The BD MAX™ Cdiff Assay performed on the BD MAX™ System is an automated in vitro diagnostic test for the direct, qualitative detection of the Clostridium difficile toxin B gene (tcdB) in human liquid or soft stool specimens from patients suspected of having C. difficile infection (CDI). The test. performed directly on the specimen, utilizes real-time polymerase chain reaction (PCR) for the amplification of C. difficile toxin B gene DNA and fluorogenic target-specific hybridization probes for the detection of the amplified DNA. The BD MAX ™ Cdiff Assay is intended to aid in the diagnosis of CDI.

Device Description

The BD MAX™ System and the BD MAX™ Cdiff 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 Ivsis. 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 result may be called as NEG (negative), POS (positive) or 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.

AI/ML Overview

BD MAX™ Cdiff Assay - Acceptance Criteria and Study Findings

The BD MAX™ Cdiff Assay is an automated in vitro diagnostic test for the direct, qualitative detection of the Clostridium difficile toxin B gene (tcdB) in human liquid or soft stool specimens. The assay is intended to aid in the diagnosis of C. difficile infection (CDI).

1. Table of Acceptance Criteria and Reported Device Performance

The provided document details various analytical and clinical performance studies, but explicit "acceptance criteria" for minimum performance thresholds (e.g., "Sensitivity must be >= 90%") are not stated in a direct, consolidated table. However, the reported performance metrics can be inferred as meeting the implicit acceptance criteria for the submission to be cleared.

Here's a summary of the reported device performance from the provided text, focusing on key metrics:

Performance Metric	Reported Device Performance (BD MAX™ Cdiff Assay)
Clinical Performance (vs. Reference Method: Direct Culture + Enriched Culture)
Sensitivity	87.7% (265/302) (95% CI: 83.6%, 91.0%)
Specificity	96.8% (1469/1517) (95% CI: 95.8%, 97.6%)
Positive Predictive Value (PPV)	83.5% (95% CI: 79.4%, 87.1%)
Negative Predictive Value (NPV)	97.7% (95% CI: 97.0%, 98.4%)
Clinical Performance (vs. Direct Culture)
Positive Percent Agreement (PPA)	96.5% (194/201) (95% CI: 93.0%, 98.3%)
Negative Percent Agreement (NPA)	92.7% (1507/1625) (95% CI: 91.4%, 93.9%)
Comparison to FDA-cleared Molecular Assay 1
Positive Percent Agreement (PPA)	99.1% (95% CI: 94.9%-99.8%)
Negative Percent Agreement (NPA)	97.4% (95% CI: 95.7%-98.4%)
Comparison to FDA-cleared Molecular Assay 2
Positive Percent Agreement (PPA)	95.5% (95% CI: 92.1%-97.5%)
Negative Percent Agreement (NPA)	98.8% (95% CI: 97.9%-99.3%)
Analytical Sensitivity (LoD)	LoD ranged from 125 to 265 CFU per loop for tested strains (lowest concentration at which 95% of replicates tested positive).
Analytical Inclusivity	Correctly identified 62 of 64 toxigenic C. difficile strains (~3xLoD). 2 strains produced low signal/false-negative in 1/5 replicates.
Analytical Specificity	Produced negative results for 6/6 non-tcdB C. difficile strains, 30/30 other Clostridium strains, and 95/98 other bacterial strains.
Reproducibility (Overall % Agreement for LP, MP, Neg samples)	100% (both Lot-to-Lot and Site-to-Site)
Unresolved Rate (after repeat testing)	0.5% (10/1844) (95% CI: 0.3%, 1.0%)

2. Sample Size and Data Provenance

Test Set (Clinical Performance Studies):
- Clinical Performance (vs. Reference Method): 1819 compliant and reportable results from 2071 initial soft or liquid stool specimens.
- Clinical Performance (vs. Direct Culture): 1826 compliant and reportable results.
- Comparison Studies: 2013 specimens tested across two external sites (specific breakdown per comparator assay: 647 for one and 1366 for the other).
- Data Provenance: Multi-site prospective investigational study from six investigational centers. The document does not specify countries of origin, but the submitting company is Canadian. The study was prospective, as specimens were from "patients suspected of having C. difficile infection for which diagnostic tests were indicated and ordered."
Training Set: The document does not provide specific details on a separate "training set" for algorithm development. This is common for molecular diagnostic assays where the "training" (e.g., selection of primers/probes, optimization of PCR conditions) is inherent in the assay's design and analytical validation, rather than a distinct machine learning training phase.

3. Number of Experts and Qualifications for Ground Truth

Ground Truth for Clinical Performance (Reference Method): The ground truth was established by a "Comparative Reference Method consisting of direct culture complemented by enriched culture." The anaerobic culture was used to isolate C. difficile, followed by confirmation of isolate identification and a "Tissue Culture Cytotoxicity Assay to determine the toxigenicity of the isolate." This process typically involves trained microbiology laboratory personnel, but the specific number and qualifications of "experts" (e.g., clinical microbiologists, laboratory directors) involved in establishing the final ground truth from this multi-step process are not explicitly stated in the document.
Ground Truth for Analytical Studies (e.g., LoD, Inclusivity, Specificity): For analytical studies, ground truth was based on known concentrations of bacterial strains (CFU/mL or genomic copies/mL) or known presence/absence of certain organisms, established through standard laboratory methods of quantification and identification. No "experts" in the sense of clinical reviewers are typically involved in establishing these analytical truths.

4. Adjudication Method for the Test Set

The document does not describe a formal adjudication method (e.g., 2+1, 3+1 reviewer consensus) by human experts for the clinical test set results. The ground truth for the clinical performance was established by a "Comparative Reference Method" (direct culture + enriched culture + toxigenicity testing). Discordant results between the BD MAX™ Cdiff Assay and this Reference Method were further investigated:

"27 of 48 False Positive BD MAX™ Cdiff specimens were also found to be positive using another commercially available FDA-cleared RT-PCR assay targeting the C. difficile tcdB gene."
"32 of 37 False Negative BD MAX™ Cdiff specimens, were also found to be negative using another commercially available FDA-cleared RT-PCR assay targeting the C. difficile tcdB gene."
This "further investigation" serves as a form of resolution for discordant cases but is not a traditional multi-reader "adjudication" process using human interpretation of images or clinical data.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was described. The device is an automated in vitro diagnostic test that provides a qualitative (positive/negative) result, meaning there is no human "reader" in the loop for interpreting the assay's output that would then be compared to human performance with or without AI assistance. The study compares the device's performance against a reference method and other FDA-cleared molecular assays.

6. Standalone Performance

Yes, a standalone (algorithm only without human-in-the-loop performance) study was done. The entire clinical and analytical performance evaluation describes the performance of the BD MAX™ Cdiff Assay as a standalone device. The assay automates sample preparation, nucleic acid amplification, and detection, with the BD MAX™ System software automatically interpreting test results as NEG (negative), POS (positive), or UNR (unresolved).

