Evaluation of the performance of led fluorescent microscopy in diagnosis of tuberculosis

Aim: The aim of the Project is to compare of the results of LED fluorescent microscopy (LED FM) and Erlich Ziehl Nelseen (EZN) staining in the examination of the respiratory specimens and to evaluate the performance of LED fluorescent microscopy with culture. Materials and Methods: In the study, the respiratory specimens obtained from patients prediagnosed with pulmonary tuberculosis were examined in the Tuberculosis Laboratory of Manisa Celal Bayar University Hafsa Sultan Hospital between February 2018 and November 2019. Two smears from each specimen processed with NALC-NaOH method were prepared and they were evaluated both EZN and LED FM by blind readers. The results of culture were used as reference for determination of the performance of LED FM. Results: In the study 1499 respiratory specimens were evaluated with LED FM. Mycobacteria were grown in the culture of 134 specimens (8.9%). When the culture was accepted as reference method, the sensitivity, specificity, positive predictive value and negative predictive value of LED FM were found as 64.2%, 96%, 61.4% and 96.5%, respectively. However scarce positive-culture negative results (54/1365) with LED FM were obtained significantly higher than the results with EZN (0/1365). The reason of this was thought to be due to the lack of the experience of the readers. The reading time of LED FM was 69% time saving. While the costs of LED fluorescent microscopes are high, the cost of fluorescent stains found to be cheaper than the EZN staining method. The consistency between the readers was found to be good and it was determined that LED FM could be preferred in routine examination as a result of the survey conducted to the readers. Conclusions: The sensitivity of LED FM was found 12.7% higher than the sensitivity of EZN. However, because of the high rate of false positive results, the introduction of LED-FM should be accompanied by appropriate training of the readers. It is also thought that the use of LED FM will be cost-effective in large-scale laboratories in our country.