CDST_LT-M10: CBNAAT

Cartridge Based Nucleic Acid Amplification Test (CBNAAT) is a rapid molecular diagnostic test. It is used for diagnosis of Tuberculosis (TB) and Rif-resistant Tuberculosis (RR-TB) in NTEP. Results are obtained from unprocessed sputum samples in about 2hours which helps in early detection and treatment of TB patients. 

India has vast number of CBNAAT laboratories which are utilized for TB/RR-TB detection and Universal Drug Susceptibility Testing (UDST) under the National TB Elimination Program (NTEP).  

Figure: CBNAAT Cartridge and Machine in Use (Image courtesy: USAID supported Challenge TB Project)

The CB-NAAT system detects DNA sequences specific for Mycobacterium tuberculosis complex and rifampicin resistance by Polymerase Chain Reaction (PCR). It concentrates Mycobacterium tuberculosis bacilli from sputum samples, isolates genomic material from the captured bacteria by sonication and subsequently amplifies the genomic DNA by PCR. The process identifies clinically relevant rifampicin resistance-inducing mutations in the RNA polymerase beta (rpoB) gene in the Mycobacterium tuberculosis genome in a real-time format using fluorescent probes called molecular beacons.

 

Video: Cartridge-Based Nucleic Acid Amplification Test [CBNAAT] - GeneXpert Technology 

Resources

• Training Module (1-4) for Program Managers and Medical Officers, NTEP, MoHFW, 2020.
• India TB Report 2021, National TB Elimination Program (NTEP), MoHFW, 2021.

 

Assessment Questions

 

Question	Answer 1	Answer 2	Answer3	Answer 4	Correct Answer	Correct explanation	Part of pre-test	Part of post-test
Under NTEP, CBNAAT is offered upfront for which of these categories?	PLHIV	Paediatric presumptive TB	Presumptive DR-TB	All of the above	4	Under NTEP, CBNAAT is recommended upfront for People living with HIV, Paediatric Presumptive TB patients, Presumptive DR-TB patients and patients notified from the Private sector.	Yes	Yes
CBNAAT requires the processing of sputum samples before testing	True	False			2	Results are obtained from unprocessed sputum samples in about 2hours from a CBNAAT machine	Yes	Yes

 

The CBNAAT module contains components that enable automated sample processing in the cartridge, and filling of the tube with the sample-reagent mixture for Polymerase Chain Reaction (PCR), followed by PCR amplification and detection.

 

The structure of the CBNAAT module is described below and shown in Figure 1:

• Syringe pump drive or plunger motor: Dispenses fluids into the different cartridge chambers
• I-CORE module: Performs PCR amplification and detection
• A cartridge loading and unloading mechanism ensures the proper movement of the cartridge in the instrument
• Reaction/PCR tube: Enables rapid thermal cycling and optical excitation and detection of the tube contents. The reaction tube is automatically inserted into the I-CORE module (hardware for PCR amplification and fluorescence detection) when the cartridge is loaded into the instrument.
• Valve drive: Rotates the cartridge valves to align the chambers with the syringe
• Ultrasonic horn: Lyses the sample

 

Figure 1: Structure of the CBNAAT module

 

The interior region of the cartridge insertion site also called cartridge bay and is shown in Figure 2.

 

Figure 2: Interior of the Cartridge Bay

Mode of Operation of the CBNAAT Module 

• The Intelligent Cooling/Heating Optical Reaction (I-CORE) module is the hardware component, within each instrument module, that performs PCR amplification and, fluorescence detection.
• As part of the cartridge load process, the PCR tube is inserted into the ICORE module. 
• As the test starts, the sample and reagent mixture are pushed from the cartridge, into the PCR tube.
• During the amplification process, the ICORE heater heats up and the fan cools down the reaction tube contents.

Within the I-CORE, there is an optical system composed of two blocks: A six colour excitor and detector block excite the dye molecules, and detect the fluorescence emitted.

 

Figure 3: Mode of operation of the CBNAAT module

 

Resources

 

• Training material Cepheid Hbdc 3a GeneXpert technology

 

Kindly provide your valuable feedback on the page to the link provided HERE

The disposable, single-use CBNAAT cartridge is a closed system unit to hold the samples and reagents. Inside of a CBNAAT Cartridge (CBNAAT operator manual). Each cartridge consists of the following components:

• Processing chambers: Hold samples, reagents, processed samples, and waste solutions. One chamber is designated as an air chamber to equilibrate pressures within the cartridge.
• Valve body: Rotates and allows fluid to move to different cartridge chambers and to the reaction tube. Within the valve body, the specimen is isolated, PCR inhibitors are removed, and the sample is mixed with PCR reagents and moved into the integrated reaction tube.
• Reaction tube: Enables rapid thermal cycling and optical excitation and detection of the tube contents. The reaction tube is automatically inserted into the I-CORE module (hardware for PCR amplification and fluorescence detection) when the cartridge is loaded into the instrument.

Resources

• CBNAAT operator manual

The consumables required at a Cartridge-based Nucleic Acid Amplification Testing (CBNAAT) laboratory include the following:

CBNAAT/ GeneXpert Dx System consisting of CBNAAT machine preloaded with assay software, Computer and the Barcode reader

• CBNAAT assay kit (Figure) consisting of:
  • CBNAAT cartridges: Kit contains 10 or 50 individually packed cartridges.
  • CBNAAT reagent: 8 ml volume pack per cartridge. The sample reagent solution is clear but may range from colourless to golden yellow.
  • Sterile pipette: Individually packed, disposable transfer pipettes, one per each test, with a single mark for the minimum volume of sample transfer to each cartridge.
  • CD containing the Assay Definition File.

Figure: Contents of CBNAAT Assay Kit; Source: GLI Training Package for CBNAAT.

• Sputum containers 

 

• Personal protective equipment:
  • Laboratory coats
  • Disposable gloves
     
• Disinfectants
  • 1% Sodium hypochlorite solution 
  • 5% Phenol
  • 70% Ethanol 
     

• Power stabiliser (UPS) for uninterrupted power supply to perform CBNAAT assay.

   

Resources

• GLI Training Package for CBNAAT.  
• FIND Diagnosis for All, CBNAAT SOP.

