Strep B Carrot Broth™ One-Step is a selective and differential medium which is intended for the detection of Group B Streptococcus (GBS) from anovaginal specimen collected from pregnant women. The medium is used as an aid in the qualitative determination of GBS colonization in pregnant women. The color change reaction from white to orange is representative of a positive result for presence of GBS. The medium requires 24 hours of incubation but positive results can be interpreted as early as 16 hours. Due to the properties of Strep B Carrot Broth™ One-Step, non-hemolytic GBS cannot be detected by the medium's color change and require subculture for identification. Any presumptive negative indicated by lack of color change at the incubation period must be subcultured to a non-selective medium (e.g. Tryptic Soy Agar with 5% Sheep Blood) to confirm absence of GBS. Subculture must also be performed to recover isolates for conducting susceptibility testing as recommended for penicillin-allergic women.

Device Description

Strep B Carrot Broth™ One-Step is a selective and differential medium with selective components designed to enrich for Group B Streptococci. The production of a light orange, or red-orange pigment is a unique characteristic of hemolytic GBS due to reaction with substrates such as starch, peptone, serum, and folate pathway inhibitors. GBS detection with Strep B Carrot Broth™ One-Step is only possible with β-hemolytic Group B Streptococci colonies, providing evidence of a direct genetic linkage between pigment production in this media and hemolysin production. Non-hemolytic GBS can be recovered from Strep B Carrot Broth™ One-Step upon subculture to 5% sheep blood agar plates.

AI/ML Overview

The provided text describes the performance evaluation of the "Strep B Carrot Broth™ One-Step" device. Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" in a separate section with numerical targets. However, the performance data presented (sensitivity and specificity) is implicitly the criteria the device met for substantial equivalence. The predicate device's performance is not provided in numerical values, but the comparison is implied through the overall "Substantially Equivalent?" column.

Metric	Acceptance Criteria (Implied by the study results in comparison to routine culture)	Reported Device Performance (vs. LIM Reference Method + Subculture of Presumptive Negatives)
Sensitivity	High sensitivity to detect GBS	98.8% (95% CI: 95.6-99.7)
Specificity	High specificity to correctly identify GBS and rule out other organisms	98.2% (95% CI: 96.8-99.0)
Recovery Rate	Able to recover GBS at low concentrations	10^3 CFU/mL (30 CFU/tube) for β-hemolytic GBS strains
Analytical Reactivity	Consistent detection across various GBS serotypes without color change for non-hemolytic strains	100% of tested β-hemolytic GBS strains produced orange color. Non-hemolytic strains recovered by subculture.
Analytical Specificity	No false positive color reactions with common non-target organisms	All 78 non-target organisms produced negative color reactions; 57.7% recoverable on subculture.
Microbial Interference	Target organisms should be recoverable in the presence of high concentrations of non-target organisms	Expected color reaction with target organisms in presence of high concentrations (1.5 x 10^6 CFU/mL) of all but one non-target organism; E. faecalis required lower concentration (10^5 CFU/mL for hemolytic GBS, 10^6 CFU/mL for non-hemolytic GBS recovery by subculture).
Interfering Substances	No interference from common endogenous/exogenous substances	No interference observed from 16 tested substances at highest clinically relevant concentrations.
Incubation Study	Performance maintained within specified incubation range	Incubation range of 16-24 hours established; all hemolytic GBS produced color by 20 hours, all GBS recovered by subculture at 12 hours.
Specimen Stability	Maintained performance across various transport media and storage conditions	100% GBS recovery and color change from Healthlink swabs at 2-8°C for up to 96 hours, and TransPRO™ Liquid Amies at 2-8°C for up to 120 hours.
Reproducibility	Consistent results across different sites and operators	>95% agreement with known test results across three sites on five work days.