7. Type of Ground Truth Used

Clinical Performance Studies: The ground truth was based on a "Comparative Reference Method" which primarily relied on culture-based methods (direct and enriched anaerobic culture to isolate C. difficile) combined with a Tissue Culture Cytotoxicity Assay to determine the toxigenicity of the isolated strains. This represents a combination of microbiological culture and a functional assay (outcome of bacterial toxin activity on cells).
Analytical Performance Studies (LoD, Inclusivity, Specificity): The ground truth was based on known characterized bacterial strains and their concentrations, determined by standard microbiological quantification methods.

8. Sample Size for the Training Set

The document does not specify a distinct "training set" sample size in the context of the device's development or a machine learning algorithm. For molecular diagnostic assays like this, the "training" involves the scientific development and optimization of the assay components (primers, probes, reaction conditions) performed by molecular biologists and R&D scientists, rather than a separate data-driven training phase for an AI model.

9. How the Ground Truth for the Training Set Was Established

As described above, no explicit "training set" with established ground truth in the machine learning sense is detailed. The assay's design and optimization (analogous to "training" in AI development) would have utilized known positive and negative controls, characterized bacterial strains, and various concentrations to perfect the real-time PCR parameters and ensure accurate detection of the tcdB gene. This process involves standard laboratory validation techniques rather than human expert annotation for ground truth.

Summary

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510(k) Summary

APR 0 2 2013

ﺮ ﺍﻟ

March 28, 2013

	BD Diagnostics BD MAX™ Cdiff Assay
Submitted by:	GeneOhm Sciences Canada Inc. (BD Diagnostics)2555 Boul. Parc-TechnologiqueQuebec (Quebec), CanadaG1P 4S5
Contact:	Patricia Dionne, Ph.D.
Device:
510(k) Number:	K130470
Trade Name:	BD MAX™ Cdiff Assay
Common Name:	Clostridium difficile tcdB detection assay
Type of Test:	Qualitative Nucleic Acid Amplification Test for C. difficile toxin B genefrom liquid or soft stool specimens
Classification:	II
Regulation Name:	Clostridium difficile Toxin Gene Amplification Assay
Regulation Number:	866.3130
Product Code:	OZN, OOI
Panel:	Microbiology (83)
Predicate Device:	BD GeneOhm™ Cdiff Assay
Predicate 510(k) number:	K081920

Intended Use:

Indication for Use:

The BD MAX™ Cdiff Assay performed on the BD MAX™ System is an automated in vitro diagnostic test for the direct, qualitative detection of the Clostridium difficile toxin B gene (todB) in human liquid or soft stool specimens from patients suspected of having C. difficile infection (CDI). The test,

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performed directly on the specimen. utilizes real-time polymerase chain reaction (PCR) for the amplification of C. difficile toxin B gene DNA and fluorogenic target-specific hybridization probes for the detection of the amplified DNA. The BD MAX™ Cdiff Assay is intended to aid in the diagnosis of CDI.

Special Conditions for Use Statement:

For prescription use

Special Instrument Requirements:

The BD MAX™ System

Device Description:

Test Principle:

The BD MAX™ Cdiff Assay performed on the BD MAX™ System is an automated in vitro diagnostic test for the direct, qualitative detection of the Clostridium difficile toxin B gene (todB) in human liguid or soft stool specimens from patients suspected of having C. difficile infection (CDI).

A liquid or soft stool specimen is collected and transported to the laboratory. For testing, a disposable 10µL inoculating loop is dipped into the stool material and the contents dispersed into a BD MAX™ Cdiff Sample Buffer Tube. The Sample Buffer Tube is closed with a septum cap and vortexed. A worklist is created and the Sample Buffer Tube, the BD MAX™ Cdiff unitized reagent strip and the BD MAX™ PCR Cartridge are loaded onto the BD MAX™ System.

Following enzymatic cell lysis, the released nucleic acids are captured on magnetic beads. The beads, with the bound nucleic acids, are washed using Wash Buffer and the nucleic acids are eluted by heat in Elution Buffer. Eluted DNA is neutralized using Neutralization Buffer and transferred to a Master Mix to rehydrate PCR reagents. After reconstitution, the BD MAX™ System dispenses a fixed volume of PCR-ready solution containing extracted nucleic acids into the BD MAX™ PCR Cartridge. Microvalves in the BD MAX™ PCR Cartridge are sealed by the system prior to initiating PCR to contain the amplification mixture, thus preventing evaporation and contamination.

The amplified DNA targets are detected using hydrolysis (TaqMan®) probes, labeled at one end with a fluorescent reporter dye (fluorophore), and at the other end, with a quencher moiety. Probes labeled with different fluorophores are used to detect tcdB and SPC amplicons in two different

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optical channels of the BD MAX™ System. When the probes are in their native state, the fluorescence of the fluorophore is quenched due to its proximity to the quencher. However, in the presence of target DNA, the probes hybridize to their complementary sequences and are hydrolyzed by the 5-3' exonuclease activity of the DNA polymerase as it synthesizes the nascent strand along the DNA template. As a result, the fluorophores are separated from the quencher molecules and fluorescence is emitted. The amount of fluorescence detected in the two optical channels used for the BD MAX™ Cdiff Assay is directly proportional to the quantity of the corresponding probe that is hydrolyzed. The BD MAX™ System monitors these signals at each cycle of the PCR and interprets the data at the end of the program to provide a final result.

Substantial Equivalence:

Table 1 shows the similarities and differences between the BD MAX™ Cdiff Assay and the predicate device.

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Item	Device	Predicate
SIMILARITIES
Intended Use	The BD MAX™ Cdiff Assay performedon the BD MAX™ System is anautomated in vitro diagnostic test forthe direct, qualitative detection of theClostridium difficile toxin B gene ( tcdB )in human liquid or soft stool specimensfrom patients suspected of having C. difficile infection (CDI). The test,performed directly on the specimen,utilizes real-time polymerase chainreaction (PCR) for the amplification ofC. difficile toxin B gene DNA andfluorogenic target-specifichybridization probes for the detectionof the amplified DNA. The BD MAX™Cdiff Assay is intended to aid in thediagnosis of CDI.	The BD GeneOhm™ Cdiff Assay is arapid in vitro diagnostic test for thedirect, qualitative detection of C. difficile toxin B gene ( tcdB ) in humanliquid or soft stool specimens frompatients suspected of havingClostridium difficile -associated disease(CDAD). The test, based on real-timePCR, is intended for use as an aid indiagnosis of CDAD. The test isperformed directly on the specimen,utilizing polymerase chain reaction(PCR) for the amplification of specifictargets and fluorogenic target-specifichybridization probes for the detectionof the amplified DNA.
Mode ofdetection fortoxin B	Presence of the toxin B ( tcdB ) gene	Presence of the toxin B ( tcdB ) gene
SpecimenType	Liquid and soft stool specimens	Liquid and soft stool specimens
Assay Format	Amplification: PCRDetection: Fluorogenic target-specifichybridization	Amplification: PCRDetection: Fluorogenic target-specifichybridization
Interpretationof testresults	Automated (Diagnostic software of BDMAX™ system)	Automated (Diagnostic software ofSmartCycler® system)
DIFFERENCES
AnalysisPlatform	BD MAX™ System	SmartCycler® System
PCR SamplePreparation	Automated by the BD MAX™ System	Manual
DetectionProbes	TaqMan® Probe	Molecular Beacon Probe