Assessment

Question​	Answer 1​	Answer 2​	Answer 3​	Answer 4​	Correct answer​	Correct explanation​	Page id​	Part of Pre-test​	Part of Post-test​
What are the components of the CBNAAT assay kit?	CBNAAT cartridges	CBNAAT reagent	Sterile pipette	All the 3	4	CBNAAT assay kit includes CBNAAT cartridges, CBNAAT reagent and sterile pipette.	​	Yes	Yes

Cartridge-based Nucleic Acid Amplification Test (CBNAAT) is used to detect Mycobacteria tuberculosis and rifampicin-resistance using GeneXpert IV Dx system and the Xpert MTB/ RIF cartridge.

The CBNAAT system integrates and automates sample processing, nucleic acid amplification, and detection of Mycobacteria tuberculosis and rifampicin resistance.

The system utilises the use of single-use disposable CBNAAT cartridges that hold the Polymerase Chain Reaction (PCR) reagents and hosts the PCR process.

The process involves the following steps:

1. Sample processing: Specimens are processed by adding the sample reagent at 2:1 (v/v) ratio to the sputum sample, mixing and incubation for 15 minutes at room temperature. The sputum sample get liquified after the processing step.
2. Loading sample into cartridge: Liquefied sample is added to the cartridge using a transfer pipette.
3. Setting up the machine to run the test: After switching on the system, “Create Test” (Figure A) is clicked in the GeneXpert Dx system window, test details are added, the barcode label of the cartridge is scanned (Figure B) and “Start Test” (Figure C) is clicked to initiate testing.

Figure: Setting the machine to run the assay by creating test (A), adding test details, scanning barcode (B) to start test (C); Source: GLI Training Package for CBNAAT.

4. Loading the cartridge: The instrument module door which displays the blinking green light is opened to load the cartridge. The door of module is closed firmly (an audible click sound should be heard). The green light stops blinking when the test starts.
5. Obtaining the results: When the test is finished, the green light turns off. It takes around 1 hour 55 minutes to complete test run. On completion of test run, the result is generated automatically on the monitor.
6. Ending the test run: When the system releases the door lock at the end of run, the module door is opened to remove the cartridge. The used cartridge is discarded.

 

Resources

• GLI Training Package for CBNAAT.  
• FIND Diadnosis for All, CBNAAT SOP.

 

Assessment

Question​	Answer 1​	Answer 2​	Answer 3​	Answer 4​	Correct answer​	Correct explanation​	Page id​	Part of Pre-test​	Part of Post-test​
Barcode is present on sterile pipette and CBNAAT cartridge.	True	False			2	Barcode is present on CBNAAT cartridge.	​	Yes	Yes

 

Introduction

Cartridge-based Nucleic Acid Amplification Test (CBNAAT) is an automated rapid molecular diagnostic test which detects targeted Deoxyribonucleic Acids (DNA) sequences of Mycobacterium tuberculosis (M.tb) genome by Real-time Polymerase Chain Reaction (RT-PCR) method.

CBNAAT uses the GeneXpert IV Dx system and the single-use disposable Xpert M.tb/ Rifampicin (RIF) cartridges that hold the Polymerase Chain Reaction (PCR) reagents and host the PCR process.

The various TB tests utilizing the CBNAAT platform:

1) GeneXpert MTB/ RIF

• The Xpert M.tb/ RIF assay is a Nucleic Acid Amplification Test (NAAT) that uses a disposable cartridge with the GeneXpert Instrument System to quickly identify possible Multidrug-resistant TB (MDR-TB) that is resistant to RIF.
• This test yields rapid results, i.e., within 2 hours and is therefore cost and time-saving.

2) GeneXpert MTB/ RIF Ultra 

• The Xpert M.tb/ RIF Ultra assay is similar to the Xpert MTB/ RIF assay, just that it is even faster with a higher level of accuracy.
• The results are obtained in 80 minutes.
• It can detect paucibacillary TB disease.

3) GeneXpert MTB/ XDR

• This is a GeneXpert M.tb assay that detects mutations associated with Resistance Towards Isoniazid (INH), Fluoroquinolones (FLQ), Second Line Injectable Drug (SLID) (amikacin, kanamycin, capreomycin) and Ethionamide (ETH) in a single test.

4) GeneXpert Omni/Edge

• GeneXpert Omni/Edge is a battery-operated, wireless and web-enabled portable molecular diagnostics system, intended for use as the point-of-care diagnostic tool in remote and challenging settings.
• It is a single-slot platform i.e., runs one test per cycle, uses a 2-in-1 tablet/laptop and a compact printer and is expected to enable accurate, fast and cost effective test results.

Apart from TB, the CBNAAT platform can be used to diagnose several other pathogens using different cartridges. One of the common other pathogens detected using CBNAAT in India is COVID-19.

Note: Except GeneXpert MTB/ RIF , other CBNAAT tests are not currently being endorsed by NTEP.

Resources

• WHO Consolidated Guidelines on Tuberculosis. Module 3: Diagnosis - Rapid Diagnostics for Tuberculosis Detection 2021 Update.
• Guidelines for Programmatic Management of Drug-resistant TB (PMDT) in India; NTEP, CTD, MoHFW, India, 2021.
• Sachdeva K, Shrivastava T. CBNAAT: A Boon for Early Diagnosis of Tuberculosis-Head and Neck; Indian J Otolaryngol Head Neck Surg, 2018.

Assessment

Question	Answer 1	Answer 2	Answer 3	Answer 4	Correct answer	Correct explanation	Page id	Part of Pre-test	Part of Post-test
‘Xpert M.tb/ RIF Ultra yields results faster than Xpert M.tb/ RIF’.	True	False			1	Xpert M.tb/ RIF Ultra yields results in approx. 80 minutes compared to Xpert M.tb/ RIF which gives results in approx. 110 minutes.		Yes	Yes
GeneXpert MTB/ RIF is the only CBNAAT tests that is endorsed by NTEP.	True	False			1	Other tests using CBNAAT platform GeneXpert MTB/ RIF Ultra, GeneXpert MTB/ XDR and GeneXpert Omni/Edge are not endorsed by NTEP.		Yes	Yes

 

The CBNAAT System automatically performs internal quality control for each sample. 

During each test, the system uses the following inbuilt controls:

System Check Control (SCC)

• Checks integrity of the instrument, cartridges and PCR reagents.

Sample Processing Control (SPC)

• Ensures that a sample is correctly processed.
• Included in the cartridge and is processed with the sample. The DNA is detected by a PCR assay.

Probe Check Control (PCC)

• Performed during the first stage of the test.
• Verifies the presence and integrity of the labelled probes.

