Ziehl-neelsen stain in the pathology lab, performance and diagnostic aid in bronchoalveolar lavage

Abstract

Introduction: With more than 100 years of use, the Ziehl-Neelsen stain is still current used worldwide Objective: To compare the performance of the diagnostic test use to demonstrate mycobacteria in the clinic and pathology lab, in bronchoalveolar lavage samples Materials and methods: We retrospectively review 737 bronchoalveolar lavage samples from 2019 to 2020 in the San Vicente Fundación hospital (Medellín – Colombia), comparing the performance of three test done in parallel, mycobacteria PCR, culture and the Ziehl-Neelsen stain, the latter done in the pathology lab. Results: 93/737 patients were classified as sick, due the positivity in any of the three test. Culture, PCR and the Ziehl-Neelsen stain had a sensibility of 0.80, 0.76 y 0.51, respectively. However, only 5/75 (6.5%) of the positive cultures, had a positive results within the first four weeks and the rest in eight weeks. The combined PCR test and Ziehl-Neelsen stain in parallel, improved the sensibility of the PCR test alone from 0.76 a 0.88, change that was statistically significant (p = 0.022). Conclusion: At least in bronchoalveolar lavage samples, culture is still the test with better sensibility. The use in parallel of the PCR test and the Ziehl-Neelsen stain improved in a statistically significant manner the PCR test perform alone, nevertheless the higher turnaround time of the Ziehl-Neelsen stain.