Table 1: Substantial Equivalence Information

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Assay Controls	Specimen Processing Control (SPC)	Positive (DNA from Clostridium difficilebearing the tcdB gene ATCC 43255)
		Negative (DNA from Escherichia coliATCC 25922)
		Internal procedural control

Analytical Performance:

Precision

Within-laboratory precision was evaluated for the BD MAX™ Cdiff Assay at one (1) site. The Precision panel consisted of 5 sample categories in simulated sample matrix as follows:

Moderate Positive (MP): 2 5 x LoD .
. Low Positive (LP): 1- 2 x LoD
. High Negative 1:10 (HN1:10): 10-fold dilution of 1 x LoD
High Negative 1:100 (HN1:100): 100-fold dilution of 1 x LoD .
True Negative (Neg)

Testing was performed in duplicate, over 12 days, with 2 runs per day, by 2 technologists. Precision study results for Neq. LP and MP samples demonstrated 100% agreement. Precision study results for HN1:100 and HN1:10 demonstrated agreement of 95.8% and 58.3%, respectively. Precision performance was acceptable for the LP, MP, and Neg sample categories. No specific acceptance criteria were defined for either of the high negative sample categories.

Reproducibility

Reproducibility was evaluated with a panel that consisted of the same sample categories described for the Precision study. Samples in each category were tested in triplicate, on 5 distinct days, wherein each day 2 panels were tested by 2 technologists, at 3 clinical sites using 1 lot of reagents (Site-to-Site). One of these clinical sites participated in an extended study where 2 additional lots of reagents were tested (Lot-to-Lot). Results are shown for each sample category.

For Site-to-Site Reproducibility, the overall percent agreement was 100% for MP. LP and Neg categories. The Site-to-Site Reproducibility results demonstrated 92.2% and 50.0% negative agreement for HN1:100 and HN1:10 categories, respectively (Table 2).

For Lot-to-Lot Reproducibility, the overall percent agreement was 100% for MP, LP and Neg The Lot-to-Lot Reproducibility results demonstrated 96.7% and 64.4% negative categories. agreement for HN1:100 and HN1:10 categories, respectively (Table 3).

Site-to Site and Lot-to-Lot Reproducibility performance was acceptable for the LP, MP, and Neg sample categories. No specific acceptance criteria were defined for either of the high negative sample categories.

Lot-to-Lot and Site-to-Site quantitative reproducibility study results for positive and negative samples were stratified as follows (see Tables 2 to 5):

. Within run
Between runs within day .
. Between days within lot

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Between lots .

: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : and the comments of the country of

: .

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BD MAX™ Cdiff Assay
PreMarket Notification

			Table 2. Lot-to-Lot Quantitative Reproducibility	Stud	ട്ടResult	Lots100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000across	and Runs,Jays		and within Run \	Samefor Positiv	રેક	I
Free Property of Children Comments of Children	EP		Within Run		Between	Run within Day	Between Day within Lot		Between	Lof	Overal
Category------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	T	Mear	SD	%CV	SD	%CV	SD	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------%CV	SD	%C1	SD	00 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 -%CV
HN1:10	32	316.	101.89	32.2%	53.21	16.8%	0.00	0.0%	0.00	0.0%	114.95	36.4%
LP	90	748.6	67.05	22.3%	74.75	10.0%	21.14	2.8%	64.47	8.6%	195.18	26.1%
MP	90	975.6	201.66	20.7%	.8547	4.9%	41.24	4.2%	58.00	5.9%	219.14	22.5%
							I
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	vabus			Nithin Run	Rotwoon	Run within Nav	Batween Dav withinCollege of the comments of		Batween		Overa
	SDPA			Within Run		Between Run within DayComments of Children Colors of Children	tween Day within ﺍBet	Lot	Between	n Lot	Overal
Category	N	Mean	SD	%CV	SDAnd Address of Act Act Act Act Act Act Act Access And	%CV	SD	%CV	SD	%CV	SD	%CVmanagements of the first the first the first the first the first the first the first the first the first the first the first the first the first the first the first the first
HN1:10A	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------32	OCCUPOR COLORIOS COLLECTION34.4	0.73	2.1% _________________________________________________________________________________________________________________________________________________________________________	0.29	0.8%	0.00	0.0%	0.58	1.7%	0.97	2.8%
LP	90	32.8	0.74	2.3%	0.21	0.6%	0.00	0.0%	0.16	0.5%	0.78	2.4%
MP	90	32.1	0.80	2.5%	0.00	0.0%	0.00	0.0%	0.06	0.2%	0.80	Canadian and Canadian Canadian Canadian Canadian Canada Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Car2.5%
												And Analysis and Career of Children
Carles of Children Company of Children Company of Children Company of Children Comments of Children Comments of Children Comments of Children Comments of Children Comments of	SDPH			Within Run		Between Run within Day	Between Day within Lot			Between Lot	Overall
Category	N	Mean	SD	%CV	SD	%CV	SD	%CV	SD	%CV	SD	%AFBS AC%
HN1:10	32	3.7	1.37	37.3%	0.47	12.7%	0.00	0.0%	0.00	0.0%	1.45
LP	90	0.4	2.34	24.8%	0.89	9.5%	0.28	3.0%	0.89	9.4%	2.67	28.3%
MP	90	12.8	2.96	23.1%	0.72	5.6%	0.54	4.2%	1.36	10.6%	3.38	26.3%
	SDPA			Comment John AWithin Run	Between Run within Day		etween Day within L6	Lot		Between Lot		Overall
Category	1	Mean	SD	%CV	SD	%CV	SD	%CV	SD	%CV	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------SD	%CVProperty
HN1:100	87	29.0-	0.40	1.4%------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	0.00	0.0%	0.09	0.3%	0.40	.4%	0.57
HN1:10	ട്ക	29.0	0.29	1.0%	0.00	0.0%	0.05	0.2%	0.50	1.7%	0.58	5 %D %DF %D75 %D75
Neg	90	29.0	0.37	1.3%	0.00	0.0%	0.00	0.0%	0.43	.5%	0.57
												BANDACTORS
	SDPH------------------------------------------------------------------------------------------------------------------------------------------------------------------------------			Within Run		Between Run within Day	letween Day within. B	Lot	Between	Lot		Overall
Category	N	Mean	SD	%CV	SD	%CV	ട് പ്	%CV	SD	%CV	SD	%CV
HN1:100	87	89.5	6.58------------	9.5%	.97	2.8%	0.00	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------0.0%	4.10	5.9%1	8.00	11.5%
HN1:10	ક્ષ્ઠ	ಲ್ಲೂ ರಿ	7.72	11.2%	5.04	7.3%	0.00	0.0%	2.83	4.1%	9.64	14.0%
Neg	90	ﻨﺴﻴﺴﺘﻌﻠﻨﺖ ﺍﻟﻤﺴﺘﺸﻔﻴﻨﻴﺔ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺴﺘﺸﻔﻴﺔ ﺍﻟﻤﺘﺤﺪﺓ ﺍﻟﻤﺴﺘﻮﻯ ﺍﻟﻤﺴﺘﺸﻔﻴﺔ ﺍﻟﻤ89.5	6.56	9.4%	2.09	3.0%	0.00	0.0%	4.52	6.5%	8.23	11.8%

