Developing a method to detect lipoarabinomannan in pleural fluid and assessing its diagnostic efficacy for tuberculous pleural effusion

Advancements in LAM-based diagnostic kit for tuberculosis detection: enhancing TB diagnosis in HIV-negative individuals

Objective

The purpose of this study was to investigate the diagnostic value of urine lipoarabinomannan (LAM) detection based on chemiluminescence assay for pulmonary tuberculosis (PTB) and extrapulmonary tuberculosis (EPTB) in HIV-negative individuals.

Methods

A total of 215 patients and 37 healthy individuals were included according to inclusion and exclusion criteria, including 173 cases of PTB and 42 cases of EPTB. Sputum smears, sputum culture, TB-RNA, GeneXpert, and urine LAM results were obtained from all patients before treatment. Using the composite reference standard as the reference, the diagnostic performance of these methods for PTB and EPTB was evaluated, and the diagnostic performance and cost-effectiveness of different combinations were analyzed.

Results

In PTB, LAM exhibited the highest sensitivity (55.49%), followed by GeneXpert (44.51%). In EPTB, LAM also had the highest sensitivity (40.48%), followed by GeneXpert (33.33%). When combined with one method, LAM combined with GeneXpert showed the highest sensitivity for both PTB (68.79%) and EPTB (61.9%). When combined with two methods, culture, GeneXpert, and LAM showed the highest sensitivity for both PTB (73.99%) and EPTB (69.05%). In terms of cost-effectiveness analysis, the price of LAM was significantly lower than that of GeneXpert ($129.82 vs. $275.79 in PTB and 275.79 vs. 502.33 in EPTB). Among all combinations, the combination of LAM and sputum smear had the lowest cost, with prices of $124.94 for PTB and $263.72 for EPTB.

Conclusion

Urine LAM detection based on chemiluminescence assay can be used as an adjunct diagnostic tool for PTB and EPTB in HIV-negative individuals. This facilitates expanding the current application of urine LAM from solely HIV-positive populations to the general population. LAM detection can overcome the limitations of obtaining clinical samples, and its ease of sample acquisition will be beneficial for its broader application in a larger scope. For economically better-off areas, we recommend using a combination of LAM + GeneXpert+culture for higher sensitivity; for economically disadvantaged areas, LAM + smear microscopy combination can provide a quick and accurate diagnosis of tuberculosis at a lower cost.

Breakthrough of chemiluminescence-based LAM urine test beyond HIV-positive individuals: Clinical diagnostic value of pulmonary tuberculosis in the general population

To investigate the diagnostic value of a novel high-sensitivity urine lipoarabinomannan (LAM) test (chemiluminescence-based) for active tuberculosis in the general population. A retrospective study was conducted on 250 clinical suspected tuberculosis patients who were HIV-negative and visited the Fourth People's Hospital of Foshan from January 2022 to December 2022. Among them, there were 135 cases of pulmonary tuberculosis, 34 cases of extrapulmonary tuberculosis, and 81 cases of non-tuberculosis. Urine samples were collected for LAM antigen detection before treatment, and laboratory data of sputum smear acid-fast staining (smear method), sputum culture, and GeneXpert method were collected. Using clinical diagnosis as the reference standard, the diagnostic efficacy of 4 methods for detecting active tuberculosis was evaluated. For the 135 cases of pulmonary tuberculosis, the sensitivity of sputum smears, sputm culture, sputm GeneXpert method, and urine LAM were 29.6% (40/135), 45.9% (62/135), 59.3% (80/135), and 51.9% (70/135), respectively. The combination of LAM + GeneXpert and LAM + culture had the highest sensitivity for detecting active pulmonary tuberculosis, which were 71.0% and 78.2%, respectively. For the detection of sputum culture-negative pulmonary tuberculosis, the positive rates of smear, GeneXpert, and LAM were 0.0% (0/73), 53.4% (39/73), and 52.1% (38/73), respectively. LAM + smear and LAM + Genexpert could detect 52.1% and 68.5% of sputum culture-negative patients, respectively. The high-sensitivity urine LAM test holds promise for tuberculosis diagnosis in the general population. It demonstrates high-sensitivity, enabling the detection of sputum culture-negative pulmonary tuberculosis patients. Furthermore, when combined with existing methods, it can enhance the overall detection rate.