Abstract:
Tuberculosis continues to pose a significant danger to human health, and current TB diagnostic techniques are not up to standard. Sputum, the most commonly used specimen for pulmonary tuberculosis diagnosis, is hazardous, challenging to manage, and frequently in short supply among TB patients. Therefore, invasive techniques such as bronchoscopy are used for obtaining high-quality sputum samples from HIV patients and children. Nucleic acid amplification tests are regarded more sensitive than sputum culture for detecting TB. The aim of this study, therefore, was to evaluate the reliability of Polymerase chain reaction of mouthwashes as an alternative sample compared to sputum culture for diagnosis of pulmonary tuberculosis. A sum of 300 individuals with suspected pulmonary TB were included for assessment. Novel reagents were used to homogenize fresh mouthwashes collected through gargling with normal saline, and DNA was extracted via the phenol-chloroform method. The sputum counterparts were decontaminated using a solution of N-acetyl cysteine, (NAlc-NaOH) technique and grown on Lowenstein - Jensen medium to isolate M. tuberculosis. The cultures were kept at 37 °C and checked for growth every week for a minimum of 8 weeks with the findings being documented. PCR targeting the secA1 gene from the mouthwashes was conducted between January 2016 to December 2018. and the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV of the PCR technique compared to that of sputum culture. PCR had an accuracy, sensitivity, specificity, PPV, and NPV of 129%, 100%, 65%, 67.6%, and 100% respectively. The extreme test accuracy may have been influenced by sample rejection in the laboratory, similar to the sensitivity. A substantial number of participants had false positive results as indicated by low specificity. The low PPV indicated that a positive test result was likely wrong. However, the high NPV indicated that no one with the negative test had the disease. Mouthwashes are an alternate specimen for sputum-based molecular diagnosis for MTB. The procedure is less invasive, easier, and non-aerosol producing efficient alternate approach with significant impact on clinical management and control of TB. More attention should be given to sample collection, and technique optimization to improve disease laboratory diagnostic accuracy using mouthwashes.
