BBL CHROMAGAR 0157

K070691 · Becton, Dickinson & CO · JSI · Nov 20, 2007 · Microbiology

Device Facts

• Record ID: K070691
• Device Name: BBL CHROMAGAR 0157
• Applicant: Becton, Dickinson & CO
• Product Code: JSI · Microbiology
• Decision Date: Nov 20, 2007
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.2360
• Device Class: Class 1

Indications for Use

BBL™ CHROMagar™ 0157:H7 is a selective medium for the isolation, differentiation and presumptive identification of Escherichia coli 0517:H7 from human clinical stool specimens.

Device Story

BBL™ CHROMagar™ 0157:H7 is a prepared plated culture medium used in clinical laboratories. It incorporates chromogenic substrates and selective agents (potassium tellurite, cefixime, and cefsulodin) to isolate and differentiate E. coli O157:H7 from other fecal flora. When inoculated with a stool specimen and incubated for 18-24 hours, E. coli O157:H7 colonies hydrolyze specific chromogens to produce a distinct mauve color, allowing for presumptive identification. Non-target organisms appear as blue/blue-green or natural-colored colonies. The device is intended for use by laboratory professionals to assist in the identification of potential pathogens, with results requiring confirmation via biochemical or serological testing.

Clinical Evidence

Performance evaluated via retrospective user-based study (n=2855) and a field trial (n=126). Retrospective study showed 86.4% positive percent agreement and 99.8% negative percent agreement compared to SMAC. Field trial using frozen/archived isolates and fresh stools showed 98% positive agreement and 100% negative agreement. Analytical specificity testing (n=59 organisms) showed 100% sensitivity for E. coli O157:H7 and 98.3% specificity, with one false-positive noted for Salmonella Heidelberg. Bench testing confirmed growth within 18-24 hours in the presence of common stool-related substances.

Technological Characteristics

Selective culture medium containing chromogenic substrates and selective agents (potassium tellurite, cefixime, cefsulodin). Formulated with Difco peptones. Manual inoculation and visual interpretation. Storage at 2-8°C, incubation at 35 ± 2°C for 18-24 hours. Shelf life 12 weeks.

Indications for Use

Indicated for the isolation, differentiation, and presumptive identification of E. coli O157:H7 from human clinical stool specimens.

Regulatory Classification

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.

Predicate Devices

• BBL™ MacConkey II Agar with Sorbitol (SMAC) (K871855)

Submission Summary (Full Text)

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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY ONLY TEMPLATE

A. 510(k) Number:
K070691

B. Purpose for Submission:
Premarket notification

C. Measurand:
Escherichia coli 0157:H7

D. Type of Test:
Direct detection of *E. coli* 0157:H7 from fecal specimens using chromogenic substrate potassium tellurite, cefixime and cefsulodin - qualitative assay.

E. Applicant:
Becton, Dickinson and Company

F. Proprietary and Established Names:
BBL™ CHROMagar™ 0157:H7

G. Regulatory Information:

1. Regulation section:
866.2360 subjected to the limitation in 866.9 (c) (3)

2. Classification:
I

3. Product code:
JSI

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4. Panel:
83 Microbiology

H. Intended Use:

1. Intended use(s):
BBL™ CHROMagar™ 0157:H7 is a selective medium for the isolation, differentiation and presumptive identification of Escherichia coli 0517:H7 from human clinical stool specimens.

2. Indication(s) for use:
BBL™ CHROMagar™ 0157:H7 is a selective medium for the isolation, differentiation and presumptive identification of Escherichia coli 0517:H7 from human clinical stool specimens.

3. Special conditions for use statement(s):
Prescription Use

4. Special instrument requirements:
Not Applicable

I. Device Description:
BBL™ CHROMagar™ 0157 is a prepared plated medium. The formulation incorporates chromogenic substrates, which allow colonies of E. coli 0157:H7 to produce a mauve color for presumptive identification from the primary isolation plate and differentiation from other organisms.

J. Substantial Equivalence Information:

1. Predicate device name(s):
BBL™ MacConkey II Agar with Sorbitol (SMAC)

2. Predicate 510(k) number(s):
K871855

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3. Comparison with predicate:

| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Intended Use | For detection of E. coli 0157 | For detection of E. coli 0157 |
| Reporting Results | E. coli 0157 (Presumptive) | E. coli 0157 |
| Reading | Manual | Manual |
| Incubation | 18 -24 hr | 18-24 hr |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Inoculum | Direct fecal specimens | Isolated colonies from any source |
| Formula Differential Media | Uses a chromogenic mix as a differential media | Uses sorbitol and neutral red as a differential media |
| Formula Selective Media | Uses tellurite, cefixime and cefsulodin | Uses bile salts and crystal violet. |

K. Standard/Guidance Document Referenced (if applicable):

Not Applicable

L. Test Principle:

BBL™ CHROMagar™ 0157 formulation incorporates chromogenic substrates, which allow colonies of E. coli 0157:H7 to produce a mauve color for presumptive identification from the primary isolation plate and differentiation from other organism. Specially selected Difco™ peptones are incorporated to supply nutrients. Potassium tellurite, cefixime and cefsulodin act as selective agents which reduce the number of bacteria other than E. coli 0157:H7 that grow on this medium. The chromogenic mix consists of artificial substrates (chromogens), which release an insoluble colored compound when hydrolyzed by a specific enzyme. E. coli 0157:H7 utilizes one of the chromogenic substrates which produce mauve colored colonies. The growth of mauve colored colonies is considered presumptive identification for E. coli 0157:H7 on BBL™ CHROMagar™ 0157. Non-E. coli 0157:H7 bacteria may utilize other chromogenic substrates resulting in blue to blue-green colored colonies or, if none of the chromogenic substrates are utilized, colonies may appear as a natural color.