2. Sample Size Used for the Test Set and Data Provenance

Test Set Sample Size: A total of 884 specimens were initially collected, but 113 were excluded, resulting in 771 valid samples for the primary comparison.
- Data Provenance: The study was conducted at four geographically diverse hospitals with routine GBS specimens (anovaginal swabs). This indicates a prospective collection within normal clinical practice. The country of origin is not explicitly stated but implied to be the US given the FDA submission.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications

The document does not explicitly state the number of experts or their specific qualifications (e.g., "radiologist with 10 years of experience") for establishing ground truth.
Ground Truth Establishment: For the primary comparison, the reference method was "routine culture," defined as:
- Selective enrichment in LIM Broth.
- Followed by subculture to Blood Agar.
- Confirmed by biochemical testing.
- Organisms grown on Blood Agar were confirmed using gram-stain, catalase test, and latex agglutination.
- Discrepant isolates underwent re-testing and confirmation at Hardy Diagnostics using a "discrepant analysis protocol." This re-testing included confirming identity (β-hemolytic GBS, non-hemolytic GBS, or non-GBS) and testing at the Limit of Detection (LoD).

4. Adjudication Method for the Test Set

The document implies a form of adjudication for discrepant results. All discrepant isolates (false positives and false negatives) were re-tested and confirmed at Hardy Diagnostics using a specific "discrepant analysis protocol." This suggests a process where initial disagreements between the test device and the reference method were further investigated to establish the definitive ground truth. It is not explicitly described as a 2+1 or 3+1 method; rather, it appears to be a single "expert site" (Hardy Diagnostics) reviewing discrepancies.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No, an MRMC comparative effectiveness study was not explicitly done as described. The study evaluates a culture medium, not an imaging AI diagnostic device. The "reproducibility" section mentions "at least one operator and two readers, blinded to each other's results, per site" for the reproducibility panel of 12 isolates, but this is to demonstrate proficiency and reproducibility of the device itself, not to compare human reader performance with and without AI assistance on a large test set. Therefore, no effect size of human readers improving with AI vs. without AI assistance is reported.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done

Yes, a standalone performance was done for the "Strep B Carrot Broth™ One-Step" in its primary mode of operation. The device is a culture medium designed to produce a visual color change. The performance metrics (sensitivity and specificity in Table 1) directly reflect the device's ability to produce this color change as a standalone indicator of GBS presence, compared to the reference method. The subsequent subculture for negatives or non-hemolytic GBS is part of the overall diagnostic workflow, but the initial "color reaction" is a standalone readout.

7. The Type of Ground Truth Used

The ground truth used was expert consensus informed by a reference culture method (LIM Broth + subculture to Blood Agar) and confirmed by biochemical testing, gram-stain, catalase test, and latex agglutination. For discrepant cases, further re-testing and confirmation at a central lab (Hardy Diagnostics) was performed. This is a form of laboratory reference standard.

8. The Sample Size for the Training Set

The document does not mention a training set sample size. This is common for traditional culture media, which are developed based on established microbiological principles and validated rather than "trained" in the machine learning sense. The performance data presented is for validation.

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

As there is no explicit mention of a training set, the method for establishing ground truth for a training set is not applicable or provided.

Summary

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Image /page/0/Picture/1 description: The image is a black and white logo for the U.S. Department of Health & Human Services. The logo consists of a circular border with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" written around it. Inside the circle is a stylized image of three human profiles facing to the right, with a design that resembles a caduceus or a flowing ribbon.

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

May 22, 2017

HARDY DIAGNOSTICS CHRISTOPHER MASSEY DIRECTOR OF RESEARCH & DEVELOPMENT 1430 WEST MCCOY LANE SANTA MARIA CA 93455

Re: K170586

Trade/Device Name: Strep B Carrot Broth One-Step Regulation Number: 21 CFR 866.2360 Regulation Name: Selective culture medium Regulatory Class: II Product Code: POZ Dated: January 20, 2017 Received: February 28, 2017

Dear Mr. Massey:

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. listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

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 Division of Industry and Consumer Education at its toll-free number (800) 638 2041 or (301) 796-7100 or at its Internet address

http://www.fda.gov/MedicalDevices/Resourcesfor You/Industry/default.htm. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 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 Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address

http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm.

