BBL MGIT PRODUCTS

K954932 · Becton Dickinson Diagnostic Instrument Systems · MDB · Aug 21, 1996 · Microbiology

Device Facts

• Record ID: K954932
• Device Name: BBL MGIT PRODUCTS
• Applicant: Becton Dickinson Diagnostic Instrument Systems
• Product Code: MDB · Microbiology
• Decision Date: Aug 21, 1996
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.2560
• Device Class: Class 1

Intended Use

The BBL® MGIT™ Mycobacteria Growth Indicator Tube supplemented with BBL® MGIT™ OADC and BBL® MGIT™ PANTA antibiotic, mixture, when appropriate, is intended for the detection and recovery of mycobacteria. Acceptable specimen types are digested and decontaminated clinical specimens (except urine) and sterile body fluids (except blood).

Device Story

BBL® MGIT™ is a selective culture medium for mycobacteria detection. Device consists of a tube containing modified Middlebrook 7H9 broth base, OADC enrichment, and PANTA antibiotic mixture. A fluorescent compound embedded in a silicone rubber base at the tube bottom acts as an oxygen sensor. Inoculated specimens are incubated at 37°C. Actively respiring mycobacteria consume dissolved oxygen, causing the sensor to fluoresce under longwave UV light. Clinicians manually compare tube fluorescence against positive and negative control tubes to interpret results. Fluorescence indicates presumptive positive growth. The device provides a non-radiometric alternative to traditional systems for mycobacterial recovery in clinical microbiology laboratories.

Clinical Evidence

Multi-site study (6 sites, 2801 specimens) compared BBL® MGIT™ to BACTEC® 460TB and BBL® SEPTI-CHEK® AFB. 318 positive specimens yielded 330 isolates. BBL® MGIT™ recovered 253 (77%) isolates; BACTEC®/SEPTI-CHEK® recovered 260 (79%); conventional solid media recovered 219 (66%). Average time-to-detection for MGIT was 14.1 days. False positive rate was 0.5%; breakthrough contamination rate was 9.7%. MGIT failed to recover 3.7% of isolates found by reference systems.

Technological Characteristics

Modified Middlebrook 7H9 broth base; OADC enrichment (oleic acid, albumin, dextrose, catalase); PANTA antibiotic mixture (polymixin B, amphotericin B, nalidixic acid, trimethoprim, azlocillin). Detection via O2-sensitive fluorescent sensor in silicone rubber base. Manual observation of fluorescence under longwave UV light. Incubation at 37°C ± 1°C. Standalone culture tube format.

Indications for Use

Indicated for the detection and recovery of mycobacteria from digested and decontaminated clinical specimens (excluding urine) and sterile body fluids (excluding blood).

Regulatory Classification

Identification

A microbial growth monitor is a device intended for medical purposes that measures the concentration of bacteria suspended in a liquid medium by measuring changes in light scattering properties, optical density, electrical impedance, or by making direct bacterial counts. The device aids in the diagnosis of disease caused by pathogenic microorganisms.

Predicate Devices

• BACTEC® 460TB System
• BBL® SEPTI-CHEK® AFB Mycobacteria Culture System

Submission Summary (Full Text)

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Becton Dickinson Microbiology Systems
7 Loveton Circle
Sparks, Maryland 21152-0999
[phone]
K954932

# BECTON DICKINSON

510(k) SUMMARY
AUG 21 1996

**SUBMITTED BY:**
BECTON DICKINSON MICROBIOLOGY SYSTEMS
7 Loveton Circle
Sparks, MD 21152

**CONTACT:**
DENnis R. Mertz, Manager of Regulatory Affairs
**TELEPHONE:**
[phone]

**PREPARED:**
August 13, 1996

**TRADE NAME:**
BBL® MGIT™ Products

**COMMON NAME:**
Selective Culture Medium

**CLASSIFICATION NAME:**
Selective Culture Medium

**PREDICATE DEVICES:**
BACTEC® 460TB System
BBL® SEPTI-CHEK® AFB Mycobacteria Culture System

**INTENDED USE:**
The BBL® MGIT™ Mycobacteria Growth Indicator Tube supplemented with BBL® MGIT™ OADC and BBL® MGIT™ PANTA antibiotic, mixture, when appropriate, is intended for the detection and recovery of mycobacteria. Acceptable specimen types are digested and decontaminated clinical specimens (except urine) and sterile body fluids (except blood).

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# DEVICE DESCRIPTION:

The BBL® MGIT™ Mycobacteria Growth Indicator Tube contains 4 mL of modified Middlebrook 7H9 Broth Base. The complete medium is supplemented with 0.5 mL OADC enrichment and 0.1 mL of PANTA antibiotic mixture, when necessary. The medium components are substances essential for the growth of mycobacteria. A fluorescent compound is embedded in the bottom of the BBL® MGIT™ tube which is sensitive to the presence of oxygen dissolved in the broth.

