NAAT

Nucleic acid amplification tests (NAATs) detect microorganisms by amplifying targeted nucleic acid sequences to detectable levels. They can target DNA or RNA and are widely used in infectious disease diagnosis and monitoring. The most common NAAT is the polymerase chain reaction (PCR), including real-time PCR (qPCR). For RNA pathogens, reverse transcription is coupled to amplification (RT-PCR). Isothermal NAATs that operate at a constant temperature include loop-mediated amplification (LAMP), NASBA, RPA, and TMA.

Specimen processing typically involves collection and extraction and purification of nucleic acids, followed by amplification and detection. Detection methods include real-time fluorescence, end-point readouts, turbidity, or lateral flow readouts in integrated assays.

In clinical practice, NAATs are used for rapid, sensitive detection of bacteria, viruses and some parasites. They are standard for diagnosing SARS-CoV-2 infection, Chlamydia trachomatis, Neisseria gonorrhoeae, Mycobacterium tuberculosis and other infections, as well as for HIV viral load and other viral diagnostics. They also support genotyping, resistance testing and public health surveillance.

Advantages include high analytical sensitivity and specificity and the ability to detect nonviable organisms. Limitations include the need for specialized equipment and skilled personnel, higher cost, risk of contamination and inhibitors, and potential false negatives due to sample quality or genetic targets changing. Regulatory status varies by jurisdiction and assay type, with many NAATs subject to clinical laboratory validation and regulatory clearance in many countries.