Sincerely yours,

Ribhi Shawar -S
For

Uwe Scherf, 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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Indications for Use

510/k) Number (if known) K170586

Device Name Strep B Carrot Broth™ One-Step

Indications for Use (Describe)

Type of Use (Select one or both, as applicable)

Prescription Use (Part 21 CFR 801 Subpart D)

Over-The-Counter Use (21 CFR 801 Subpart C)

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510(k) Summary - K170586

I. SUBMITTER

Chris Massey Director of Research & Development Hardy Diagnostics 1430 W. McCoy Lane Santa Maria, CA 93455 Phone: 805-346-2766 x 5620 E-mail: MasseyC@hardydiagnostics.com

II. DEVICE

Name of Device: Strep B Carrot Broth™ One-Step Classification Name: Selective Culture Medium Regulatory Class: I Product Code: PQZ

III. PREDICATE DEVICE

LIM Broth, K871447

IV. DEVICE DESCRIPTION

Approximately 10-35% of women are asymptomatic carriers of group B streptococci (GBS) in the genital and gastrointestinal tracts. Group B Streptococi (GBS) remains a leading cause of serious illness and death in newborn populations and, therefore, the detection of Group B Streptococci in the vaginal-anorectal area is critical to the prevention of neonatal GBS disease. The Centers for Disease Control and Prevention (CDC) recommends the screening of all pregnant women for vaginal and rectal Group B Streptococci colonization between 35 and 37 weeks of gestation using an enrichment broth followed by subculture.

V. INDICATIONS FOR USE

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Attribute	Device	Comparator	SubstantiallyEquivalent?
Name	Strep B Carrot Broth One-Step	LIM Broth	Yes
510(k) Details	510(k) number K170586Product Code PQZ21 CFR 866.2360"Culture media, selective and differential"Class IPanel 83 Microbiology	510(k) number K871447Product Code JSD21 CFR 866.2360"Culture Media, Selective Broth"Class IPanel 83 Microbiology	Yes
Intended Use	Strep B Carrot BrothTM One-Step is a selectiveand differential medium which is intended forthe detection of Group B Streptococcus (GBS)from anovaginal specimen collected frompregnant women. The medium is used as anaid in the qualitative determination of GBScolonization in pregnant women. The colorchange reaction from white to orange isrepresentative of a positive result for presenceof GBS. The medium requires 24 hours ofincubation but positive results can beinterpreted as early as 16 hours. Due to theproperties of Strep B Carrot BrothTM One-Step,non-hemolytic GBS cannot be detected by themedium's color change and require subculturefor identification. Any presumptive negativeindicated by lack of color change at the end ofthe incubation period must be subcultured toa non-selective medium (e.g. Tryptic Soy Agarwith 5% Sheep Blood) to confirm absence ofGBS. Subculture must also be performed torecover isolates for conducting susceptibilitytesting as recommended for penicillin-allergicwomen.	Remel Todd Hewitt Broth w/ CNA (LimBroth) is a liquid medium recommended foruse in qualitative procedures for theisolation of Group B Streptococcus (GBS)from clinical specimens containing mixedbacterial flora.	Yes
Methodology	Enrichment Broth, Chromogenic	Enrichment Broth	Yes
Inoculation	Direct	Direct	Yes
Sample Type	Vaginal/rectal swab	Vaginal/rectal swab	Yes
Interpretation	Manual/visual and subculture negatives	Manual/visual and subculture	Yes

VI. COMPARISON OF TECHNOLOGICAL CHARACTERISTICS WITH THE PREDICATE DEVICE

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VII. PERFORMANCE DATA

Performance of Strep B Carrot Broth™ One-Step was evaluated at four geographically diverse hospitals with routine GBS specimen in the form of an anovaginal swab. The detection of Group B Streptococi by orange color development in Strep B Carrot Broth™ One-Step was compared to routine culture, defined as the selective enrichment of specimen in LIM Broth, followed by subculture to Blood Agar and confirmed by biochemical testing. Additionally, the recovery of Group B Streptocci by a Strep B Carrot Broth™ One-Step subsequently subcultured to Blood Agar was also compared to LIM broth routine culture. Organisms that grew on Blood Agar were confirmed to be Group B Streptococci using gram-stain, catalase test, and latex agglutination.

