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Liquid Culture (LC) and Line Probe Assay (LPA) specimen processing involves pre-treatment of the sputum specimens.

Digestion and decontamination are usually done using N-acetyl-l-cysteine–sodium hydroxide (NALC- NaOH) method: 

• The process is essential to free TB bacilli from the mucus cells/ tissue.
• This also helps in decontamination by killing normal flora that grows more rapidly than the TB bacilli. 

NALC-NaOH Method for Sample Processing
 

Biomedical Waste Management is an essential biosafety component of TB containment laboratories. All infectious materials should be decontaminated, incinerated, buried or autoclaved.

The following materials are suitable for waste disposal by autoclaving:

• All positive TB cultures 
• Mycobacterial cultures 
• All infectious materials from TB-containment laboratories where mycobacterial culture is performed

Sputum culture conversion - The transition in sputum culture results from a positive sample growing Mycobacterium tuberculosis to two consecutive negative cultures separated by at least 30 days.

Time to culture conversion is the interval between treatment initiation to date of specimen collection of the first (of the two) negative culture.

Disinfectants used in lab settings include:

1% Sodium Hypochlorite

• Broad spectrum antimicrobial action
• Used to disinfect surfaces
• Used to disinfect infectious material and disposal of used Truenat consumables (reagent bottles, cartridges, tips, chips) 
• Hazardous and corrosive, to be used with care
• Is highly alkaline so can corrode metal
• Waste soaked in Sodium Hypochlorite should not be discarded by autoclaving. 

70% Alcohol

Security of laboratory data and confidentiality of TB patient data are important. Hence, it is recommended to archive or take periodic data backup.

The Truelab Analyzer has an internal memory to store 20000 test results. The digital data can be transmitted through connectivity via email, SIM card, Wi-Fi or Bluetooth.

Recommended ways of documenting the results and archiving data are:

Daily maintenance of Truelab and Trueprep instruments performed by the laboratory personnel includes:

It is common in laboratories to see specimens with the following particles which may potentially alter nucleic acid amplification test (NAAT) results:

• Food particles
• Blood
• Tobacco
• Pan
• Debris or tissue pieces

These interfering substances cause failures in Truenat assays and may have inhibitory effects on CBNAAT assays. This interferes with the accuracy of results, leading to false positive or negative tests and delayed cycle threshold values.

The results for Nucleic Acid Amplification Test (NAAT) assays are entered in Culture and Drug Susceptibility Testing (C&DST) register. The key variables entered are shown in the table below.

Truenat Mycobacterium tuberculosis (MTB) and Truenat MTB Rifampicin (Rif) Dx Assays amplify target genes through Polymerase Chain Reaction (PCR).

The presence of mutant gene is detected using probe melt assay.

The target genes include:

Daily maintenance tasks of the CBNAAT instrument include:

At the end of the day:

• Turn off the computer
• Turn off the CBNAAT instrument

At the beginning of the day:

• Turn on the CBNAAT instrument
• Turn on the computer

Daily Maintenance Tasks