Mycobacterial culture remains the gold standard for the diagnosis of active tuberculosis. However, an appropriate digestion and decontamination method is essential for the effective recovery of tubercle bacilli in culture. The study was designed to compare the efficacy of sputum treated with power ultrasound (PU) and routine NALC-NaOH methods for mycobacterial culture from clinically suspected cases of pulmonary tuberculosis. To evaluate the PU and routine NALC-NaOH methods, sputum specimens (n = 597) were studied (culturing on MGIT 960), and the performances were compared. Of the 597 samples, 89 (14.91%) sputum samples treated with the NaOH-NALC method were mycobacterial culture positive, including Mycobacterium tuberculosis (M.TB; n = 77, 12.90%) and nontuberculous mycobacteria (NTM; n = 12, 2.01%). One hundred and ten (18.43%) sputum samples treated with the PU method were culture positive, including M.TB (n = 87, 14.57%) and NTM (n = 23, 3.85%). The PU method detected 10 additional cases of M.TB and 11 additional cases of NTM when compared to the NALC-NaOH method. Statistical analysis showed that a significant difference was found in the culture-positive ratio of M.TB and NTM between the two method groups (p < 0.05). Compared with that of the NALC-NaOH method (8.04%), sputum treated with PU method (4.86%) had a significantly lower contamination rate (p < 0.05). In conclusion, our data indicate that, compared with the NALC-NaOH method, the PU method is a rapid and effective approach for mycobacterial culture when detecting active TB. However, its accurate mechanism has not been well addressed, and further investigation is still required.

Stool samples have been reported to be useful for the diagnosis of pulmonary tuberculosis (PTB), especially in patients who are unable to produce sputum. However, contamination limits the usefulness of stool specimens in mycobacterial culture. In this study, a novel decontamination method of power ultrasound (PU) was evaluated for mycobacterial isolation from suspected PTB cases. Stool samples (n = 650) were collected, and each sample was divided into approximately three equal groups. In addition to an AFB smear (Auramine O method), the stool samples were treated using different decontamination methods (NaOH-NALC vs. PU methods). The sensitivity (calculated against CRS) and contamination rates between the two methods were compared using McNemar’s test. Of the 650 samples, 32 (4.92%) stool samples treated with the NaOH-NALC method were culture-positive, including Mycobacterium tuberculosis (M.TB; n = 21, 3.23%) and nontuberculous mycobacteria (NTM; n = 11, 1.69%). Sixty-one (9.38%) stool samples treated with the PU method were culture-positive, including M.TB (n = 37, 5.69%) and NTM (n = 24, 3.69%). Statistical analysis showed that a significant difference was found in the isolation rate of M.TB and NTM between the two methods (p < 0.05). Additionally, compared with the NALC-NaOH method (19.07%), stool samples treated with the PU method (13.23%) had a significantly lower contamination rate (p < 0.05). In conclusion, our findings suggest that the utilization of the PU method as a novel decontamination technique could significantly enhance the isolation rates of both NTM and M.TB when stool specimens are employed for culture. Compared to the NaOH-NALC method, this approach proves to be more effective in facilitating stool mycobacterial culture.

Stool specimen is commonly used for mycobacterial culture to provide critical microbiological evidence for diagnosing tuberculosis (TB) in pediatric patients, especially when obtaining sputum specimens is challenging. However, the utilization of stool specimens for mycobacterial culture continues to face significant challenges in clinical practice, mainly owing to the relatively low diagnostic sensitivity and the frequent contamination by intestinal flora during specimen processing. This study evaluated the effectiveness of power ultrasound (PU) method in improving the recovery of Mycobacterium tuberculosis (M. TB) from stool specimens collected from children suspected of pulmonary tuberculosis (PTB). A total of 252 stool specimens were collected, and each specimen was subsequently divided into approximately three equal groups. One stool specimen was subjected to direct acid-fast bacilli (AFB) smear microscopy, while the other two stool specimens were processed using different decontamination methods(NaOH-NALC method vs. PU method). Out of the 252 specimens, positive cultures were observed in 14 (5.56%) stool specimens treated with the NaOH-NALC method, including M. TB (n = 11, 4.37%) and non-tuberculous mycobacteria (NTM; n = 3, 1.19%). Similarly, among the stool specimens subjected to the PU method, culture positivity was found in 36 (14.28%), comprising of M. TB (n = 24, 9.52%) and NTM (n = 12, 4.76%). The statistical analysis revealed a significant difference in the isolation rate of M. TB and NTM between the two methods (P<0.001). Furthermore, the contamination rate of stool treated with the PU method (14.28%) is significantly lower than that of the NALC-NaOH method (22.62%). In conclusion, our findings indicate that the PU method is a rapid and effective decontamination method for stool in children, improving the detection of active TB among pediatric populations when compared to the NALC-NaOH method.