Video 1: CBNAAT Technology -Inbuilt Controls

 

 

Video 2: Summary of all In-built Control Checks

Resources

• CBNAAT Operator Manual.

The CBNAAT system integrates and automates sample processing with amplification and detection of the target sequences

For sample processing, sample reagent is provided in CBNAAT kit, 8ml volume pack per each cartridge

• The sample reagent solution is clear but may range from colourless to golden yellow

Processing of clinical specimens should be performed as per laboratory biosafety standards

• Treat all sputum specimens as potentially infectious
• Wear protective gloves and laboratory coats when handling specimens and reagents

Sample processing from direct sputum and decontaminated sputum sediments is described in the Video given below - 

Video 1: Sample processing from direct sputum; Source: Challenge TB: Sample Processing Sputum

 

Video : Specimen Processing for CBNAAT 

Resources

• Challenge TB: Sample Processing Sputum

The following procedures are recommended when processing various body fluids with the Cartridge-based Nucleic Acid Amplification Test (CBNAAT):

Bronchoalveolar Lavage (BAL): 

Processing of BAL for CBNAAT assay is given here. However, it is important that each laboratory optimizes this protocol to minimize the error rate.

If the BAL volume is sufficient (approx. 5 ml), centrifuge and dissolve sediment into 1 ml sterile phosphate buffer/ saline, then add sample reagent in a 1:2 ratio.

If the BAL volume is less (less than 5 ml), take 1 ml and add 2 ml of sample reagent.

• If the BAL is mucoid or has more than 0.5% blood contamination, decontaminate using N-acetyl-l-cysteine–sodium hydroxide (NALC-NaOH) treatment.
• Decontamination of BAL should also be carried out if the error rate is more than 2%.

Pericardial/ Ascitic/ Synovial Fluid:

If the sample volume exceeds 5 ml, centrifuge and dissolve sediment into sterile phosphate buffer/saline to make volume 1 ml, then add sample reagent in a 1:2 ratio.

If the sample volume is less than 5 ml, take 1 ml and add 2 ml of sample reagent.

• Pleural fluid is a suboptimal sample, and pleural biopsy is preferred. 
• A positive CBNAAT result in pleural/body fluid can be treated as TB, a negative result should be followed by other tests.
• Decontaminate/concentrate using standard NALC-NaOH treatment if bloody (more than 0.5% blood), thick and/or clots are present.

Pus/ Abscess/ Aspirates/ Semen:

• Liquid/ slightly viscous specimen: Use sample-to-sample reagent 1:2 ratio, mix well and follow routine CBNAAT protocol.
• If very thick, viscous or bloody specimens: Add 2 ml sample reagent to 0.2 - 0.3 ml pus, mix well to the vortex, and increase the incubation time, if required.
• Decontaminate, if required (>0.5 % blood).

*Each laboratory must optimize these protocols to minimize the error rate.

Resources

• Xpert MTB/RIF Assay for the Diagnosis of Pulmonary and Extrapulmonary TB

• Use the sterile transfer pipette provided in the CBNAAT kit to draw liquefied sample into the transfer pipette
  • The minimum amount to be loaded into the cartridge is 2 ml
  • Do not process the sample if there is insufficient volume
• Open the cartridge lid
• Transfer the sample into the open port (Figure 1) of the CBNAAT cartridge and dispense slowly to minimize the risk of aerosol formation

 

Figure 1: CBNAAT cartridge (top view) to show the open port
(SOP for GeneXpert MTB/RIF)

• Discard the transfer pipette
• Snap the lid shut to close firmly
• Turn on the CBNAAT instrument
• Open the instrument module door, which displays the blinking green light
• Load the cartridge and close the door of the module firmly
• The test should be started within 30 minutes of adding liquefied sample to the cartridge
• The remaining liquefied sample may be kept for up to 12 hours at 2-8°C (for repeat testing)

 

Video 1: CBNAAT loading

 

 

Video 2: Sample Loading (Demonstration)

Resources

• SOP for GeneXpert MTB/RIF

The test results of the Cartridge-based Nucleic Acid Amplification Test (CBNAAT) assay are displayed in the ‘View Results’ window, of the CBNAAT software.

 

For visualizing the results after the test is completed:

• In the CBNAAT Dx System window, click View Results on the menu bar.
• The View Results window appears.
• To select a test result, click View Test.
• ‘Select Test to Be Viewed’ - dialog box appears.
• Select the test of interest.
• Click OK.

 

Note: The selected test result appears in the ‘View Results’ window. A result will be displayed in PDF format. 

 

To generate a PDF report

• To generate a report in PDF format, click on “Report” and then select the result you want.
• The PDF report will be generated.

 

Interpretation of Test Results

• The ‘View Results’ window displays information about the test, such as sample ID and run-time on the left-hand side panel.
• The interpretation of the result is in the center, and the real-time PCR amplification curves are displayed at the bottom.   

 

Figure: User 'View Results' Window showing the information about test, interpretation of results and real-time PCR curves

 

 

Resources

 

• GeneXpert MTB/RIF Package Insert, p12-13.

 

Kindly provide your valuable feedback on the page to the link provided HERE

On completion of a test run, the Cartridge-based Nucleic Acid Amplification Test (CBNAAT) gives the following results:

1. MTB DETECTED; Rif Resistance DETECTED
2. MTB DETECTED; Rif Resistance NOT DETECTED
3. MTB DETECTED; Rif Resistance INDETERMINATE
4. MTB NOT DETECTED
5. Error
6. Invalid
7. No result

Conclusive results include: MTB NOT DETECTED, MTB DETECTED with Rif Resistance/ without Rif Resistance.

Non-conclusive results include: MTB Detected, Rif Resistance Indeterminate, Errors, Invalid and No Result - the test has to be repeated in these cases.