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MAX™ Cdiff Ass
Market Notificatio

13.4% 16.3% 13.8% %CV Overall 752.18 718.58 865.50 SD ble 3. Lot-to-Lot Quantitative Reproducibility Study Results across Lots, Days and Runs, and within Run for Negative Samples
8.5% 6.8% 9.2% %CV 455.55 361.57 498.52 SD 0.0% 0.0% 0.0% %CV 0.00 0.00 0.00 SD 4.1% 2.7% 8.2% %CV 219.72 148.59 432.84 SD 12.4% 10.0% 9.5% %CV 510.44 543.30 656.51 SD 5432.3 5361.3 Mean 5296.7 06 18
N 89 Category HN1:100 HN1:10 Neg

9.4% Neg

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able 4. Site-to-Site Quantitative Reproducibility Study Results for the Target across Sites, Days and Runs and within Run using one Lot
restive Samples

Overall

Between Site

Between Day within Site

Between Run within Day

Within Run

Category	N	Mean	SD	%CV	SD	%CV	SD	%CV	SD	%CV	SD	%CV
HN1:100	7	279.7	56.11	20.1%	0.00	0.0%	186.31	66.6%	0.00	0.0%	194.58	69.6%
HN1:10	45	314.7	151.79	48.2%	67.47	21.4%	0.00	0.0%	12.53	4.0%	166.58	52.9%
LP	90	948.8	149.65	15.8%	89.99	9.5%	0.00	0.0%	361.55	38.1%	401.51	42.3%
MP	90	1217.4	224.30	18.4%	150.77	12.4%	0.00	0.0%	374.72	30.8%	462.02	37.9%
	SDPA			Within Run		Between Run within Day		Between Day within Site		Between Site	Overall
Category	N	Mean	SD	%CV	SD	%CV	SD	%CV	SD	%CV	SD	%CV
HN1:100	7	33.4	2.17	6.5%	5.53	16.6%	0.00	0.0%	0.00	0.0%	5.94	17.8%
HN1:10	45	35.1	0.95	2.7%	0.20	0.6%	0.32	0.9%	0.55	1.6%	1.16	3.3%
LP	90	32.5	0.60	1.8%	0.00	0.0%	0.19	0.6%	0.45	1.4%	0.77	2.4%
MP	90	31.6	0.75	2.4%	0.19	0.6%	0.00	0.0%	0.26	0.8%	0.82	2.6%
	SDPH			Within Run		Between Run within Day		Between Day within Site		Between Site	Overall
Category	N	Mean	SD	%CV	SD	%CV	SD	%CV	SD	%CV	SD	%CV
HN1:100	7	3.9	0.23	5.9%	0.00	0.0%	2.99	76.5%	0.00	0.0%	2.99	76.7%
HN1:10	45	4.2	2.34	55.8%	0.96	23.0%	0.00	0.0%	0.00	0.0%	2.53	60.4%
LP	90	13.1	2.37	18.2%	1.36	10.4%	0.00	0.0%	5.28	40.4%	5.94	45.5%
MP	90	17.6	3.83	21.8%	2.42	13.7%	0.00	0.0%	5.50	31.3%	7.13	40.5%

alues shown are those obtained for the C. difficile target in the samples that gave a positive resu

21.8%

3.83

61.18

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BD MAX™ Cdiff Assay	PreMarket Notification
---------------------	------------------------

Table 5. Site-to-Site Quantitative Reproducibility Study Results across Sites, Days and Runs and within Run using one Lot for Negative
Samples'


etween00Within Rur	un within D	within Site
SD%CVA Brand Book Boom Add American A MARK ASDMear
62.2712.6%i631.46.5020.4------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	I
250.03------------------------------------------------------------------------------------------------------------------------------------------------------------------------------10.5%524.235006.5
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------204.88A MARK ALL A BRITACH A10.7%554.665166.0		------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	-------------------

	SDPA	------------	Within RunI		Between	Run within Day	Between	ו Day within Site------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	Between	Site	Overali
AAAAAAAAAAAAAAAAAACategory------------------------------------------------------------------------------------------------------------------------------------------------------------------------------		Mear	SD	%CV------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	SD	The state of the status and the commend of the first to the first to the first to the first the%CV	SD	%CV------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------SD	Land annual Access & Lawren & La%CV	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------SDI	%CV.
HN1:100l	83	28.81	0.35	LE E REAL I RESEARCHING MENT EXTERNAL MENTER AND1.2%	0.00	0.0%	0.00	I0.0%	0.18A LEAS - CALLER	0.6%------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------0.39	1.4%
HN1:10	45	A Comments of Children Comments of Children28.8	0.32------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	1.1%	0.00	0.0%	0.00	0.0%	0.16	0.5%	0.35	.2%
Neg	90	28.7------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	0.27	· 0.9%	0.00	0.0%	0.00	0.0%	0.14	0.5%	0.30	1.1%------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
		дости полнения принамента в компанских и компа комп	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	.	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	------	---------------------------------------------------------------------	I
A	SDPH	00 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 - 10 -	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------	Within Rur	Between	Run within DaA	etween0	SiteDay within	Between------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Active-And American Archively American American American A	Site	Overal	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Categor		Mean	------------------------------------------------------------------------------------------------------------------------------------------------------------------------------SD	%CV	SD	A-4-4-40-48-44-44-44-44-44-44-44-44-44-44-44-44-44-44-44-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4%CV	The first and the comments of the comments of the comments of the comments of the comments of the comments of the comments of the comments of the comments of the comments ofSD	%CVActually Addition Add	SD	%CV	SD	%CVA
HN1:100I	83	64.8I	-9.84	15.2%	0.00	0.0%	0.00BARRANT .	0.0%.	4.65	7.2%	10.89	16.8%
HN1:10	45	64.5	7.47I	11.6%	2.15	3.3%	0.00	0.0%	4.43	6.9%	8.94	3.9%
Neg	90	67.0	6.51	9.7%	2.40	3.6%	0.00	0.0%	6.55	9.8%	9.54	14.2%
		Calculated for the Specimen Processing Control of nega	I		Canada Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Cara Caative samples			.	CALL PROPERTY	.

10/19

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Second Derivative Peak Abscissa (SDPA), an internal criteria used to determine a final assay result, was selected as an additional means of assay reproducibility. Overall mean SDPA values with variance components (SD and %CV) are shown in Tables 6 and 7.