A total of 884 specimens were tested against routine culture, 113 specimens did not meet enrollment criteria, and were therefore excluded from the analysis. Of the remaining 771 valid samples tested, a total of 143 specimens were confirmed positive for Group B Streptococci by orange color development in Strep B Carrot Broth™ One-Step after 24 hours of incubation at 35-37ºC with concordant results obtained from the LIM reference method. Those results are shown in Table 1.

All discrepant isolates were frozen in CryoSavers™ with Brucella Broth and returned to Hardy Diagnostics for testing. The identity of each isolate was confirmed (β Group B Streptococci, NH Group B Streptococci, or non-Group B Streptococci). Once the identity was confirmed, positive organisms (β Group B Streptococci or NH Group B Streptococi) were tested at LoD (10 CFU/mL) in donated negative-vaginal rectal matrix for their recovery from the LIM reference method, color development in Carrot Broth™ One-Step, and recovery from the Carrot Broth™ One-Step to Blood Agar System.

Site	TP	FP1	FN2	TN	Sensitivity	95% CI		Specificity	95% CI
CCP	47	1	4	141	92.2	81.5	96.9	99.3	96.1	99.9
NY	35	4	8	136	81.4	67.4	90.3	97.1	92.9	98.9
CC	26	0	2	83	92.9	77.4	98.0	100.0	95.6	100.0
MCW	35	3	6	240	85.4	71.6	93.1	98.8	96.4	99.6
Overall	143	8	20	600	87.7	81.8	91.9	98.7	97.4	99.3

Table 1. LIM Broth vs. Strep B Carrot Broth™ One-Step Color reaction

' There were 8 False Positives observed. All isolates were re-tested and confirmed at Hardy Diagnostics using the discrepant analysis protocol described above. Of these, six isolates were originally negative by LIM reference method, showed a positive color reaction in Strep B Carrot Broth™ One-Step, and were confirmed to be ß-hemolytic when subcultured on Blood Agar. One was not able to be confirmed because no GBS isolate was frozen and the remaining specimen had f-hemolytic colonies present on the blood agar plates; however, Proteus swarmed the technician from isolating the ß-hemolytic colonies for identification.

" There were 20 False Negatives observed. All isolates were re-tested and confirmed at Hardy Diagnostics using the discrepant analysis protocol described above. Fourteen of the B Group B Streptococci isolates recovered from LIM, but originally gave a negative Strep B Carrot Broth™ One-Step color reaction, were confirmed as B Group B Streptococci and subsequently confirmed to have a positive Strep B Carrot Broth™ One-Step color reaction at LoD. Two isolates were identified as very weak B Group B Streptococci and did not produce the expected color reaction in Strep B Carrot Broth™ One-Step. Four isolates were confirmed as non-hemolytic Group B Streptococi with a negative color reaction in Strep B Carrot Broth™ One-Step.

3 Considering that non-hemolytic GBS cannot be detected by the medium's color change and require subculture for identification, there were 5 specimens that were found to be non-hemolytic. Considering those results as true negatives, the overall Sensitivity and Specificity values observed when comparing the recovery of β-hemolytic GBS by the LIM reference method to the Strep B Carrot Broth™ One-Step color reaction were 90.4% (141/156) 195% CI: 84.7-94.1] and 98.4% (605/615) [95% CI: 97.0-99.1], respectively.

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When comparing the number of Group B Streptococci positive specimens recovered by the LIM reference method to the number identified by Strep B Carrot Broth™ One-Step color change in conjunction with the subculture of presumptive negatives to the Blood Agar, an additional 18 specimens showed concordant positive results for a total of 161 true positive results. The LIM reference method included the identification of both ß-hemolytic and non-hemolytic GBS from samples by culture. Those results are shown in Table 2.