 

Figure: CBNAAT Result Algorithm

 

 

Video : CBNAAT Results Interpretation

Resources

• Guidelines for Programmatic Management of Drug-resistant Tuberculosis in India, MoHFW, 2017.
• GeneXpert Dx System Operator Manual

The Cartridge-based Nucleic Acid Amplification Test (CBNAAT) test has some limitations such as:

1. Bacterial load below the Limit of Detection (LOD ~ 130 CFU/ml) may result in a false-negative result.
2. Patients on an anti-TB regimen can still have positive results due to killed bacilli in the specimen and hence cannot be used for follow-up.
3. A positive test result does not necessarily indicate the presence of viable organisms. It is, however, presumptive for the presence of Mycobacterium tuberculosis (MTB) and Rifampicin (Rif) resistance.
4. MTB detection is dependent on the number of organisms present in the sample. Quality specimen collection and timely processing of the sample will minimize the errors.
5. Test results might be affected by anti-TB medication. Therefore, therapeutic success or failure cannot be assessed using this test, because DNA might persist following antimicrobial therapy.
6. Mutations or polymorphisms in primer or probe binding regions may affect the detection of new or unknown MDR or Rif-resistant strains, resulting in a false-negative result.
7. Any modification in sample processing may alter the performance of the test.
8. Results should be interpreted in conjunction with clinical data available to the clinician.

Video:  

CBNAAT Assay Limitations

Resources

• GenXpert Manual Version 4.7b.
• Cepheid Training Resource; Module 9: Troubleshooting, p13-20.

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.

Table: Key Variables entered in C&DST Register; Source: Guidelines for PMDT in India, 2021.

VARIABLES SET 1	VARIABLES SET 2	VARIABLES SET 3	VARIABLES SET 4
Test ID	Health Facility (HF) name	Residential district	Current facility HF type
Date of test updated in Nikshay	Lab type	Type of test	Predominant symptom
Date tested	Patient ID	Reason for testing	Predominant symptom duration
Date reported	Episode ID	Treatment status	History of Anti-TB Treatment (ATT)
Test status	Name	Diagnosis date	No. of Health Care Provider (HCP) visited before the diagnosis of the current episode
Type of specimen	Gender	TB treatment start date	The visual appearance of sputum
Date of specimen collection	Age	Current facility state
State name	Primary phone	Current facility district
District name	Address	Current facility TB Unit (TU)
TB unit	Residential state	Current facility HF

 

NAAT results are reported in the results section of “Request Form for examination of biological specimen for TB” including:

• Select Type of test: Cartridge-based Nucleic Acid Amplification Test (CBNAAT)/ TrueNAT
• Select Sample: A/B
• Select M. tuberculosis: Detected/ Not Detected/ Not Available (NA)
• Select Rif Resistance: Detected/ Not Detected/ Indeterminate/ NA
• Select Test: No result/ Invalid/ Error; Error code
• Date tested
• Date Reported
• Reported by (name and signature)
• Laboratory name

Video : CBNAAT/Truenat Results Entry in Lab Register

Resources

• Guidelines for Programmatic Management of Drug Resistant Tuberculosis in India, 2021.

The assay needs to be repeated by using a new cartridge if one of the following test results occur:

INVALID: An INVALID result indicates that Sample Processing Control (SPC) failed. The sample was not properly processed, or Polymerase Chain Reaction (PCR) was inhibited.

ERROR: An ERROR indicates that Probe Check Control (PCC) failed, and the assay was aborted possibly due to the reaction chamber being filled improperly, a reagent probe integrity, syringe pressure issues, or failure of the CBNAAT module.

NO RESULT: A NO RESULT indicates that insufficient data were collected. For example, the operator stopped a test that was in progress.

RIF Indeterminate: RIF indeterminate result indicates that the sample has a less bacterial load.

Program guidelines recommend obtaining a second specimen to confirm rifampicin resistance in these scenarios.

 

How to Perform the Retest?

• Leftover sputum or fresh sputum or reconstituted sediment: 

Treat it with a new Sample Reagent (SR) and load it into the new CBNAAT cartridge.

• Sufficient leftover SR-treated sample: 

Use within 4 hours of initial addition of SR to the sample - Load into the new CBNAAT cartridge.

Do not use SR-treated sample if it is more than 4 hours old - Over-treatment may lead to false-positive test results.

Always use a new cartridge! 

Video : Retest Protocol for CBNAAT

Resources

• GeneXpert Xpress SARS-CoV-2: Instructions for Use, Cepheid Manual.

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.

Hence, it is important to follow certain precautions when collecting the specimen to avoid contaminating the specimen with these substances.

In such situations, the following protocol needs to be followed:

• Reject frank blood/bloody samples; however, the presence of blood up until 30% does not interfere in Truenat assays
• For samples containing food/tobacco/tissue particles that cause interference in processing:
  • Use a fresh sample, if available
  • Use a sample after food particles or tissue pieces settle/sediment; otherwise, reject the sample

​

Figure: Blood in Sputum Sample Interferes with PCR

Resources

• Truenat MTB Pack Insert.
• Truenat MTB Rif Pack Insert.
• Laboratory Diagnosis of Tuberculosis by Sputum Microscopy, GLI Initiative

The most common situations that need troubleshooting while using CBNAAT are:

• Hardware or instrument problems
• Failures without error codes 
• Failures with error codes 

 

Troubleshooting Approach

1. In case of an issue, a message will be displayed (often with an error code). 
2. Check if the error affects one particular module. 
3. Refer to the CBNAAT user manual and follow the recommended corrective action.

 

If the problem persists, continue to use other modules in the meantime (if possible), and exclude the faulty modules from the tests. Contact the technical support team.

 

How to reach the technical support team?

 

 

Resources

 

• GeneXpert Current Operator Manual.
• Cepheid HBDC Training: Troubleshooting.

 

Kindly provide your valuable feedback on the page to the link provided HERE

 

If the barcode scanner is not working, enter the cartridge barcode manually (Figure):

• Step 1: Click on “Create Test”
• Step 2: A dialogue box - Scan Cartridge Barcode will appear. Click on “Manual Entry”
• Step 3: Manually type the 2-line numbers of the cartridges

Figure: Process for Manual Entry of the Cartridge Barcode

 

In case of barcode reader failure, while using a new lot, this action cannot be performed. Contact the manufacturer or technical support to collect the Lot Specific Parameter.

Also, contact customer care for repair or replacement of the barcode reader.

Resources

• GeneXpert MTB/RIF Assay Package Insert, Section K, p15.

This hardware problem occurs when a cartridge is stuck inside a CBNAAT module.

Causes

• Module mechanical malfunction during the test
• Electrical failure

Solutions for releasing a stuck cartridge

Solution 1: Verify that the module door is not open. Gently try to open the module door.

Solution 2: Try to remove the cartridge from the software.

• In the CBNAAT System window, click ‘Maintenance’ on the menu bar and select ‘Open Module Door or Update EEPROM’ (see the figure below).
• Select the module. Click “Open Door” to open the module door.