	SITE							SDPA Values1
Category	Site 1PercentAgreement		Site 2PercentAgreement		Site 3PercentAgreement		Overall PercentAgreement	OverallMean	SD	%CV
Neg1	30/30	100.0%	30/30	100.0%	30/30	100.0%	100.0% (95% CI: 95.9%, 100.0%)	28.7	0.30	1.1
HN1:1001,2	28/30	93.3%	25/30	83.3%	30/30	100.0%	92.2% (95% CI: 84.8%, 96.2%)	28.8	0.39	1.4
HN1:101,2	17/30	56.7%	8/30	26.7%	20/30	66.7%	50.0% (95% CI: 39.9%, 60.1%)	28.8	0.35	1.2
LP	30/30	100.0%	30/30	100.0%	30/30	100.0%	100.0% (95% CI: 95.9%, 100.0%)	32.5	0.77	2.4
MP	30/30	100.0%	30/30	100.0%	30/30	100.0%	100.0% (95% CI: 95.9%, 100.0%)	31.6	0.82	2.6

Table 6: Site-To-Site Reproducibility Study Results using One Lot of the BD MAX™ Cdiff Assay
----------------------------------------------------------------------------------------------

For the Negative and High Negalive, SDPA values reported are for the SPC. For other reported are for the toxigent C. difficile target.

2 For the High Negative calegones, the expective. Therefore, Therefore, percent agreement was calculated for negative results.

Table 7: Lot-to-Lot Reproducibility Study Results using Three Lots of the BD MAX™ Cdiff Assay

	LOT							SDPA Values¹
Category	Lot 1PercentAgreement		Lot 2PercentAgreement		Lot 3PercentAgreement		Overall PercentAgreement		OverallMean	SD	%CV
Neg¹	30/30	100.0%	30/30	100.0%	30/30	100.0%	100.0%	(95% CI: 95.9%, 100.0%)	29.0	0.57	2.0
HN1:1001,2	29/30	96.7%	28/30	93.3%	30/30	100.0%	96.7%	(95% CI: 90.7%, 98.9%)	29.0	0.57	2.0
HN1:101,2	17/30	56.7%	21/30	70.0%	20/30	66.7%	64.4%	(95% CI: 54.2%, 73.6%)	29.0	0.58	2.0
LP	30/30	100.0%	30/30	100.0%	30/30	100.0%	100.0%	(95% CI: 95.9%, 100.0%)	32.8	0.78	2.4
MP	30/30	100.0%	30/30	100.0%	30/30	100.0%	100.0%	(95% CI: 95.9%, 100.0%)	32.1	0.80	2.5

For the Negative and High Negative satesories SDPA values reported are for the SPC. For other reported are for the baile in Coricenic C. difficile target.

2 For the High Negative categories, the expective. Therefore. Therefore, percent arreement was calculated for negative results

Sample Storage

Collected specimens can be stored at 2-25°C for a maximum of 48 hours or at 2-8°C for a maximum of 120 hours (5 days) before testing. In case of repeat testing from the Sample Buffer Tube, the following storage conditions apply:

up to 5h after the end of the initial run when stored at 25 ± 2℃ or .
. up to 120h after the end of the initial run when stored at 2-8°C.

Controls

External Control materials are not provided by BD. Various types of External Controls are recommended to allow the user to select the most appropriate for their laboratory quality control program:

Commercially available control materials (e.g., ATCC® 43255, a C. difficile strain . bearing the tcdB gene, and ATCC® 700057, a non-toxigenic C. difficile strain, can be used as positive and negative controls, respectively);
Suspensions of bacterial strains characterized by the user as toxigenic or non-toxigenic; .

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Previously characterized clinical specimens known to be positive or negative for . toxigenic C. difficile.
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.

Analytical Sensitivity

The analytical sensitivity (Limit of Detection or LoD) for the BD MAX™ Cdiff Assay was determined as follows: individual inoculating loops were dipped into C. difficile bacterial suspensions at different concentrations, prepared and quantified from cultures of four C. difficile strains representing three toxinotypes (0, III, VIII). Nine bacterial concentrations ranging between 0 and 64,000 CFU/mL were tested for each toxinotype. Each loop was then transferred to a SBT, already containing fecal matrix negative for toxigenic C. difficile. Each C. difficile strain was tested in replicates of 24 per concentration, by two different operators, using three different production lots of the BD MAXTM Cdiff Assay. The results were analyzed using a statistical linear logistic model. Briefly, the method models the positive response (expressed in percentage) as a function of Log (CFU/mL). The logistic model equation for the fitted curve allows the computation of the LoD by inverse prediction using the parameter estimates and their 95% confidence interval. The LoD was defined as the lowest concentration at which 95% of all replicates tested positive. The LoD ranged from 125 to 265 CFU per loop for each strain (Table 8).

C. difficile Strain	Toxinotype	LoD in CFU per loop
ATCC® 43255	0	265 (95% CI: 140, 502)
ATCC® 9689	0	156 (95% CI: 82, 298)
ATCC® BAA-1805	III	205 (95% CI: 102, 412)
ATCC® 43598	VIII	125 (95% CI: 66, 235)

Table 8: Limit of Detection of the BD MAX™ Cdiff Assay

Analytical Inclusivity

A variety of toxigenic C. difficile strains were included in this study taking into account geographic origin, toxinotype, NAP1 outbreaks and temporal diversity. Sixty-four (64) strains including 23 toxinotypes and representing 21 countries were tested, including strains from public collections and well-characterized clinical isolates (see Table 9). The assay correctly identified 62 of the 64 toxigenic C. difficile strains which were tested at ~3xLoD. Two (2) strains produced low signal results and were false-negative in one out of five replicates.

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Strain ID	Toxinotype	Strain ID	Toxinotype	Strain ID	Toxinotype
ATCC 700792 (14797-2)		DII1		M30761	VI
ATCC 17858 (1253)		QI1		57267	VII
ATCC 51695 (BDMS 18AN)		MI23	ND1	ATCC 43598	VIII
ATCC 43600 (2149)		Ell1		51680	IX
ATCC 43599 (2022)		PI2		M46722	IX
ATCC 43596 (545)		M14614	0	M40767	IX
ATCC 43594 (W1194)		M39177	0	8864	X
ATCC 17857 (870)		ATCC 43255	0	M26479	XII
ATCC BAA-1382 (630)		ATCC 9689	0	IS25	XII2
141		M16256	I	R9367	XIII
CD11	ND1	AC008	II	R10870	XIV
301		M14473	III	R9385	XV2
CD 246		M28681	III	SUC36	XVI
NCTC 11382		M37992	III	J9965	XVII
NCTC 11204		M41124	III	K095	XVIII
NI1		M1137	III	TR13	XIX
C13		ATCC BAA-1805	III	CH6223	XXI
F19		SE844	IIIa	M13883	XXI
L16		55767	IV	8785	XXIII
K13		M25097	IV	597B	XXIV
GII1		SE881	V
HI1		51377	VI

Table 9: Strains Tested in the Inclusivity Study of the BD MAX™ Cdiff Assay.

1 ND = Not Determined.

2 The repeat result is presented here. The initial result was negative. Positive results were obtained upon retest from SBT and in an additional test performed with 3 replicates. Overall, 4/5 test results were found positive.

Analytical Specificity

The BD MAX™ Cdiff Assay was performed on samples containing phylogenetically related species (Clostridium other than toxigenic C. difficile) and other organisms (bacteria, viruses) likely to be found in stool specimens (Table 10).

