 96.8%, a Positive Predictive Value (PPV) of 79.7% and a Negative Predictive Value (NPV) of 99.4%.
A total of 1355 nasal specimens were collected of which 1238 had reportable results and are included in the analysis. There were 117 specimens excluded due to non-compliance with the clinical protocol.
| Reference Culture* | |||||||
|---|---|---|---|---|---|---|---|
| Total | |||||||
| NucliSENS | |||||||
| EasyQ® MRSA | 137 | રૂર્ણ | 172 | ||||
| 1046 | 1052 | ||||||
| Total | 143 | 1081 | 1224 |
Results Comparing NucliSENS EasyQ® MRSA with Reference Culture.
*mecA mediated oxacillin resistance using 30 µg cefoxitin disk
َ invalids not included in the calculation
Performance Parameters - NucliSENS EasyQ® MRSA versus Reference Culture
| | Parameter
Estimate1 | 95% Confidence
Interval |
|--------------------------------------------------------------------|------------------------|----------------------------|
| Sensitivity: EasyQ vs. Reference Culture (137/143) | 95.8% | 91.1-98.4% |
| Specificity: EasyQ vs. Reference Culture (1046/1081) | 96.8% | 95.5-97.7% |
| EasyQ Positive Predictive Value with Reference Culture (137/172) | 79.7% | 72.9-85.4% |
| EasyQ Negative Predictive Value with Reference Culture (1046/1052) | 99.4% | 98.8-99.8 % |
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NucliSENS Easy Q8 MRSA
Positive Predictive Value and Negative Predictive Value of the NucliSENS EasyQ MRSA Assay Compared to the Reference Culture Method and Prevalence of MRSA at Individual Sites.
| Site | MRSA
Prevalence | PPV
NucliSENS
MRSA | 95% CI | NPV
NucliSENS MRSA | 95% CI |
|-------|--------------------|--------------------------|------------|-----------------------|------------|
| 1 | 10.0% (20/200) | 67.9% (19/28) | 47.7-84.1% | 99.4% (168/169) | 96.8-99.9% |
| 2 | 9.1% (39/427) | 83.3% (35/42) | 68.6-93.0% | 99.0% (378/382) | 97.3-99.7% |
| 3 | 33.6% (50/149) | 85.7% (48/56) | 73.8-93.6% | 98.9% (90/91) | 94.0-99.9% |
| 4 | 10.3% (6/58) | 85.7% (6/7) | 42.1-99.6% | 100% (45/45) | 92.1-100% |
| 5 | 8.1% (24/296) | 77.4% (24/31) | 58.9-90.4% | 100% (265/265) | 98.6-100% |
| 6 | 6.5% (3/46) | 100% (3/3) | 29.2-100% | 100% (43/43) | 91.8-100% |
| 7 | 3.2% (2/62) | 40.0% (2/5) | 5.3-85.3% | 100% (57/57) | 93.7-100% |
| Total | 11.6% (144/1238) | 79.7% (137/172) | 72.9-85.4% | 99.4% (1046/1052) | 98.8-99.8% |
Clinical Study Results: Agreement of NucliSENS EasyQ® MRSA Test with Reference Culture for Adults
Of the 1238 nasal specimens that had reportable results, 877 were collected from adult patients.
Results from the NucliSENS EasyQ® MRSA assay with adult specimens compared wi from the reference culture method are presented in tables 13 and 14 below.
There were 114 final evaluable specimens that were positive for MRSA by the reference culture
method. There were 14' specimens that were invalid for NucliSENS EasyQ® MRSA; 1 positive by reference culture and 13 were negative by reference culture.
NucliSENS EasyQ® MRSA had a clinical sensitivity of 94.7% and a clinical specificity of 96.5%.
Results Comparing NucliSENS EasyQ® MRSA with Reference Culture for Adult Specimens
| Reference Culture* | Total | ||
|---|---|---|---|
| + | - | ||
| NucliSENS EasyQ® MRSA | 107 | 26 | 133 |
| - | 6 | 724 | 730 |
| Total | 113 | 750 | 863 |
- mecA mediated oxacillin resistance using 30µg cefoxitin disk
1 invalids not included in the calculation
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| | Parameter
Estimate | 95% Confidence
Interval |
|------------------------------------------------------------------|-----------------------|----------------------------|
| Sensitivity: EasyQ vs.Reference Culture (107/113) | 94.7% | 88.8-98.0% |
| Specificity: EasyQ vs. Reference Culture (724/750) | 96.5% | 95.0-97.7% |
| EasyQ Positive Predictive Value with Reference Culture (107/133) | 80.5% | 72.7-86.8% |
| EasyQ Negative Predictive Value with Reference Culture (724/730) | 99.2% | 98.2-99.7% |
Performance Parameters - NucliSENS EasyQ® MRSA versus Reference Culture for Adult Specimens
Clinical Study Results: Agreement of NucliSENS EasyQ® MRSA Test with Reference Culture for Pediatrics
Pediatric samples included specimens from Child, Adolescent, and Transitional Adolescent patients. Of the 1238 nasal specimens that had reportable results, 361 were collected from pediatric patients. Results from the NucliSENS EasyQ® MRSA assay with pediatric specimens compared against results from the reference culture method are presented in the tables below. Age distribution is presented in the table below.
There were 30 final evaluable specimens that were positive for MRSA by the reference culture method. NucliSENS EasyQ® MRSA had a clinical sensitivity of 100% and a clinical specificity of 97.3%.
Results Comparing NucliSENS EasyQ® MRSA Assay with Reference Culture for Pediatric Specimens
| Reference Culture* | |||
|---|---|---|---|
| + | - | Total | |
| NucliSENS | |||
| EasyQ® MRSA | 30 | 9 | 39 |
| 0 | 322 | 322 | |
| Total | 30 | 331 | 361 |
mecA mediated oxacillin resistance using 30μg cefoxitin disk
Performance Parameters - NucliSENS EasyQ® MRSA versus Reference Culture for Pediatric Specimens
| | Parameter
Estimate | 95% Confidence
Interval |
|------------------------------------------------------------------|-----------------------|----------------------------|
| Sensitivity: EasyQ vs. Reference Culture (30/30) | 100% | 88.4-100% |
| Specificity: EasyQ vs. Reference Culture (322/331) | 97.3% | 94.9-98.8% |
| EasyQ Positive Predictive Value with Reference Culture (30/39) | 76.9% | 60.7-88.9% |
| EasyQ Negative Predictive Value with Reference Culture (322/322) | 100% | 98.9-100% |
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Age Distribution of Patients
| | Child (2years -