Specimens are inoculated (0.5 mL) into the BBL® MGIT™ tube and incubated at the appropriate temperature. Tubes are read daily from the second day of inoculation.

Actively respiring microorganisms consume the oxygen and allow the compound to fluoresce. Each inoculated BBL® MGIT™ tube is compared to the fluorescence Positive Control and Negative Control tube to assist in the interpretation of a positive signal from the BBL® MGIT™ tube.

A BBL® MGIT™ tube which exhibits fluorescence comparable to the Positive Control tube is considered presumptively positive for growth.

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DEVICE TECHNOLOGICAL CHARACTERISTICS:

Tables 1 & 2 summarize the similarities and differences between the BBL® MGIT™ tube and the predicate devices.

Table 1: Comparison of BBL® MGIT™ to the BACTEC® 460TB System

| | BBL® MGIT™ | BACTEC® 460TB |
| --- | --- | --- |
| Intended Use | Growth and detection of mycobacteria from clinical specimens (excluding blood and urine). | Growth and detection of mycobacteria from clinical specimens. |
| Sample Type | Primary sample type - respiratory; other body fluids acceptable (excluding blood and urine). | Primary sample type - respiratory; other body fluids (excluding blood) acceptable. |
| Sample Volume | 0.5 mL | 0.5 - 1.0 mL |
| Reactive Ingredient Concentrations of Growth Medium | APPROX. COMPOSITION/1000 mL | APPROX. COMPOSITION/1000 mL |
| | Na₂HPO₄ 2.5 g | Na₂HPO₄ 2.5 g |
| | L-Asparagine 1.25 | |
| | KH₂PO₄ 1.0 | KH₂PO₄ 1.0 |
| | Sodium glutamate 0.5 | Sodium glutamate 0.5 |
| | (NH₄)₂SO₄ 0.5 | (NH₄)₂SO₄ 0.5 |
| | Sodium citrate 0.1 | Sodium citrate 0.1 |
| | MgSO₄·7H₂O 0.5 | MgSO₄·7H₂O 0.05 |
| | Ferric ammonium citrate 0.04 | Ferric ammonium citrate 0.04 |
| | CuSO₄·5H₂O 1.0 mg | CuSO₄·5H₂O 1.0 mg |
| | Pyroxidine 1.0 | Pyroxidine 1.0 |
| | ZnSO₄·7H₂O 1.0 | ZnSO₄·7H₂O 1.0 |
| | Biotin 0.5 | Biotin 0.5 |
| | CaCl₂·2H₂O 0.5 | CaCl₂·2H₂O 0.5 |
| | Casein Peptone 1.25 g | |
| | Glycerol 3.1 mL | |
| | Casein Hydrolysate 0.1 g | |
| Additional Medium Growth Factors | BBL® MGIT™ OADC enrichment: Oleic Acid, Albumin, Dextrose, Catalase | Albumin, Catalase |
| Detector | O₂ sensitive fluorescent sensor in silicone rubber base. | ¹⁴C labeled fatty acid present in the medium. |
| Antimicrobial Supplement | BBL® MGIT™ PANTA™ antibiotic mixture: Polymixin B, amphotericin B, nalidixic acid, trimethoprim & azlocillin. | BACTEC® PANTA™ PLUS: Polymixin B, amphotericin B, nalidixic acid, trimethoprim & azlocillin. |
| Growth Detection | Manual observation of fluorescence via excitation with longwave UV light. Fluorescence results from O₂ consumption by mycobacterial growth. | Radiometric detection of ¹⁴CO₂ liberated by mycobacterial growth. |
| Incubation Temperature | 37° C ± 1° C | 37° C ± 1° C |

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Table 2: Comparison of BBL® MGIT™ to BBL® SEPTI-CHEK® AFB

