Abstract
There is a need for rapid, practical and accurate tuberculosis diagnostic tools that are adapted to resource-poor settings in order to ensure that those affected receive proper and timely treatment. Light-Emitting-Diode microscopy (LED) has recently been endorsed by the WHO for diagnosis of TB in these countries. A much recent smear diagnosis method, PREVI Fluo TB by using LED microscopy, has been made available. However, due to the novelty of the method, there is no information available on the specificity and sensitivity when compared to established methods such as the ordinary LED-Auramine O or the classical widely used Ziehl- Neelsen (ZN) in TB positive persons. This study was undertaken to compare the sensitivity, specificity, positive predictive value and negative predictive value of PREVI Fluo TB stain with ZN method and Auramine O-LED microscopy taking culture as reference. A prospective cross sectional study was conducted in St. Paul’s Hospital Millennium Medical College, Addis Ababa, Ethiopia. Spot- Morning-Spot sputum samples from 248 TB suspected study participants were collected. The smear detection rate of PREVI Fluo TB, ZN, Auramine O and culture were found to be 35 (14.1%), 24(9.7%), 44(17.7%) and 30(12.1%) respectively. The sensitivity of the PREVI Fluo TB method was 76.67%, better than ZN and slightly less than Auramine O which were 59.07% and 78.13% respectively. Nevertheless, the specificity (94.5%) was lower than ZN (96.79%) and higher than Auramine O (91.2%). The negative likelihood ratio of PREVI Fluo TB, ZN, and Auramine O methods were 0.25, 0.45, and 0.24 respectively. The PREVI Fluo TB method had a PPV of 65.71% which is higher than the Auramine O (56.82%) but with a comparable NPV (96.71% and 96.57% respectively). The respective agreements of the ZN, Auramine O and PREVI Fluo TB methods with the gold standard were K=0.585, K=0.621 and K=0.664. There was a substantial agreement of PREVI Fluo TB result with ZN (k=0.636) and Auramine O methods (K=0.745).Given the practical benefits of PREVI Fluo TB for TB diagnosis, and comparable accuracy to the current standard of Auramine O fluorescence method and the gold standard culture, PREVI Fluo TB should be considered by TB diagnostic laboratories, as an alternative diagnostic tool for conventional Auramine O fluorescent stain.
Highlights
Tuberculosis (TB) is one of the oldest known human diseases and it is still one of the major causes of mortality and a major public health problem in low-income countries
Sensitivity, specificity, positive and negative predictive values and likelihood ratios were calculated by using OpenEpi Version 2.3 for the PREVI Fluo Light emitting diode (LED), Auramine O LED and conventional ZN microscopy using mycobacterial culture as the reference standard
Laboratory investigation of every collected sputum samples of the study participants were done by the three methods and confirmed with the forth gold standard method TB culture
Summary
Tuberculosis (TB) is one of the oldest known human diseases and it is still one of the major causes of mortality and a major public health problem in low-income countries. Diagnosis is often based on a test for “acid-fast” bacteria in a sputum smear (made by smearing sputum on a microscope slide). In patients with active pulmonary TB, only an estimated 45% of infections are detected by sputum microscopy [2]. This test (Ziehl-Neelsen) has the advantage of being simple but is hampered by very low sensitivity; it may only detect half of all cases with active infection. It is very dependent on the skill of the technician [3]. Besides being labour-intensive, direct sputum smear microscopy may have considerable patient costs and inconvenience associated with the need to submit multiple sputum specimens over a period of up to three days [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
