A0

Use of Micro Centrifuge

• Designed for the separation of materials through sedimentation using centripetal force​
• Used in DNA Extraction Room​ to concentrate specimens during processing

Components and Use (Figure)

Use of Hot Air Oven 

• For heating non-explosive substances and objects ​ 
• For dry heat sterilization  
• During DNA extraction step​; kills Mycobacterium tuberculosis and partially lyses the cells at 95^oC

​Installation of the Hot Air Oven (Figure 1)

Use of Micropipette  

• Micropipette (Figure) dispenses and aspirates liquid (reagent, sample). ​ 
• IT is used in the DNA Extraction Room, Master Mix Room, Amplification Room and Hybridization Room to dispense reagents for Line Probe Assay (LPA). ​ 
• A micropipette should be dedicated to each room and labelled accordingly. 

Figure: Micropipette

Cleaning:  

Procedural biosafety measures include: 

• Biosafety measures taken during the Line Probe Assay (LPA) procedures ​ 
• Aerosol generation and preventive measures​ 

Manipulations that produce aerosols in DNA Extraction Room are: 

• Pipetting​ 
• Centrifugation​ 
• Vortexing​ 
• Discarding micropipette tips after use​ 

Measures to Prevent Aerosol Generation ​ 

Line Probe Assay (LPA) lab personnel must comply with Good Laboratory Practices for their biosafety.  

These include technical competency in: 

• Performing tests 
• Using Personal Protective Equipment (PPE) 
• Using equipment 
• Handling infectious materials 
• Keeping work areas clean 
• Using disinfectants 
• Waste management practices 
• Understanding responsibility for protecting themselves and others 

Do’s and Don’t of Good Laboratory Practices

The refrigerated centrifuge is used in the mycobacteriology laboratory for concentrating bacterial cells, following the processing of sputum or other specimens. It is also used for spinning down reagents from walls of containers. The temperature maintained within the refrigerator centrifuge is 4°C to reduce the percentage of mycobacteria killed due to heat generated during centrifugation. The required G force is 3000 x g (not RPM).

Essential Features of the Refrigerated Centrifuge 

Brain Heart Infusion (BHI) Agar is a general-purpose medium​ that is:

• Prepared using dehydrated ingredients
• Suitable to grow bacteria, yeasts and moulds​
• ​Used for reagent quality control and contamination check for liquid culture​.

To check contamination in Mycobacteria Growth Indicator Tube (MGIT) broth:

The procedure for processing gastric aspirates in TB cultures is as follows:

The procedure for processing pus and other muco-purulent specimens in TB cultures is as follows:

Extrapulmonary specimens are divided into 2 groups based on the site and mode of collection and the extent of contamination: