GLI GLI Quality Tool
GLI Quality Tool — Version 2.0

Writing a Procedure for TB Rapid Test Kit Lot Validation

Rapid molecular diagnostic platforms such as Xpert MTB/RIF Ultra, Truenat, and line probe assays have reshaped frontline tuberculosis detection, and Australian laboratories rely on these assays every day to support clinicians in Sydney, Melbourne, Brisbane, Perth, and Adelaide. Before any new shipment of cartridges or reagents is released into routine service, the laboratory must confirm that the lot performs to the manufacturer's claims and to the laboratory's own expectations. Lot validation is therefore a foundational exercise that protects patients, satisfies accreditors, and reduces the risk of false negatives or false positives slipping into clinical reporting.

A well-written procedure brings consistency to this exercise. It guides scientists, medical laboratory technicians, and quality officers through each decision point, from receiving the consignment to signing off the final report. For Australian facilities, the document must also align with the requirements of the National Pathology Accreditation Advisory Council (NPAAC), the National Association of Testing Authorities (NATA), and the Therapeutic Goods Administration (TGA), all of which recognise lot validation as a non-negotiable part of a quality management system.

Understanding Lot Validation in the Australian Context

Australian TB epidemiology sits in stark contrast to many regional neighbours. The overall notification rate hovers around six cases per 100,000 people, yet rates are several times higher in Aboriginal and Torres Strait Islander communities and in migrants and refugees who have arrived from high-burden countries. This pattern shapes the workload of culture and molecular laboratories in metropolitan public health reference centres and in regional hubs such as Darwin and Cairns. Even with low overall numbers, laboratories must keep their rapid diagnostic workflows tight, because each missed case carries disproportionate community consequences.

Regulatory expectations reinforce the need for rigorous lot validation. The TGA regulates in vitro diagnostic medical devices under the Therapeutic Goods Act 1989, and any laboratory introducing a new kit or a new lot is expected to verify performance locally. NATA accreditation assessments routinely scrutinise the evidence behind each kit introduction, and NPAAC's Requirements for Medical Pathology Services explicitly call for verification of examination methods before they are used for patient testing. Documenting this verification through a dedicated procedure demonstrates that the laboratory takes its public health obligations seriously.

Documenting Acceptance Criteria and Performance Specifications

A useful procedure begins with a clear statement of what the lot must achieve. Acceptance criteria typically include limits of detection for Mycobacterium tuberculosis complex, agreement with a reference method such as MGIT culture or a previously validated PCR platform, and reproducibility across operators and instruments. For an Australian laboratory running GeneXpert or Abbott m2000 systems, it is wise to set numeric targets such as a percentage concordance with the previous lot and an acceptable coefficient of variation for cycle threshold values on a positive control.

The procedure should also distinguish between the manufacturer's performance claims, which appear in the Instructions for Use, and the laboratory's own verification targets. The TGA may have reviewed the kit for market authorisation, but it is the local laboratory that bears responsibility for confirming that performance in its own hands, with its own operators, and under its own environmental conditions. This distinction is worth recording explicitly in the procedure so that auditors in NATA assessments can see that the laboratory has thought through the verification rather than simply reproduced the manufacturer's brochure.

Sampling Strategy and Test Workflow Design

The next section of the procedure should describe how many samples, controls, and replicates will be tested. A common approach is to use a panel of archived specimens or spiked samples that includes at least ten to twenty positive samples covering a range of bacterial loads and a similar number of negative samples. Where archived material is scarce, the laboratory may supplement with contrived specimens or quality control material provided by the manufacturer, provided that the source is documented and traceable.

Workflow design needs to match the realities of an Australian laboratory's working day. Technicians in a Brisbane public health laboratory, for example, may process samples in batches between clinic pickups and afternoon courier runs. The procedure should specify the order of testing, who performs each step, where records are kept, and what happens if a test fails on first run. Including a simple decision tree or workflow diagram helps new staff orient themselves quickly, particularly in laboratories with rotating rosters or staff from culturally and linguistically diverse backgrounds who may benefit from visual instructions alongside written text.

Verifying Biosafety Practices During Lot Testing

Lot validation generates aerosols when preparing suspensions and loading cartridges, so biosafety cannot be an afterthought. The procedure should name the biological safety level required for each manipulation and reference the laboratory's broader biosafety manual. For many Australian laboratories this means PC3 containment, which aligns with the Department of Health and Aged Care's guidance on handling Mycobacterium tuberculosis. Operators must wear fitted respirators, work within a certified biosafety cabinet, and follow validated decontamination procedures for spills and waste.

Training records are equally important. Staff should be signed off as competent before they participate in lot validation activities, and refresher training should be scheduled at intervals that match the laboratory's risk assessment. A biosafety training guide tailored to TB work provides a useful template for documenting both initial training and ongoing competency assessments. Embedding a reference to this resource within the procedure helps auditors trace the laboratory's biosafety claims back to a controlled document.

Recording Results, Deviations, and Corrective Actions

Robust records are the backbone of any validation exercise. The procedure should specify the forms or electronic systems used to capture test results, instrument identification, reagent lot numbers, operator names, dates, and any deviations from the planned protocol. Many Australian laboratories now use middleware or laboratory information systems that can streamline data capture, but even paper-based records need a consistent template so that results can be retrieved during audits or incident reviews.

Deviations are inevitable, and the procedure should describe how they are handled. A failed control, an instrument error, or a temperature excursion in the cold chain should trigger a documented investigation. The laboratory may need to quarantine the consignment, notify the manufacturer, and report the issue to the TGA through the appropriate medical device vigilance pathway. Linking each deviation to a root cause analysis and a corrective action plan demonstrates continual improvement and feeds useful information into management review meetings.

Integrating Lot Validation into the Quality Management System

The procedure does not stand alone. It sits within a wider quality management system built around the twelve Quality Systems Essentials, and it interacts with documents covering equipment, purchasing, internal audit, and continual improvement. A useful integration step is to ensure that the validation report feeds into the laboratory's annual management review, where trends across multiple lots can be examined together. If a particular supplier consistently produces borderline lots, this evidence supports procurement decisions for the following year.

For laboratories just beginning their quality journey, starting with a single, well-written procedure for rapid diagnostic test kit lot validation is a practical way to build momentum. The Phase 1 resources of the GLI Quality Tool offer checklists that help a small team in regional Australia or a busy metropolitan laboratory decide what is essential and what can wait. As the document matures and the laboratory's confidence grows, it can be expanded to cover additional assays, including phenotypic drug susceptibility testing and next-generation sequencing workflows.

Essentials to Cover in Every Lot Validation Procedure

Practical Steps for a Smooth Verification Run

Ready to formalise your approach? Begin by mapping the steps you already perform against the GLI Quality Tool checklists, then turn the gaps into clearly worded paragraphs. Share the draft with your quality manager, your senior scientist, and at least one bench operator to catch blind spots early. Once approved, archive the procedure where new staff can find it on their first day, and set a reminder to review it after your next lot arrives so that lessons learned are woven back into the document.