Site	TP	FP1	FN2	TN	Sensitivity	95% CI	Specificity	95% CI
CCP	50	0	1	142	98.0	89.7	99.7	100.0	97.4	100.0
NY	43	6	0	134	100.0	91.8	100.0	95.7	91.0	98.0
CC	28	0	0	83	100.0	87.9	100.0	100.0	95.6	100.0
MCW	40	5	1	238	97.6	87.4	99.6	97.9	95.3	99.1
Overall	161	11	2	597	98.8	95.6	99.7	98.2	96.8	99.0

Table 2. LIM Reference Method vs. Strep B Carrot Broth™ One-Step (color), plus Subculture of Presumptive Negatives to Blood Agar with Biochemical Testing

There were eleven False Positives observed. All isolates were re-tested and confirmed at Hardy Diagnostics using the discrepant analysis protocol described above. All isolates recovered from the Strep B Carrot Broth to Blood Agar system were confirmed to be ß Group B Streptococci.

2 There were two False Negatives observed. Both isolates were re-tested and confirmed at Hardy Diagnostics using the discrepant analysis protocol described above. Both of the B Group B Streptococci isolates recovered from LIM were confirmed as B Group B Streptococci.

RECOVERY RATE

To determine the recovery [Limit of Detection (LoD)] of Strep B Carrot Broth™ One-Step, the media was challenged with two beta-hemolytic ATCC strains of Group B Streptococci at 10-fold decreasing concentrations and evaluated for color change. The lowest concentration at which a positive reaction was seen, indicated by an orange color, was determined to be the LoD. The determined by testing Strep B Carrot Broth™ One-Step with 20 replicate dilutions of the determined LoD concentrations. Strep B Carrot Broth™ One-Step was able to recover both S. agalactiae ATCC 12386 and S. aqalactiae ATCC 12403 at a LoD of 103 CFU/mL of the fluid from a flocked anovaginal swab specimen (30 CFU/tube when using a 30μL inoculum). Variable recovery was seen at lower concentrations. Blood agar plates were used to determine the concentrations of organisms present in each dilution.

ANALYTICAL REACTIVITY

Fifty-four ATCC reference and clinical Group B Streptococci strains representing seven of the nine known serotypes were recovered in Strep B Carrot Broth™ One-Step when inoculated at the limit of detection of 100 CFU/mL. The GBS serotypes included in this study were serotypes la, Ib, II, III, IV, V, and VI. Serotypes VII and VIII are rare and were not available for testing. Four strains that were non-typable against the nine known serotypes were also included. All the beta-hemolytic strains of Group B Streptococi produced the expected orange color in Strep B Carrot Broth™ One-Step. The non-hemolytic strains showed no orange color in Strep B Carrot Broth™ One-Step but were successfully recovered upon subculture to Blood Agar.

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ANALYTICAL SPECIFICITY

Seventy-eight non-target organisms that are phylogenetically-related to Group B Streptococci or potentially encountered in an anovaginal swab were tested in Strep B Carrot Broth™ One-Step at a concentration of 10° CFU/mL. All organisms tested are listed in Table 3 below. After 24 hours of incubation, all Carrot Broth tubes were evaluated for color reaction. In order to determine if Strep B Carrot Broth™ One-Step supported the growth of non-target organisms in the absence of a color reaction, all negative tubes were subcultured to an appropriate medium for the non-target organisms tested produced a negative color reaction in Strep B Carrot Broth™ One-Step and 45/78 (57.7%) of the organisms were recoverable when subcultured after enrichment.

