Evaluation of two pretreatment methods for the detection of Mycobacterium tuberculosis in suspected pulmonary tuberculosis

Abstract

The objective of the current study was to compare the efficacy of phenol ammonium sulphate (PhAS) and sodium hypochlorite (NaOCl) pretreatment methods for the direct microscopy with the Löwenstein‐Jensen (LJ) culture to detect acid fast bacilli (AFB) from pulmonary tuberculosis suspected cases using sputum specimens. To evaluate PhAS and NaOCl methods, sputum specimens (n = 1145) were studied and the performance of each method was compared with LJ media. The, PhAS centrifuged smear and NaOCl centrifuged smear method demonstrated higher sensitivity (71.47% and 77%), specificity (99.61% and 98%), positive predictive value (98.8% and 94.88%) and negative predictive value (88.35% and 90.25%), respectively, when compared to LJ culture. However, the direct AFB smears and PhAS centrifugation method was ineffective to detect few Mycobacterium tuberculosis cases from sputum specimens, particularly in blood tinged specimens with scanty bacilli. Interestingly, NaOCl method could efficiently detect the Mycobacterium tuberculosis cases from blood tinged sputum specimens with scanty bacilli. The current study concluded that NaOCl method could be the most efficient and sensitive method than direct AFB smear and PhAS centrifuged smear method for the direct detection of AFB in suspected cases of pulmonary tuberculosis.

Pancreatin-Cetyl Pyridinium Chloride Digestion and Decontamination Method; A Novel, Sensitive, Cost-Effective Method for Culturing Mycobacterium tuberculosis

“…This microscopic technique revealed a diagnostic accuracy of 60.4% (sensitivity) and 99.77% (specificity), respectively. It was consistent with previous studies wherein the diagnostic accuracy for the LED FM ranged between 65-85% and 80-90%, respectively [19,20]. Further, direct LED microscopy detected one smear-positive but culture-negative case after treatment with the NALC-NaOH method.…”

Long‐Term Storage at −80°C: Effect on Rate of Recovery of Mycobacterium tuberculosis From Direct Acid‐Fast Bacilli Smear‐Positive Sputum Samples

“…For the rapid detection of tubercle bacilli, the global TB control program uses direct microscopic examination of sputum specimens . Unfortunately, the direct microscopy (DM) has low sensitivity when compared to culture . Culture is considered as the gold standard method for diagnosis of TB .…”

A handheld orbital mixer for processing viscous samples in low resource settings

“…27 Mixing beads in these viscous specimens is a known challenge, 33 and typically requires a pre-treatment step before analysis. 34,35 Our results show that biomarker capture is indeed slower in more viscous uids (Fig. 4), but that it does approach the same equilibrium amount of bound protein.…”