​

Figure: CBNAAT system showing ‘Open Module Door’ and ‘Perform Self-Test’

 

Solution 3: If the door does not open, close the software, and re-launch the software.

When the software is re-launched, the module will reinitialize itself by putting the valve and the syringe in the correct position. This may help to open the door.

Solution 4: Turn the system off and restart the CBNAAT instrument and software.

Solution 5: In the CBNAAT system window, choose ‘Maintenance’ on the menu bar and select ‘Perform Self-Test' (see figure above).

Solution 6: If none of the solutions above work, manually remove the cartridge.

If the cartridge is not released, contact technical support, to manually remove the cartridge. If you are a senior lab supervisor, you may click here to see the steps to manually remove a stuck cartridge.

Video : CBNAAT Hardware Problem: Stuck Cartridge

 

Resources

• Cepheid HBDC Troubleshooting Manual.
• Xpert MTB/RIF Training Package, Module 9, GLI Initiative

One of the common problems encountered while using the CBNAAT machine is the non-detection of the module.

Usually, there is a loss of communication between modules and software, leading to non-detection.

Origins:

• Ethernet connection between Personal Computer (PC) and CBNAAT is bad
• Power supply issue (main power or Universal Power Supply (UPS) fluctuations)
• Bad connection points between gateway board and modules
• Too high room temperature 

Solutions:

• Restart the instrument first and then the computer.
• Unplug and re-plug the ethernet cable between the PC and the instrument, then restart as above.
• Secure the power supply and use an adapted UPS/ surge protector.
• Check the temperature inside the module (should be below 39°C).

Figure: Troubleshooting protocol for the non-detection of CBNAAT Module

 

Video : CBNAAT Hardware Problem: Modules Not Detected

Resources

• GeneXpert Package Insert, L.5, p19

While using the CBNAAT machine in a laboratory setting, many different causes can lead to an error (indicated on-screen as ‘ERROR’, as in figure 1).

Figure 1: Window showing how to click on “Errors” to learn more about the issue

Error Message Categories

The errors are displayed by the instrument’s software to highlight various technical issues that disrupt the test process. They are grouped into five categories by the software:

1. Cartridge loading errors: Errors that occur during a cartridge loading process
2. Self-test errors: Errors that occur during the self-test process
3. Run-time errors: Errors that occur during a test.
4. Operation terminated errors: Errors that abort a test
5. Post-run analysis errors: Errors that occur during the data reduction process

You can view the errors by clicking the ‘Check Status’ icon on the CBNAAT software, as seen in figure 2.

Figure 2: 'Check Status' Window of the CBNAAT Software

 

Monitoring of Errors and Invalid/ No Results

• Rates of errors and Invalid/ No Results need to be monitored by the module and user.
• Identifying the most frequent types of problems can help to troubleshoot since certain errors may be associated with a user’s technique in sample processing while others with mechanical problems with the instrument modules or room temperature.
• Recurring errors should be timely reported to the manufacturer.

 

Figure 3: Monitoring of Errors on CBNAAT

 

Video : Monitoring Different Types of Errors with CBNAAT

 

Resources

• GeneXpert Package Insert.
• Xpert MTB/RIF Training Package, Module 9, GLI Initiative

Errors 5006, 5007, 5008 and 5009 (Probe Check Control Failed) sometimes appear on the Cartridge-based Nucleic Acid Amplification Test (CBNAAT) machine in TB laboratories and need troubleshooting.

Problem:

Probe Check Control (PCC) failed, and the test was stopped before amplification.

Origins:

• Incorrect storage of cartridges (probe integrity issues detected)
• Dust on optical filters
• Sample too viscous
• Incorrect sample volume
• Improper fluid transfer (bubbles)

Solutions:

• Store the kits between 2 - 28°C.
• Use an optical brush to clean the optical filters (without a cleaning solution).
• Make sure the sample is totally liquified before transferring it to the cartridges.
• Add the correct volume of the specimen.
• Avoid making bubbles.

 

Video : CBNAAT Troubleshooting: Error- 5006, 5007, 5008 and 5009 [PCC Failed]

 

Video : Probe Check Control (PCC)

Resources

• GeneXpert Package Insert

During the use of the Cartridge-based Nucleic Acid Amplification Test (CBNAAT) machine, Error- 2008 and 2009 may appear on the screen and needs troubleshooting.

Problem:

2008: Pressure reading exceeds the maximum

2009: Syringe pressure is below the protocol limit

Figure: Error 2008

Origins:

• The cartridge filter is clogged (due to too viscous sample or particles)
• Pressure sensor failed

Solutions:

• Make sure the sample does not contain any solid particles.
• Make sure the sample is totally liquified before transferring it to the cartridges.
• If after 15 minutes of incubation with the sample reagent, the sample is still too viscous, wait up to 10 more minutes.
• Use a new cartridge and add only a sample reagent to test. If the problem persists, it is likely a module problem: Contact Technical Support.

 

Video : CBNAAT Troubleshooting: Error- 2008 and 2009

Resources

• GeneXpert Package Insert

Error - 2014, 3074, 3075 and 1001, in the Cartridge-based Nucleic Acid Amplification Test (CBNAAT) machine are related to ‘Heating Component Related Issues’.

Problem:

Temperature/ Heater Failure

Origins:

• High temperature in module 
• Heater component failure 
• Broken fan 
• Dust on filter near the fan

Troubleshooting:

In the CBNAAT Dx System window:

• Click “Maintenance” on the menu bar
• Select “Module Reporters” to check module temperature

Figure: Troubleshooting Heating Component Related Issues

 

If the problem persists, one needs to contact the manufacturer for technical support.

 

Video : CBNAAT Troubleshooting: Error- 2014, 3074, 3075 and 1001 [Heating Component Related Issues]

Resources

• GeneXpert Package Insert

Some Cartridge-based Nucleic Acid Amplification Test (CBNAAT) machine errors will indicate test failure without Error Codes.

Error: Invalid

Problem: 

Sample Processing Control (SPC) failed.

Origin: 

Polymerase Chain Reaction (PCR) was inhibited due to food particles or blood in the sample.

Solution:  

Laboratory Technician (LT) needs to collect another specimen, if necessary.

Prevention: 

• Before mixing with the sample reagent for decontamination, check whether the sample contains food particles or blood. 
• Allow food particles to settle down before adding the sample to the cartridge.

If the problem persists, one needs to contact the manufacturer for technical support.

