Identification in solid culture by inverted phase microscopy and Ziehl-Neelsen stain

With the aim of identifying morphological differences in colonies of different species of mycobacteria by means of inverted phase microscopy, nine species of high-prevalence pathogenic mycobacteria were seeded in 7H11 solid medium and were observed for up to 21 days. Additionally, Ziehl-Neelsen (ZN) stains were carried out for each one of them. No morphological variations were identified among the species grown on solid medium; however, it was identified that all are able to form cords in solid medium in an early stage of growth, being corroborated by the Ziehl-Neelsen stain in Mycobacterium tuberculosis. so techniques based on detecting M. tuberculosis depending on the identification of the cords should be taken with caution so as not to generate a bad diagnosis, so microbiological characteristics could also be established as a minimum time to detect growth, temperature of growth and bacillary characteristics based on the Ziehl-Neelsen stain for each species studied.