Mycobacterium

Characteristics:

- Slow growing (1 division per day, vs. for example E.coli, 1 division per hour).

- The 'fast growing' (< 7 days) is also exist.

- M. tuberculosis grows > 7 days.

- Acid fast.

- Also survive in the nature, i.e. M. gordonae is considered as lab contaminants and M. chelonae in the water.

Specimens and pretreatments

- from an expected sterile stie (i.e. pleura space, cerebrospinal fluid, synovial fluid) --> no pretreatment needed.

- from other sites, acid is needed to kill other bacteria than Mycobacterium.

- from patients with cystic fibrosis, chlor based addition is added to liquify the sample.

Further steps

- buffer is added to the specimens.

- platted to Lowenstein agar.

- on this agar, M. tuberculosis grows after 14 days. If < 7 days, probably not m. tuberculosis.

- M. tuberculosis in Lowenstein not pigmented, rough and sticks really well to the agar. Other mycobacterium that behave like this is M. abcessus, but it does not stick to the agar really well and fast grower.

- When something grow in the agar, antibiogram can be performed.

   - Pyrazinamide can be performed within minutes.

   - Rifampicine, Isonizaid and Ethambutol needs 21 days.

     To read this, the control should have 100 CFU/ quadrant.

     Resistant is when >1% grow compared to control.

- Further identification of M. tuberculosis can be performed using additional tests:

   - biochemical (M. tuberculosis is niacin and nitrate test positive).

   - Mycobacterium ID system. (M. tuberculosis peak 24 > 26 and a specific peak is present).

Safety

- All in containment level 3.

- When you spill something on the bench. 

   - Do not panic.

   - Find a masker.

   - Cover the spillage with wet tissues.

   - Spray alcohol from outside in, in the area.

   - Leave the room, warn your colleague.

   - After 2 hours, you can comeback and clean the spillage (you are the one who know what you did).

- When you spill something in the flow chamber.

   - close the chamber.

   - leave the room, also for 2 hours at least.

- For other people in the room.

   - do not panic.

   - hold your breath.

   - leave the room.