Figure: Error - Invalid

 

Error: No Result

Problem:

Test could not be completed and insufficient data collected.

Origins:

Software stops working before the test is completed due to: 

• Windows or software freeze 
• Power failure 
• STOP TEST function was activated (accidentally or deliberately)

Solution:

Secure the power supply, restart the machine and repeat the test with a new cartridge.

Contact an authorized service provider if the problem persists.

Figure: Error - No Result

 

Video : CBNAAT Troubleshooting: Failures without Error Codes

Resources

• GeneXpert Package Insert

Maintenance of the CBNAAT instrument is an essential activity to be performed in the laboratory setting and involves:

Preventive Maintenance Tasks

• Performed regularly by the user
• Ensure the good performance of the system
• Avoid problems of malfunction

Need-based Maintenance Tasks

• Performed in specific situations
• Performed or guided by manufacturer representatives

 

Frequency-based Tasks for the CBNAAT Instrument

DAILY	WEEKLY	MONTHLY	ANNUAL OR AFTER 2000 TESTS PER MODULE
Remove and properly dispose off cartridges Clean and disinfect the work area Put on a dust cover when the instrument is not in use	Disinfect the instrument’s surface Disinfect cartridge bay interior and plunger rod Filter cleaning	Disinfect cartridge bay interior and plunger rod Clean instrument filter  Archive and back-up test results Filter cleaning	Module Xpert Check (calibration) and maintenance of the module

Materials Required for CBNAAT Instrument  Maintenance

• Freshly prepared 1% sodium hypochlorite solution
• 70% Ethanol
• Wipes, tissues, or cotton
• Disposable gloves 
• Clean water and soap (for washing the filters)
• Replacement filters for the fan (available from the manufacturer). 

 

Resources

• GeneXpert Package Insert. 

It is important to adhere to the manufacturer's installation guide for optimal performance of the Cartridge-based Nucleic Acid Amplification Test (CBNAAT) machine. This guide should be kept in the laboratory. It is important to thoroughly read the instalment steps given in the brochure supplied with the machine.

Strict monitoring of these criteria should be carried out by the laboratory personnel:

• The instrument should not be kept directly under an air-conditioning vent or window. Direct sunlight should also be avoided.​
• The instrument's room should have temperature control (15-30°C).
• The instrument needs to be installed on a vibration free/ stable workbench with no centrifuge adjacent to it.
• There is a need for a stable electricity supply (for added safety, the instrument must be connected to an Uninterruptible Power Supply (UPS) or surge protector).

For safety purposes, one needs to provide 10 - 15 cm of clearance on each side of the instrument. 

Compliance with equipment installation criteria is necessary. The Instrument Qualification Documents include:

1. Installation Qualification - IQ
2. Operational Qualification - OQ
3. Performance Qualification - PQ

Installation Qualification

IQ provides evidence for the delivery, installation and configuration of the instrument as per the manufacturer’s standards using an installation checklist.

Operational Qualification

OQ is a collection of test cases used to verify the proper functioning of a system before the instrument is released for use.

Performance Qualification

PQ is a collection of test cases used to verify that the system performs as expected under simulated real-world conditions.

 

Video : CBNAAT Instrument Installation Criteria

Resources

• GeneXpert Package Insert

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

• After testing, remove the cartridges from the instrument. 
• Dispose off cartridges in the appropriate biohazard waste container.
• Remove clutter from the work area.
• Disinfect the work area (1% hypochlorite solution or 70% ethanol).
• Put on the dust cover when the instrument is not in use.
• Switch off the machine at the end of the day.
• Do not turn off the UPS power supply.

It is essential to wear disposable gloves for the cleaning procedure. Wearing gloves prevents one from being exposed to biologically hazardous samples.

Video : Daily Maintenance of CBNAAT Instrument

Resources

• GeneXpert Package Insert

Monthly maintenance tasks of the CBNAAT instrument include:

Cleaning of the Cartridge Bay and Plunger Rod

The CBNAAT manufacturer recommends monthly cleaning of the cartridge bay and plunger rod. However, if the sample load is high, this task can be carried out on a weekly basis.

Cleaning of Module PCR Slot (Figure 1)

• Wear laboratory gloves.
• Remove cartridges from the modules.
• Make sure that all the bristles are fully inserted (up to the shoulder of the plastic shank of the brush).
• Brush the inside of the slot with up and down movements.
• Rotate the brush for approx. 180º and back, then repeat the previous step 2 times.
• Clean each module for at least 30 seconds.

Figure 1: Cleaning of Module PCR Slot

 

Plunger Disinfection (Figure 2-7)

Plunger maintenance is initiated using the CBNAAT software. While cleaning, care should be taken not to touch the slit on the I-CORE module into which the cartridge reaction tube is inserted. Make sure that the cleaning cloth is damp but not dripping with disinfecting liquid.

1. To initiate the task, click on the “Maintenance” icon on the toolbar (Figure 2).

Figure 2: "Maintenance" icon on the toolbar

2. On the Maintenance menu, select “Plunger Maintenance” (Figure 3).

 

Figure 3: "Plunger Maintenance" in the Maintenance Menu

 

3. In the “Plunger Maintenance” window, select a module to clean or select “Clean All” (Figure 4).

 

Figure 4: Selecting "Clean All" in the Plunger Maintenance Window

 

4. Follow the instructions in the Dialog box.

5. Click “OK” (Figure 5).

Figure 5: Click "OK" after following instructions in dialog box

6. The plunger rod in the chosen module will be automatically lowered (Figure 6).

Figure 6: Plunger Rod of Module

7. After cleaning the plungers, click on “Move Up All” and the plungers will return to their original position (Figure 7).

8.  Click “Close”.

 

Figure 7: Click "Move Up All" and then "Close" after cleaning the plungers

 

Replacing and Cleaning the Fan Filters (Figure 8)

Clean the fan filters weekly if you operate in an area of high pollution, dust or smoke, otherwise monthly/ quarterly is sufficient.

Figure 8: Steps for removing and replacing the filters

 

General Cleaning Procedure Outline

 

Make sure you wear disposable gloves for the cleaning procedure. Wearing gloves prevents you from being exposed to biologically hazardous samples.

Items required for cleaning:

• 1% Sodium hypochlorite solution (prepared within one day)
• 70% Ethanol
• Cotton swabs
• Disposable gloves
• Optical brush

 

Note:  The current guidelines from the manufacturer suggest the use of freshly prepared 1% sodium hypochlorite (or 1:10 solution of household chlorine bleach).