Six (6) out of six C. difficile strains not bearing the tcdB gene, tested at a . concentration ≥ 1 X 10° CFU/mL, produced negative results with the BD MAX™ Cdiff Assay;
. Thirty (30) out of 30 Clostridium strains other than C. difficile, including four strains of C. sordelli, tested at a concentration ≥ 1 X 10° CFU/mL, produced negative results with the BD MAX™ Cdiff Assay;
. Ninety-five (95) out of 98 other bacterial strains, including 93 species and subspecies, were tested at a concentration ≥ 1 X 108 CFU/mL (or ~ 1 X 108 genomic DNA cp/mL or 1 X 10° elementary bodies/mL) and produced negative results with the BD MAX " Cdiff Assay. The following strains gave a positive result:
- . Bacteroides stercoris (ATCC 43183)
- Gemella morbillorum (ATCC 27824) .

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Peptoniphilus asaccharolyticus (ATCC 14963)

An investigation was conducted and determined that the false-positive results were due to contamination. Overall, out of 5 replicates, the three strains each gave an initial positive result due to contamination. ATCC 27824 gave negative results for the 4 other replicates. However, ATCC 43183 and ATCC 27824 gave another positive result due to instrument issue and the 3 last replicates were found negative.

Seven (7) out of seven viruses, tested at a concentration ≥ 1 X 10° PFU/mL, produced negative results with the BD MAX" Cdiff Assay.

Table 10: Species Tested for the Cross-Reactivity Study
Clostridium species (≥ 1x10° CFU/mL)
Clostridium beijerinckii	Clostridium histolyticum	Clostridium septicum
Clostridium bifermentans	Clostridium innocuum	Clostridium sordellii
Clostridium bolteae	Clostridium nexile	Clostridium lavalense
Clostridium butyricum	Clostridium novyi	Clostridium sphenoides
Clostridium chauvoei	Clostridium orbiscindens	Clostridium spiroforme
Clostridium difficile(non-toxigenic strains)	Clostridium paraputrificum	Clostridium sporogenes
Clostridium difficile(Xla (A-B-tox bin+) and XIb)	Clostridium perfringens	Clostridium symbiosum
Clostridium fallax	Clostridium ramosum	Clostridium tertium
Clostridium haemolyticum	Clostridium scindens	Clostridium tetani
Other Bacterial Species (≥ 1x108 CFU/mL)
Abiotrophia defectiva	Enterococcus faecium VanA	Plesiomonas shigelloides
Acinetobacter baumannii	Enterococcus gallinarum	Porphyromonasasaccharolytica
Acinetobacter Iwoffii	Enterococcus hirae	Prevotella melaninogenica
Aeromonas hydrophila	Enterococcus raffinosus	Proteus mirabilis
Alcaligenes faecalis subsp.faecalis	Escherichia coli	Proteus penneri
Anaerococcus tetradius	Escherichia fergusonii	Providencia alcalifaciens
Bacillus cereus	Escherichia hermannii	Providencia rettgeri
Bacteroides caccae	Fusobacterium varium	Providencia stuartii
Bacteroides stercoris	Gardnerella vaginalis	Pseudomonas aeruginosa
Bifidobacterium adolescentis	Gemella morbillorum	Pseudomonas putida
Bifidobacterium longum	Hafnia alvei	Ruminococcus bromii
Campylobacter coli	Helicobacter cinaedi	Salmonella enterica subsp.enterica
Campylobacter jejuni subsp.jejuni	Helicobacter pylori	Salmonella enterica subsp.arizonae
Candida albicans	Klebsiella oxytoca	Serratia liquefaciens
Candida catenulata	Klebsiella oxytoca	Serratia marcescens
Cedecea davisae	Klebsiella pneumoniae subsp.pneumoniae	Shigella boydii
Citrobacter amalonaticus	Lactobacillus acidophilus	Shigella dysenteriae
Citrobacter freundii	Lactobacillus reuteri	Shigella sonnei
Citrobacter koseri	Lactococcus lactis subsp. lactis	Staphylococcus aureussubsp. aureus
Citrobacter sedlakii	Leminorella grimontii	Staphylococcus epidermidis
Collinsella aerofaciens	Listeria grayi	Stenotrophomonas

Table 10: Species Tested for the Cross-Reactivity Study

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Corynebacterium genitalium	Listeria innocua	Streptococcus agalactiae
Desulfovibrio piger	Listeria monocytogenes	Streptococcus dysgalactiaesubsp. dysgalactiae
Edwardsiella tarda	Mitsuokella multacida	Streptococcus intermedius
Eggerthella lenta	Mobiluncus curtisii subsp.holmesii	Streptococcus uberis
Enterobacter aerogenes	Moellerella wisconsensis	Trabulsiella guamensis
Enterobacter cloacae subsp.cloacae	Morganella morganii subsp.morganii	Veillonella parvula
Enterococcus casseliflavus	Neisseria gonorrhoeae	Vibrio parahaemolyticus
Enterococcus cecorum	Parabacteroides merdae	Yersinia bercovieri
Enterococcus dispar	Peptoniphilus asaccharolyticus	Yersinia rohdei
Enterococcus faecalis	Peptostreptococcus anaerobius
Intracellular bacteria(1x108 elementary bodies/mL)	Vibrio cholerae species(~1x108 cp/mL)	Human sample(~1x109 cp/mL)
Chlamydia trachomatis	Vibrio cholerae	Homo sapiens
virus (≥ 1x106 PFU/mL)
Adenovirus Type 14	Enterovirus	Cytomegalovirus, Strain AD-169
Rotavirus, stain WA	Echovirus 19 (Strain Burke)
Norovirus group 1	Coxsackie virus B1 (Com-5)

Interfering Substances

Twenty-five (25) biological and chemical substances occasionally used or found in perianal, rectal and/or stool specimens were evaluated for potential interference with the BD MAX™ Cdiff Assay. Two (2) organisms (E. coli ATCC 25922 and non-toxigenic C. difficile ATCC 700057) were also tested at high loads in order to assess bacterial interference. Toxigenic C. difficile negative specimens and toxigenic C. difficile positive specimens at 2-3X LoD were tested with the highest amount of each compound likely to be found in the specimens or with interfering organisms (1 X 10° CFU/mL of each strain). Potentially interfering substances include calcium carbonate (Tums®) as well as magnesium and aluminum hydroxide (Maalox® liquid). Results demonstrated no reportable interference with any other tested substance except for Mesalamine rectal suspension enema and Gynol II® that both showed slight inhibition (delay of Second Derivative Peak Abscissa) in the BD MAX™ Cdiff Assay. however, expected assay results were still obtained (Table 11).

