Cartridge-based nucleic acid amplification test useful for early diagnosis of extrapulmonary tuberculosis
According to a study published in JAPI, Journal of the Association of Physicians of India, researchers have concluded that a Cartridge-based nucleic acid amplification test can rapidly diagnose highly infectious diseases like MTB within 2 hours. It is vital to initiate the treatment fast to prevent the development of resistant cases.
This study entitled “Diagnostic Approach to Extrapulmonary Tuberculosis by Cartridge-based Nucleic Acid Amplification Test” is led by Saswati Chattopadhyay and colleagues.
The team said tuberculosis (TB) is a highly infectious disease affecting millions worldwide. Pulmonary TB is the most common. Extrapulmonary cases are also very rampant and are responsible for a huge number of cases. It is challenging to diagnose extrapulmonary cases because of varied manifestations and infections paucibacillary nature.
Cartridge-based nucleic acid amplification test (CBNAAT) is simple and rapid.
The main aim of this study was to establish the usefulness of CBNAAT in diagnosing EPTB cases early.
For eight months, the team conducted a comparative study at a rural tertiary care hospital in West Bengal, India. The samples collected from different sites were pleural fluid, lymph nodes, cerebrospinal fluid (CSF), pus, ascitic fluid, and tissue aspirate. They were subjected to both CBNAAT and smear staining and examination under a fluorescent microscope. Positive samples were cultured, examined, and compared.
The key results of this study are:
- From 593 samples collected from different sites in suspected cases of EPTB—52 samples were positive by CBNAAT.
- Six cases demonstrated rifampicin resistance (RIF resistant).
- Smear staining of the samples by auramine-rhodamine stains and examined under the fluorescent microscope for acid-fast bacilli identifying 33 samples; the rest were negative.
- Lowenstein–Jensen media was used to culture Slides showing acid-fast bacilli.
They said CBNAAT is a very useful assay for diagnosing extrapulmonary cases early. It accurately identifies false negative samples by smear microscopy.
Our study found that EPTB cases are more in females than males.
The only limitation of the study was “more detailed study for over one year was not done.” they noted
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