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The BACTEC™ MGIT™ Para TB Medium tube, supplemented with BACTEC MGIT Para TB Supplement, is intended for the detection and recovery of Mycobacterium paratuberculosis using the BACTEC MGIT System. Acceptable specimen types are decontaminated bovine fecal specimens.

M. paratuberculosis has been demonstrated to be the causative agent of Johne's disease, a chronic wasting disease of ruminants in general and dairy cattle in particular. M. paratuberculosis colonizes the lymphatic tissues of the animal's intestinal walls, causing chronic diarrhea and wasting, and eventually resulting in the animal's death.¹ Culture of the organism from fecal specimens is the most sensitive, definitive determination of the presence of M. paratuberculosis infestation within a herd of animals. The BACTEC MGIT Para TB Medium and BACTEC MGIT Para TB Supplement for M. paratuberculosis are designed to recover the organism from decontaminated bovine fecal specimens. The fully supplemented medium (including egg yolk) can detect as few as 1 to 10 viable organisms from processed specimens in < 49 days. The BACTEC MGIT Para TB Medium and BACTEC MGIT Para TB Supplement are designed to be a diagnostic tool to assist in Johne's monitoring and control programs. The BACTEC MGIT Para TB Medium tube contains 7 mL of modified Middlebrook 7H9 Broth base.^2,3 The medium has been modified to specifically stimulate the growth of M. paratuberculosis following extraction from decontaminated specimens. There are advantages and disadvantages to using liquid medium for this purpose. The advantage is that liquid medium is the best resuscitation and growth support medium for the quick recovery of mycobacteria from processed specimens. This is based on the utilization of the BACTEC 12B radiometric medium for the growth and recovery of M. paratuberculosis.⁴ The disadvantage is that liquid culture is much more sensitive to the quality of the inoculum in terms of remaining toxins and contaminants from the decontamination procedure.

Upon receipt of a shipment or lot of BACTEC MGIT Para TB Medium tubes, it is suggested that a suspension of the ATCC™ control organism shown in Table 1 be prepared in Middlebrook 7H9 Broth or Saline.

1. From solid media cultures less than 15 days old, prepare a suspension in Middlebrook 7H9 Broth or Saline.

2. Adjust the suspension to a turbidity equivalent to a McFarland No. 0.5 standard.

3. Dilute the control organism suspensions following the dilution scheme outlined in Table 1.

4. Unscrew the cap and aseptically add 800 µL of BACTEC MGIT Para TB supplement. Inoculate the supplemented tube with 500 µL of M. paratuberculosis ATCC 19698 (1:50,000 dilution). Tightly recap the tube and mix well. Enter the tube into the BACTEC MGIT 960 instrument.

The BACTEC MGIT Para TB Medium tubes should be detected as instrument positive within the time frame shown in Table 1. If the BACTEC MGIT Para TB Medium Quality Control tubes do not give the expected results, do not use the remaining tubes until you have contacted Technical Services at 800-638-8663 (United States only).

Table 1

For Veterinary Use.

This Product Contains Dry Natural Rubber.

Working with Mycobacterium avium subspecies paratuberculosis grown in culture requires Biosafety Level 2 (BSL-2) practices, containment equipment and facilities. Laboratory equipment and work surfaces should be decontaminated with an effective disinfectant on a routine basis, after work with infectious materials is finished, and especially after overt spills, splashes, or other contamination by infectious materials. Contaminated equipment must be decontaminated according to any local, state, or federal regulations before it is sent for repair or maintenance or packaged for transport in accordance with applicable local, state, or federal regulations, before removal from the facility.⁵

Prior to use, each MGIT Para TB tube should be examined for evidence of contamination or damage. Discard any tubes if they appear damaged or unsuitable.

In the event of tube breakage: 1) Close the instrument drawers; 2) Turn off the instrument; 3) Consult your facility guidelines. An inoculated leaking or broken vial may produce an aerosol of mycobacteria; appropriate handling should be observed.

Autoclave all inoculated MGIT Para TB tubes prior to disposal.