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M. Performance Characteristics (if/when applicable):

1. Analytical performance:

a. Precision/Reproducibility:

Reproducibility studies were conducted in triplicates at 3 sites, 2 external and 1 internal, using expected Escherichia coli O157:H7 QC isolates and a variety of Non-Escherichia coli O157:H7 isolates (Salmonella typhimurium, Escherichia coli H7 (Non O157), Shigella sonnei, and additional Escherichia coli). The intra-site and inter-site reproducibility for BBL CHROMagar O157 was ≥ 95%.

b. Linearity/assay reportable range:

Not Applicable

c. Traceability, Stability, Expected values (controls, calibrators, or methods):

Quality Control (QC) data was compiled across all three sites and all batches of BBL CHROMagar Escherichia coli O157:H7. The testing followed the recommendations of the QC strains listed in the package insert. This included the Escherichia coli O157:H7 ATCC™ 700728 as positive growth: light mauve to mauve colonies, Escherichia coli ATCC™ 25922: growth inhibition (partial to complete), and Enterobacter cloacae ATCC™ 13047 as growth: blue-green to blue colonies. All individual QC batches passed the acceptance criteria.

d. Detection limit:

Not Applicable

e. Analytical specificity:

A total of 59 organisms, representing several genera of stool pathogens and 5 E. coli 157:H7 were included in a cross reactivity testing. The stool pathogens included Salmonella spp., Shigella spp., Campylobacter spp., Yersinia spp., Plesiomonas spp., Aeromonas spp., Vibrio spp., and E. coli non-O157:H7. The identification of the microorganisms was blinded from the sites. The sites tested the organisms in three different lots and interpreted the results. The E. coli O157:H7 strains grew mauve colonies 15/15 times (100%). The non-E. coli O157:H7 strains showed non-mauve colonies 58/59 times per each lot for a total of 174/177 times (98.3%). Campylobacter fetus, BD645, which was frozen, did not grow on the original subculture media; therefore, this isolate was removed from the testing procedure. Additionally, one Salmonella spp. strain (S. Heidelberg) produced mauve colonies

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resembling *E. coli* 0157:H7. Therefore, a limitation statement indicating the possibility of false positive results with this particular strain was added to the package insert.

## Interference Study

An interference study was independently conducted in replicates five times using a variety of substances that may be present in stool or rectal specimens. Among the substances used were blood, water, K-Y Jelly, Vaseline, Hydrocortisone ointment, tucks pad, soap, Metamucil, Milk of Magnesia, Senna, Fleet Glycerin Suppository, and Dulcolax Suppository. The results showed that *E. coli* O157 grew on CHROMagar media within the claimed range of time in the presence of all of these substances.

### f. Assay cut-off:

Not Applicable

## 2. Comparison studies:

### a. Method comparison with predicate device:

Two external studies and one internal study were conducted on BBL™ CHROMagar O157.

#### i. A user-based retrospective study:

A collection of 3136 stool specimens were cultured, of which 2855 specimens provided acceptable results for this study. BBL CHROMagar O157:H7 were compared to SMAC media. Final results of the isolate identification were determined by additionally testing (biochemical, serology, or ID system) as recommended in the Package insert. Results produced a positive percent agreement of *Escherichia coli* O157:H7 of 86.4% (19/22) and a negative percent agreement of Non-*Escherichia coli* O157:H7 of 99.8% (2828/2833). However, for 281 isolates the sponsor reported “Not Available (NA)” data because a confirmation protocol was not followed as stated in the package insert.

#### ii. BBL™ CHROMagar™ O157 Field Trial in a regional hospital.

A collection of 110 frozen fecal isolates, 6 archived, frozen stools, and 10 fresh stool specimens were compared to SMAC, SMAC-CT and TSA II. Among the frozen and archived fecal isolates, 56 were Shiga toxin positive *E. coli* O157:H7 and the additional 60 were comprised of Shiga Toxin-positive *E. coli* Non-O157 (8), Shiga toxin-Negative *E. coli* (15), *Pseudomonas aeruginosa* (5), *Klebsiella* spp. (10), *Enterobacter* spp. (10), *Serratia* spp. (4), and *Proteus* spp. (8). Results produced a positive percent agreement of 98% (55/56) *E. coli* O157:H7 on CHROMagar O157:H7 and a negative percent agreement of 100% (60/60) for the non-*E. coli* O157:H7 strains. Additionally, CHROMagar O157 test results demonstrated that 1/10

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fresh stools were positive for *E. coli* O157:H7 and the remaining 9/10 were negative for *E. coli* O157:H7. These latter results were confirmed using biochemical tests, latex agglutination, and Premier EHEC.

b. Matrix comparison:
Not Applicable

3. Clinical studies:
a. Clinical Sensitivity:
Not Applicable
b. Clinical specificity:
Not Applicable
c. Other clinical supportive data (when a. and b. are not applicable):
As described in the package insert, interpretation of plate results must be completed within 18-24 hours after inoculation of the BBL CHROMagar O157:H7 plate. A separate time detection study measuring growth in 18-24 hours range of time was independently conducted. All organisms grew within the expected range of time.

4. Clinical cut-off:
Not Applicable

5. Expected values/Reference range:
Not Applicable

N. Proposed Labeling:
The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.

O. Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.