Organism
Acinetobacter baumannii	Enterococcus durans	Proteus mirabilis
Aeromonas hydrophila	Enterococcus faecalis	Providencia alcalifaciens
Aspergillus brasiliensis	Enterococcus faecium	Pseudomonas aeruginosa
Bacillus cereus	Enterococcus flavescens	Pseudomonas fluorescens
Bacillus subtilis	Enterococcus hirae	Saccharomyces cerevisiae
Bacteroides fragilis	Enterococcus raffinosus	Salmonella enterica (typhii)
Bifidobacterium breve	Enterococcus saccharolyticus	Salmonella enterica arizonae
Campylobacter coli	Escherichia coli	Serratia marcescens
Campylobacter jejuni	Gardnerella vaginalis	Shigella boydii
Candida albicans	Geotrichum candidum	Shigella flexneri
Candida glabrata	Hafnia alvei	Shigella sonnei
Candida parapsilosis	Klebsiella oxytoca	Staphylococcus aureus
Candida tropicalis	Klebsiella pneumoniae	Staphylococcus epidermidis
Citrobacter brakkii	Lactobacillus acidophilus	Staphylococcus saprophyticus
Citrobacter freundii	Lactobacillus gasseri	Stenotroph. maltophilia
Citrobacter koseri	Lactobacillus leichmannii	Streptococcus mutans
Clostridium difficile	Lactococcus lactis	Streptococcus anginosus
Clostridium novyi	Legionella pneumophila	Streptococcus bovis
Clostridium perfringens	Listeria monocytogenes	Streptococcus dysgalactiae
Clostridium sporogenes	Micrococcus luteus	Streptococcus mitis
Corynebacterium jekeium	Moraxella catarrhalis	Streptococcus pneumoniae
Enterobacter aerogenes	Morganella morganii	Streptococcus pyogenes
Enterobacter cloacae	Neisseria gonorrhoeae	Streptococcus salivarius
Enterococcus casseliflavus	Pediococcus acidilacti	Streptococcus uberis
Enterococcus cecorum	Peptostreptococcus anaerobius	Vibrio parahaemolyticus
Enterococcus dispar	Plesiomonas shigelloides	Yersinia enterocolitica

Table 3. List of non-target organisms tested in Analytical Specificity

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MICROBIAL INTERFERENCE

Strep B Carrot Broth™ One-Step was challenged to determine if target organisms at low concentration could be recovered in the presence of non-target organisms at a high concentration. All organisms that were recovered upon subculture from Strep B Carrot Broth™ One-Step in the Analytical Specificity study were used in this Microbial Interference study. Non-target organisms at a high concentration (1.5 x 10° CFU/mL) were mixed with each target organism at the LoD concentration and inoculated into Strep B Carrot Broth™ One-Step. If the target organism was not recovered, the concentration of the non-target organism was lowered 10-fold until the target organism was recovered.

Strep B Carrot Broth™ One-Step was able to produce the expected color reaction with target organisms and allowed the recovery of both GBS strains in the presence of high concentrations (1.5 x 10 CFU/mL) of all but one of the non-target organisms used in this study. The only organism found to affect recovery was E. faecalis ATCC 29212. S. agalactiae ATCC 12386 produced the expected color reaction when the concentration of E. faecalis ATCC 29212 was 105 CFU/mL or lower. S. agalactiae ATCC 13813, a non-hemolytic strain, was recovered upon subculture when the concentration of E. faecalis ATCC 29212 was 10° CFU/mL or lower.

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INTERFERENCE

Commonly used or encountered endogenous and exogenous substances that may be present in anovaginal swabs were evaluated for potential interference of growth or chromogenic reaction in Strep B Carrot Broth™One-Step. The substances tested are listed in the table below. No interference was observed with any substance at the highest clinically relevant concentration in the GBS-negative specimen matrix.

Interfering Substances
Category	Substance/Supplier	Concentration inSample Matrix1
Anti-diarrhealMedication	Pepto-Bismol® (Bismuth subsalicylate solution)	1% v/v
	Imodium A-D® (Loperamide HCI)	2% w/v
Body Oil	Neutrogena Body Oil	2% v/v
Body Powder	Gold Bond Body Powder	1% w/v
Contraceptive Gel	Options Gynol II® (Nonoxynol-9)	0.59% w/v
Enema Solution	Physiological saline	0.25% v/v
Lubricating Gel	K-Y® Jelly	0.57% v/v
Oral Laxative	Milk of Magnesia	1.78% v/v
	Dulcolax® (Sodium picosulfate solution)	1% w/v
Polysorbate 80	Tween®80	10% v/v
Rectal Laxative	Fleet® Glycerin Suppositories	10% v/v
Topical HemorrhoidOintment	Preparation-H®	0.26% w/v
Vaginal Anti-ItchMedication	Vagisil® Cream	0.41% w/v
Vaginal Anti-FungalMedication	Monistat® (Miconazole nitrate)Lotrimin® (Clotrimazole)	0.29% w/v0.29% w/v
Endogenous Substances
Human Amniotic Fluid	Medfusion	2% v/v
Human Feces	Central Coast Pathology	2% v/v
Human Meconium	LEE Biosolutions	2% v/v
Human Urine	Central Coast Pathology	2% v/v
Human Whole Blood	In-house	2% v/v
Mucin	Sigma, M2378	0.05% w/v