| | BBL® MGIT™ | | BBL® SEPTI-CHEK® AFB | |
| --- | --- | --- | --- | --- |
| Intended Use | Growth and detection of mycobacteria from clinical specimens. | | Growth and detection of mycobacteria from clinical specimens. | |
| Sample Type | Primary sample type - respiratory; other body fluids acceptable (excluding blood and urine). | | Primary sample type - respiratory; other body fluids acceptable (excluding blood). | |
| Sample Volume | 0.5 mL | | 0.5 - 1.0 mL | |
| Reactive Ingredient Concentrations of Growth Medium | APPROX. COMPOSITION/1000 mL | | APPROX. COMPOSITION/1000 mL | |
| | Na₂HPO₄ | 2.5 g | Na₂HPO₄ | 1.579 g |
| | L-Asparagine | 1.25 | | |
| | KH₂PO₄ | 1.0 | KH₂PO₄ | 1.579 |
| | Sodium glutamate | 0.5 | L-Glutamic acid | 0.526 |
| | (NH₄)₂SO₄ | 0.5 | (NH₄)₂SO₄ | 0.526 |
| | Sodium citrate | 0.1 | Sodium citrate | 0.421 |
| | MgSO₄·7H₂O | 0.5 | MgSO₃·7H₂O | 0.053 |
| | Ferric ammonium citrate | 0.04 | Ferric ammonium citrate | 0.042 |
| | CuSO₄·5H₂O | 1.0 mg | | |
| | Pyroxidine | 1.0 | | |
| | ZnSO₄·7H₂O | 1.0 | | |
| | Biotin | 0.5 | Biotin | 5.0 mg |
| | CaCl₂·2H₂O | 0.5 | CaCl₂·2H₂O | 0.5 |
| | Casein Peptone | 1.25 g | Casein hydrolysate | 1.053 g |
| | Glycerol | 3.1 mL | | |
| | | | NaCl | 0.895 |
| | | Malachite Green | 1.0 mg | |
| Additional Medium Growth Factors | BBL® MGIT™ OADC enrichment: Oleic Acid, Albumin, Dextrose, Catalase | | BBL® SEPTI-CHEK® AFB Mycobacterial Culture Supplement: Oleic Acid, Albumin, Dextrose, Catalase | |
| Other Growth Media as Part of System | None | | BBL® SEPTI-CHEK® AFB Slide: Middlebrook 7H11 Agar Egg based agar medium Chocolate Agar | |
| Detector | O₂ sensitive fluorescent sensor in silicone rubber base. | | None | |
| Antimicrobial Supplement | BBL® MGIT™ PANTA™ antibiotic mixture: Polymixin B, amphotericin B, nalidixic acid, trimethoprim & azlocillin. | | BBL® SEPTI-CHEK® AFB Mycobacterial Culture Supplement: Polymixin B, amphotericin B, nalidixic acid, trimethoprim & azlocillin. | |
| Growth Detection | Manual observation of fluorescence via excitation with longwave UV light. Fluorescence results from O₂ consumption by mycobacterial growth. | | Macroscopic observance of growth on agar and/or in broth. | |
| Incubation Temperature | 37° C ± 1° C | | 37° C ± 1° C | |

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# SUMMARY OF DEVICE TESTING:

Internal testing of the BBL® MGIT™ tubes demonstrated the ability to recover a wide variety of mycobacterial species. Additionally, internal testing showed comparable recovery between the BACTEC® 460TB System and the BBL® MGIT™ tubes.

An external evaluation was performed at six (6) sites. Four (4) sites used the BACTEC® 460TB System and conventional solid agar media as reference methods for comparison to the BBL® MGIT™ tubes. Two (2) sites used the BBL® SEPTI-CHEK® AFB Mycobacteria Culture System as the reference method for comparison to the BBL® MGIT™ tubes. A combined total of 2801 specimens were evaluated. The distribution of specimens tested by source was respiratory (78%), gastric (0.4%), body fluid (9.8%), tissue (7.0%), stool (2.5%) and other (2.4%). A total of 318 specimens were positive which represented 330 isolates recovered during the study.

Of these 330 isolates, 253 (77%) were recovered by the BBL® MGIT™ tubes, 260 (79%) were recovered by the BACTEC® 460TB System and the BBL® SEPTI-CHEK® AFB and 219 (66%) were recovered by conventional solid media. The average time-to-detection for the BBL® MGIT™ tubes for All mycobacteria was 14.1 days. The BBL® MGIT™ tubes demonstrated a 0.5% false positive rate (MGIT fluorescent, no AFB present). The BBL® MGIT™ tubes failed to recover 3.7% of the isolates which were recovered in one or more of the reference systems (BACTEC® 460TB, BBL® SEPTI-CHEK® AFB or conventional solid media). While this percentage represents a potential loss of recovery, it is not indicative of an actual false negative determination (refer to "Limitations of the Procedure" section). Use of a second medium, as recommended, will increase the probability of recovery of mycobacterial organisms. The average breakthrough contamination rate for the BBL® MGIT™ tubes was 9.7%.

# CONCLUSIONS

Based on the internal and external evaluation of the BBL® MGIT™ tubes, the overall performance of the BBL® MGIT™ tubes is comparable to the BACTEC® 460TB System and the BBL® SEPTI-CHEK® AFB Mycobacterial Culture System; therefore, we believe the BBL® MGIT™ tube to be substantially equivalent to these devices.