1. Dampen wipe/ swab with freshly prepared 1% sodium hypochlorite.
2. Wipe the surface/ element.
3. Discard the used wipe/ swab.
4. Wait for 2 minutes.
5. Dampen wipe/ swab with 70% Ethanol.
6. Wipe the surface/ element.
7. Repeat steps 5-7 three times.

 

Video : Monthly Maintenance of the CBNAAT Instrument

Resources

• GeneXpert Maintenance: GeneXpert Dx System, Cepheid, 2021.
• GeneXpert Maintenance Manual, 2013

The Cartridge-based Nucleic Acid Amplification Test (CBNAAT) files should be archived and saved to a CD or other appropriate external media (preferably an external drive), at least once a month to ensure that no test data are lost.

Archiving tests creates copies of the test data in “gxx” files. 

Importance of Archiving and Back-up 

Archiving allows you to:

1. Back-up data to ensure it will not be lost if the computer breaks down.

2. Create a copy of the data to be sent to the manufacturer for assistance in troubleshooting problems.

 

How to Archive Results

1. Click “Data Management” (Figure 1).

2. Click on “Archive Test” (Figure 1).

3. Choose the tests that need to be archived (or “Select All”) (Figure 1).

 

Figure 1: Steps to archive results

 

4. In the next dialogue box click “Proceed” (Figure 2).

5. The files will be saved in the folder “Export”. In the file name, you will see the date of archiving (Figure 2).

6. Click on “Save” (Figure 2).

7. Click “OK” (Figure 2).

 

Figure 2: Steps to archive results (continued)

 

 

How to Retrieve Results

1. Click “Data Management” and then click “Retrieve Test” (Figure 3).

2. Select the file you want to retrieve.

3. Click on” Open” (Figure 3).

 

Figure 3: Steps to retrieve results

4. Select the test you may want to retrieve (or “Select All”) (Figure 4).

5. Click “OK” (Figure 4).

6. Click on “Proceed” (Figure 4).

7. Click “OK” (Figure 4).

 

Figure 4: Steps to retrieve results (continued)

 

 

How to Back-up Data

Data backup should be carried out monthly.

1. Click “Yes” to the prompt (Figure 5).

2. Click on “Database Backup” (Figure 5).

3. Click on “Proceed” (Figure 5).

 

Figure 5: Steps to back-up data

 

4. The software will create a zip file with all the results (Figure 6).

 

Figure 6: Software creates a zip file for all results

5. The file is saved on the desktop in the CBNAAT folder -> Backup section.

6. Click on “Save” (Figure 7).

7. Click “OK” (Figure 7).

 

Figure 7: Steps to back-up data (continued)

 

Video : CBNAAT Monthly Data Archive and Data Back-up Process

 

Resources

• GeneXpert Maintenance: GeneXpert Dx System, Cepheid, 2021.
• GeneXpert Maintenance Manual, 2013

The annual maintenance protocol for the Cartridge-based Nucleic Acid Amplification Test (CBNAAT) instrument involves calibration of the machine. 

Calibration:

• Calibration of the CBNAAT instrument is performed by the manufacturer before the system is shipped.
• Calibration is not required during the initial system setup.
• The manufacturer recommends that the system should be checked for proper calibration on an annual basis (or after every 2,000 runs on each instrument module).
• Based on the usage and care of the system, calibration checks may be recommended more frequently.
• The service engineer will perform the machine check during the annual maintenance visit.

Parameters Verified During Calibration 

One calibration cartridge is used to calibrate a single module in conjunction with the calibration software.

• Recalibrate the optical system 
• Verify the thermal system 
• Module sub-system functionality: A series of system-level tests to ensure full system functionality within the instrument servicing specifications as provided by the manufacturer, and covers:

1. Heater and fan performance
2. Syringe drive and pressure performance
3. Valve drive performance
4. Ultrasonic horn performance
5. Electronic components performance

Figure: Temperature Calibration of the CBNAAT Instrument

 

Resources

• GeneXpert Package Insert

External Quality Assurance (EQA) ensures that high-quality testing can be carried out efficiently and without interruption. It involves Proficiency Testing (PT) and On-site Evaluation (OSE).

 

PT is an important component of EQA for Cartridge-based Nucleic Acid Test (CBNAAT) under the National TB Elimination Program (NTEP) and guarantees accurate and reproducible results.

 

Importance of EQA/ PT for CBNAAT

 

• Gives assurance to users that the instrument is functioning properly
• Checks to verify that users can correctly interpret and report results
• Verifies that there are no major errors in the process control system and that samples are identified, tested and reported correctly
• Helps to recognize major problems with an instrument or user and take remedial action

 

Process of EQA for CBNAAT

 

1. EQA of CBNAAT is done using dried tube panels consisting of Mycobacterium tuberculosis (MTB) strains that are RIF resistant/ sensitive/ Non-tuberculous Mycobacteria (NTM)/ negative.
2. Coordination of the EQA activity, manufacture and validation of the panels is undertaken by the National TB Institute, Bangalore.
3. The process of manufacturing and validating the Dried Tube Specimen (DTS) for EQA panels involves:
   • Culturing the mycobacterial strain in the liquid culture system followed by inactivation of the cultures using sample reagents
   • Further incubating for 84 days for confirmation of inactivation followed by preparation of DTS panel cultures and their validation.
4. Once validated, the DTS panels are dispatched to the CBNAAT sites

Each CBNAAT site receives a set of 5 tubes/ machine.

Ideally, EQA/ PT for CBNAAT is done thrice in a year/ per module/ per site.

 

Based on the performance of the CBNAAT laboratory, corrective actions are taken by the supervising authority such as Intermediate Reference Laboratory (IRL)/ National Reference Laboratory (NRL). During the on-site visits by the IRL and the NRL, quality indicators for CBNAAT are evaluated and corrective actions are suggested.

 

 

Resources

 

• GeneXpert Package Insert.
• NTI Laboratory Division.

 

Kindly provide your valuable feedback on the page to the link provided HERE

Monitoring of quality indicators is an essential component of quality assurance for the Cartridge-based Nucleic Acid Amplification Test (CBNAAT).