Specific amounts of substance added to anovaginal specimen matrix calculated using GM=C>V=C>V> with the assumption that 1g=LmL.

INCUBATION STUDY

In order to determine a recommended incubation time range, the performance of Strep B Carrot Broth™ One-Step was evaluated using nine beta-hemolytic strains of GBS and one non-hemolytic strain of GBS at the LoD from 12 to 24 hours at 35°CThe enrichment broth was subcultured to a Tryptic Soy Agar plate with 5% sheep blood every two hours to confirm the presence of GBS. All hemolytic organisms tested produced some kind of orange color reaction by 16 hours and a definitive orange color reaction by 20 hours. All organisms, including the non-hemolytic strain tested, were recovered upon subculture of Strep B Carrot Broth™ One-Step at 12 hours. The incubation range for Strep B Carrot Broth™ was set from 16-24 hours.

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SPECIMEN STABILITY

Various types of specimen transport swabs were evaluated to determine the acceptable storage conditions required to recover GBS from Strep B Carrot Broth™ One-Step. Swabs were spiked with Group B Streptococci and a contrived matrix consisting of organisms commonly found in vaginal flora, kept at both room temperature and refrigerated conditions, and were inoculated to Carrot Broth at 0, 24, 48, 72, 96, and 120 hours. Eight different GBS strains were used in this study and were spiked into the contrived matrix near LoD. The contrived matrix containing non-target organisms consisted of E. faecalis, E. coli, C. albicans, and L. acidophilus. TransPRO™ swabs with Liquid Amies (flocked swab liquid-based transport system) and four types of Healthlink transport systems: Sponge-based Liquid Amies and Liquid Stuart's, and Gel-based: Amies Gel and Stuart's Gel were used in this study.

Strep B Carrot Broth™ One-Step was able to recover 8/8 (100%) of GBS strains and produce an orange coloration from Healthlink swabs in Liquid Amies, Stuart's liquid, Amies Gel, and Stuart's Gel when stored at 2-8°C for up to 96 hours. 100% of GBS strains also produced the expected orange color reaction from the flocked swab TransPRO™ Liquid Amies stored at 2-8°C for up to 120 hours. All transport systems tested saw a decline in recovery of GBS after 24 hours of room temperature storage.

REPRODUCIBILITY

Prior to initiating the study, a panel of 12 blinded isolates provided by Hardy Diagnostics was tested at three distinct study sites in triplicate on five work days to demonstrate reproducibility and to document proficiency in the performance of the test. Agreement of >95% with known test results was required before proceeding with the study. The testing was done with at least one operator and two readers, blinded to each other's results, per site. Strains in the reproducibility panel produced the expected color results with Strep B Carrot Broth™ One-Step >95% of the time at 24 hours. All non-hemolytic GBS isolates tested (100%) were recovered upon subculture to TSA with 5% Sheep's Blood.

CONCLUSIONS

The clinical and performance studies summarized above demonstrate the substantial equivalence of Strep B Carrot Broth™ One-Step to the predicate device.

Regulation Number and Section

§ 866.2360 Selective culture medium.

(a)
Identification. A selective culture medium is a device that consists primarily of liquid or solid biological materials intended for medical purposes to cultivate and identify certain pathogenic microorganisms. The device contains one or more components that suppress the growth of certain microorganisms while either promoting or not affecting the growth of other microorganisms. The device aids in the diagnosis of disease caused by pathogenic microorganisms and also provides epidemiological information on these diseases.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 866.9.