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Brand Name or Description	Weight orVolumeTested/SBT	Result	Brand Name or Description	Weight orVolumeTested/SBT	Result
Nystatin	10 µL	NI	Pepto Bismol™	10 µL	NI
Hyderm™ Hydrocortisone(cream)	0.0246 g	NI	Ex-Lax®	0.0134 g	NI
Glycerin Suppositories	0.0129 g	NI	Metronidazole	10 µL	NI
Ihle's Paste	0.0388 g	NI	Vancomycin	10 µL	NI
Anusol® Plus	0.0123 g	NI	Polysporin®	0.0240 g	NI
Preparation H® with Bio-Dyne® (cream)	0.0222 g	NI	Naproxen	10 µL	NI
Major Prep® withPhenylephrine	0.0111 g	NI	Tucks® PersonalCleansing Pads	3 mm²	NI
Tums®	0.0395 g	I	Triglyceride Mix (C2-C10)	10 µL	NI
Maalox® (liquid)	10 µL	I	Palmitic Acid	25 mg	NI
Mesalamine RectalSuspension Enema	10 µL	*	Stearic Acid	10 mg	NI
Fleet® Mineral Oil Enema	0.0182 g	NI	Blood	10 µL	NI
Gynol II® VaginalContraceptive(with Nonoxynol-9)	0.0262 g	*	Mucus	10 µL	NI
Imodium AD®	0.0062 g	NI	E. coli + non-toxigenicC. difficile	10 µL	NI

Table 11: Endogenous and Commercial Exogenous Substances tested with the BD MAX™ Caiff Assay

I: Interference with the BD MAX™ Cdiff Assay.

NI: No reportable interference with the BD Cdiff™ Assay.

Mesalamine rectal suspension enema and Gynol II® (with nonoxynol-9) showed slight inhibition (delay of Second Derivative Peak Abscissa) in the BD MAX™ Cdiff Assay, however, expected assay results were still obtained.

Carryover / Cross-Contamination

A study was conducted to investigate within-run carryover and between-run carryover while processing specimens with high bacterial load of toxigenic C. difficile in the BD MAX™ Cdiff assay. A panel made of one high positive member and one negative member was used to prepare numerous samples. A Clostridium difficile strain (Tox 0, ATCC 9689) was used for the high positive C. difficile panel member (~3x108 CFU/mL). The negative member did not contain any target analyte. Twelve (12) replicates of the high positive panel member and 12 replicates of the negative panel member were tested in each run by alternating negative and positive samples. Three (3) operators performed 3 consecutive runs for a total of 9 runs of 24 samples. There were no false positive results due to carryover contamination.

Clinical Performance Studies

Clinical performance characteristics of the BD MAX™ Cdiff Assay were determined in a multi-site prospective investigational study. Six (6) investigational centers participated in the study. To be enrolled in the study, specimens had to be from patients suspected of having C. difficile infection for which diagnostic tests were indicated and ordered. Only soft or liguid stools, and only one specimen per patient, were included.

The Comparative Reference Method consisted of direct culture complemented by enriched culture. Enriched culture analysis was completed for all specimens that were negative for

{16}------------------------------------------------

toxigenic C. difficile by direct culture. The anaerobic culture was used to isolate C. difficile, if present. This was followed by confirmation of the isolate identification and a Tissue Culture Cytotoxicity Assay to determine the toxigenicity of the isolate.

Of the 2071 soft or liguid stool specimens compliant with the Reference Method (Direct and Enriched Culture). 1819 gave compliant and reportable results with the BD MAX ™Cdiff Assay. In comparison to the Reference Method, the BD MAX™ Cdiff Assay identified 87.7% of the toxigenic C. difficile positive specimens and 96.8% of the toxigenic C. difficile negative specimens (Tables 12 and 13).

Table 12: Results Obtained with the BD MAX™ Cdiff Assay in Comparison to the Reference Method

All Sites	Reference Method
	+	-	Total
BD MAX TM CdiffAssay	265	481	313
	371	1469	1506
Total	302	1517	1819
Sensitivity: 87.7% (265/302) (95% CI: 83.6%, 91.0%)Specificity: 96.8% (1469/1517) (95% CI: 95.8%, 97.6%)PPV: 83.5% (95% CI: 79.4%, 87.1%)NPV: 97.7% (95% CI: 97.0%, 98.4%)

1 Further investigation was performed on specimens with discordant results between the Reference Method and the BD MAX™ Cdiff Assay.

27 of 48 False Positive BD MAX™ Cdiff specimens were also found to be positive using another . commercially available FDA-cleared RT-PCR assay targeting the C. difficile todB gene.

32 of 37 False Negative BD MAX™ Cdiff specimens, were also found to be negative using another . commercially available FDA-cleared RT-PCR assay targeting the C. difficile tcdB gene.

	Table 13. Results Obtained by Site using the BD MAX™ Cdiff Assay in Comparison to the
		Reference Method

Site	Sensitivity	Specificity
Site 1	90.0% (18/20)(69.9%, 97.2%)1	95.3% (202/212)(91.5%, 97.4%)
Site 2	84.4% (38/45)(71.2%, 92.3%)	95.3% (205/215)(91.7%, 97.5%)
Site 3	94.7% (36/38)(82.7%, 98.5%)	97.9% (275/281)(95.4%, 99%)
Site 4	83.8% (31/37)(68.9%, 92.3%)	95.8% (322/336)(93.1%, 97.5%)
Site 5	96.1% (49/51)(86.8%, 98.9%)	98.4% (186/189)(95.4%, 99.5%)
Site 6	83.8% (93/111)(75.8%, 89.5%)	98.2% (279/284)(95.9%, 99.2%)
Overall Study	87.7% (265/302)(83.6%, 91.0%)	96.8% (1469/1517)(95.8%, 97.6%)

Numbers in parentheses express the 95% confidence interval boundaries

{17}------------------------------------------------

In comparison to direct culture, the BD MAX™ Cdiff Assay identified 96.5% of the toxigenic C. difficile positive specimens and 92.7% of the toxigenic C. difficile negative specimens (Tables 14 and 15).

All Sites		Direct Culture
		+	-	Total
BD MAX TM CdiffAssay	+	194	118	312
	-	7	1507	1514
Total		201	1625	1826
Positive Percent Agreement: 96.5% (194/201) (95% CI: 93.0%, 98.3%)

Table 14: Results Obtained with the BD MAX™ Cdiff Assay in Comparison to Direct Culture

Table 15. Results Obtained by Site using the BD MAX™ Cdiff Assay in Comparison to Direct Culture

Site	SensitivityPositivePercent Agreement	Negative PercentAgreement
Site 1	92.9% (13/14)(68.5%, 98.7%) 1	93.1% (203/218)(89.0%, 95.8%)
Site 2	100.0% (26/26)(87.1%, 100%)	90.6% (213/235)(86.2%. 93.7%)
Site 3	96.0% (24/25)(80.5%. 99.3%)	93.9% (276/294)(90.5%. 96.1%)
Site 4	93.8% (15/16)(71.7%, 98.9%)	91.7% (330/360)(88.4%. 94.1%)
Site 5	95.7% (45/47)(85.8%, 98.8%)	96.4% (188/195)(92,8%. 98.3%)
Site 6	97.3% (71/73)(90.5%. 99.2%)	92.0% (297/323)(88.5%. 94.4%)
Overall Study	96.5% (194/201)(93.0%, 98.3%)	92.7% (1507/1625)(91.4%, 93.9%)

1 Numbers in parentheses express the 95% confidence interval boundaries

Out of 1860 soft or liquid stool specimens tested with the BD MAX™ Cdiff Assay, 58 (3.1%) were initially reported as unresolved. 42 of those were repeated and 32 were resolved upon repeat testing. Overall, 0.5% remained unresolved after repeat (Table 16).