• Routine monitoring of quality (performance) indicators:
  1. Critical element of quality assurance for any diagnostic test 
  2. International Organisation of Standardisation (ISO) requirement
• Each testing site should collect and analyze quality indicators monthly.
• Document and investigate any unexplained change in quality indicators, such as:
  1. Increase in error rates
  2. Change in Mycobacterium tuberculosis (MTB) positivity rate or Rifampicin (Rif) resistance rate
  3. Significant change in volume of tests conducted
  4. Error rates > pre-determined threshold (>5%)
  5. Test turnaround time
• All unexpected trends should be reviewed by the laboratory manager and linked to corrective actions.
• Standard set of quality indicators should be used for all CBNAAT testing sites.
• System should be in place for centralized reporting of monthly quality indicators.
• Each instrument should be monitored monthly, using the following minimum set of indicators to evaluate proper use:
  1. Number of tests performed per month
  2. Number and proportion of MTB detected; Rif-resistance not detected
  3. Number and proportion of MTB detected; Rif-resistance detected
  4. Number and proportion of MTB detected, Rif-indeterminate
  5. Number and proportion of MTB not detected
  6. Number and proportion of errors
  7. Number and proportion of invalid results
  8. Number and proportion of no results
  9. Median time to result after receipt of the specimen

 

Figure: Monthly Quality Indicators for CBNAAT

 

Where possible, disaggregated data according to the tested population group (HIV positive, Multi-drug resistance (MDR) risk, extrapulmonary or paediatric TB) is collected.

 

Quality Indicator Monitoring: Troubleshooting Aid

Identifying the number and type of various errors can help with troubleshooting since certain errors may be associated with processing, instrumental or environmental conditions

The following analyses may be performed:

• The number of errors occurring by user
• The number of errors occurring by instrument module
• The number of tests lost due to power outages or surges
• The number, duration and causes of routine interruptions in the CBNAAT testing service

 

Video : Monitoring of CBNAAT Quality Indicators

Resources

• NTEP Monthly Quality Indicator Sheet

It is essential to follow biosafety protocols while handling specimens and cartridges. This will prevent anyone handling the specimens and cartridges from getting infected.

 

General Biosafety Requirements for CBNAAT

Cartridge-based Nucleic Acid Amplification Test (CBNAAT) is a low-risk procedure and requires the same level of precautions, like those used for direct Acid-fast Bacillus (AFB) sputum smear microscopy:

1. Carry out the procedure in a well-ventilated area.
2. Wear gloves and a laboratory coat at all times when handling patient samples.
3. Minimize the generation of aerosols during sample processing and handle specimens carefully and responsibly.

 

Based on risk assessment, additional biosafety precautions may be required in CBNAAT laboratories, such as the use of N95 respirators or biosafety cabinets.

 

Personal Protective Equipment (PPE) is important, but it does not replace good microbiological and good laboratory practices. They include:

 

Gloves: Essential (disposable and powder-free)

 

Laboratory coats: Essential

 

Respirators: Usually not required, but:

• May be needed, based on risk assessment.
• Must always be included in a spill kit.
• Recommended respirators are N95 or chosen based on program guidelines.

 

 

Precautions to take while preparing samples for CBNAAT testing

• The sample reagent should be added to the specimen in such a manner that the procedure minimizes aerosol generation.
• Although the sample reagent inactivates M. tuberculosis bacilli, it reduces, but does not eliminate, the biosafety risk to the laboratory technician.
• There is an increased risk of generating aerosols when splitting and handling concentrated and extrapulmonary TB specimens. These procedures must be performed in a certified biosafety cabinet.

 

Precautions during cartridge loading and transport

• When transferring cartridges to the machine for loading, an appropriate size enclosed container should be used.
• Care should be taken, as samples may leak if the cartridges are toppled during transport.

 

 

Resources

 

• GeneXpert MTB/RIF Assay Package Insert.

 

Kindly provide your valuable feedback on the page to the link provided HERE

Disposal of biohazardous waste is essential to prevent contamination and possible infection of those handling the infected specimens.

At the end of each day, Cartridge-based Nucleic Acid Amplification Test (CBNAAT) laboratories generate contaminated material such as:

• Used sputum containers
• Used cartridges
• Transfer pipettes.

All used materials should be considered contaminated.

All infectious samples should be sealed in a biohazard bag and disposed off according to Biohazard Waste Disposal Guidelines under the National Pollution Control Guidelines, 2019.

• Contaminated materials should be picked up with a gloved hand and placed in a closed lid container of 5% phenol solution or a biohazard bag.
• At the end of the day, the phenol should be drained, and the materials/ bags should be autoclaved at 121°C at 15 psi pressure for 20 minutes.
• Once done, the materials should be cooled and sent to the common waste treatment facility for mutilation/ shredding or disposal.

It is a good practice to display the Standard Operating Procedures (SOPs) for the disposal of each item in the CBNAAT laboratory.

Resources

• Guidelines for Management of Healthcare Waste as per Biomedical Waste Management Rules, 2016

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

• Bactericidal action
• Used for surface decontamination only
• Highly inflammable; keep away from fire
• Used to disinfect biosafety cabinets, laboratory benches and surface of instruments.

 

5% Phenol

• Used for decontaminating Cartridge-based Nucleic Acid Amplification Testing (CBNAAT) equipment and single-use items like CBNAAT cartridges prior to disposal
• Highly irritating to the skin, eyes and mucous membranes.

 

Preparation of these disinfectants is described below.

 

Preparation of 1% Sodium Hypochlorite

• Use commercially available 4% sodium hypochlorite solution.
• Dilute with distilled water to prepare required amount of 1% sodium hypochlorite
  • E.g.: To prepare 100 ml of 1% sodium hypochlorite: 75 ml distilled water plus 25 ml 4% sodium hypochlorite solution.
• Sodium hypochlorite solutions (domestic bleach) contain 50 g/l available chlorine, and should therefore be diluted to 1:50 or 1:10 in water to obtain the final concentrations of 1 g/l or 5 g/l when used as a general-purpose disinfectant for TB laboratories.
• To be prepared fresh.

 

Preparation of 70% Alcohol

• Use commercially available absolute alcohol.
• Dilute with distilled water to prepare the required amount of 70% alcohol
  • E.g.: To prepare 100 ml of 70% alcohol: 70 ml absolute alcohol plus 30 ml distilled water.

 

Preparation of 5% Phenol

• Melt 5 g of phenol by heating it.
• Dissolve in 100 ml distilled water.

Video : Preparation of TB Lab Disinfectants

Resources

• Tuberculosis Laboratory Biosafety Manual