Initial Unresolved Rate	Unresolved Rate After Repeat
3.1% (58/1860)* (95% CI: 2.4%, 4.0%)	0.5% (10/1844) (95% CI: 0.3%, 1.0%)

Table 16: Unresolved Rate
-------------------------------

{18}------------------------------------------------

Total number based on compliant specimens and BD MAX™ Cdiff Assay results.

Out of 1916 soft or liquid stool specimens tested with the BD MAX™ Cdiff Assay, 21 (1.1%) were initially reported as indeterminate. Out of a total of 1844 compliant results, no result remained Indeterminate upon repeat (considering valid results and compliant repeats).

Out of 1916 soft or liquid stool specimens tested with the BD MAX™ Cdiff Assay, 28 (1.5%) were initially reported as incomplete. Out of a total of 1844 compliant results, no result remained Incomplete upon valid repeat (considering valid results and compliant repeats).

Comparison Studies

In addition to the multi-site investigational study, a comparison study was performed using the BD MAX™ Cdiff assay and two (2) commercially available FDA-cleared molecular assays for the detection of the C. difficile tcdB gene. Testing was performed on 2013 specimens at two external sites.

In comparison to one FDA-cleared molecular test (Table 10a), the PPA and NPA of the BD MAX™ Cdiff Assay were 99.1% (Cl: 94.9%-99.8%) and 97.4% (Cl: 95.7%-98.4%). respectively.

In comparison to a second FDA-cleared molecular test (Table 10b), the PPA and NPA of the BD MAX™ Cdiff Assay were 95.5% (Cl: 92.1%-97.5%) and 98.8% (Cl: 97.9%-99.3%), respectively.

All Sites		FDA-cleared Molecular Assay 1
		+	-	Total
BD MAX TM CdiffAssay	+	106	14	120
	-	1	526	527
	Total	107	540	647

Table 17a: Results Obtained with the BD MAX™ Cdiff Assay in Comparison to a Commercially Available FDA-cleared Molecular Assay for C. difficile.

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	FDA-cleared Molecular Assay 2
All Sites	+	-	Total
BD MAXTM CdiffAssay +	233	14	247
BD MAXTM CdiffAssay -	11	1108	1119
Total	244	1122	1366

Table 17b: Results Obtained with the BD MAX™ Cdiff Assay in Comparison to a second Commercially Available FDA-cleared Molecular Assay for C. difficile.

Expected Values

In the BD MAX™ Cdiff Assay clinical study a total of 1834 reportable results, from specimens compliant at the specimen and PCR levels, were obtained from 6 geographically diverse sites and compared with Direct and Enriched culture. The study population was grouped into in-patient, out-patient and unknown categories. The number and percentage of positive cases, as determined by the BD MAX™ Cdiff Assay, are presented in Table 18 below.

Group	Total Number ofSpecimens	BD MAX™ Cdiff AssayNumber Positive	NumberNegative	Positive Percentage
In-patient	1249	184	1065	14.7% (184/1249)
Out-patient	457	114	343	24.9% (114/457)
Unknown	128	17	111	13.3% (17/128)
Total1	1834	315	1519	17.2% (315/1834)

Table 18: Expected Values

1Total number of specimens based on compliant PCR results

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DEPARTMENT OF HEALTH & HUMAN SERVICES

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Public Health Service

Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002

PATRICIA DIONNE DIRECTOR, REGULATORY AFFAIRS GENEOHM SCIENCES CANADA, INC. (BD DIAGNOSTICS) 2555 BOUL. DU PARC-TECHNOLOGIQUE QUEBEC (QUEBEC) G1P 4S5 CANADA

April 2, 2013

Re: K130470

Trade/Device Name: Bd MAX Cdiff Assay Regulation Number: 21 CFR 866.3130 Regulation Name: Clostridium difficile Toxin Gene Amplification Assay Regulatory Class: II Product Code: OZN, OOI Dated: February 22, 2013 Received: February 27, 2013

Dear Dr. Dionne:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food. Drug. and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration. Iisting of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Parts 801 and 809); medical device reporting (reporting of medical device-related adverse events) (21 CFR 803); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

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If you desire specific advice for your device on our labeling regulations (21 CFR Parts 801 and 809), please contact the Office of In Vitro Diagnostics and Radiological Health at (301) 796-5450. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to

http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/default.htm for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.

You may obtain other general information on your responsibilities under the Act from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address http://www.fda.gov/MedicalDevices/Resourcesfor You/Industrv/default.htm.

Sincerely yours,

Uwe Scherf -S for

Sally A. Hojvat, M.Sc., Ph.D. Director Division of Microbiology Devices Office of In Vitro Diagnostics and Radiological Health Center for Devices and Radiological Health

Enclosure

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1.2 Indications for Use Statement

510(k) Number (if known): K_130470

Device Name: _________________________________________________________________________________________________________________________________________________________________

Intended Use:

The BD MAX™ Cdiff Assay performed on the BD MAX™ System is an automated in vitro diagnostic test for the direct, qualitative detection of the Clostridium difficile toxin B gene (tcdB) in human liquid or soft stool speciments from patients suspected of having C. difficile infection (CDI). The test, performed directly on the speciment utilizes real-time polymerase chain reaction (PCR) for the amplification of C. difficile toxin B gene DNA and fluorogenic target-specific hybridization probes for the detection of the amplified DNA. The BD MAX™ Cdiff Assay is intended to aid in the decedion of Clif

Prescription

Use	XXX
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(Per 21 CFR 801.109)Over-The-Counter Use

(Optional Format 1-2-96)

(PLEASE DO NOT WRITE BELOW THIS LINE - CONTINUE ON ANOTHER PAGE IF NEEDED)

Concurrence of CDRH, Office of In Vitro Diagnostic Devices Evaluation and Safety (OIVD)

Raquel A. Peat-S
2013.04.02 12:52:34 -04'00'

Division Sign-Off Office of In Vitro Diagnostics and Radiological Health 510 (k) K130470

Regulation Number and Section

§ 866.3130 Clostridium difficile toxin gene amplification assay.

(a)
Identification. AClostridium difficile toxin gene amplification assay is a device that consists of reagents for the amplification and detection of target sequences inClostridium difficile toxin genes in fecal specimens from patients suspected of havingClostridium difficile infection (CDI). The detection of clostridial toxin genes, in conjunction with other laboratory tests, aids in the clinical laboratory diagnosis of CDI caused byClostridium difficile. (b)
Classification. Class II (special controls). The special controls are set forth in FDA's guideline document entitled: “Class II Special Controls Guideline: Toxin Gene Amplification Assays for the Detection ofClostridium difficile; Guideline for Industry and Food and Drug Administration Staff.” See § 866.1(e) for information on obtaining this document.