Dataset of nontuberculous mycobacteria (NTM) images on Elite agar medium
Description
This is an image dataset of non-tuberculous mycobacteria (NTM) isolated from heater cooler units (HCUs) using the recently developed NTM Elite agar medium (bioMérieux, Marcy-l’Étoile, France). Non-tuberculous mycobacteria (NTM) are waterborne pathogens commonly found in building water systems where they are a primary concern to vulnerable patient populations and can cause severe disease. NTM Elite agar is a highly selective medium that includes four antimicrobial agents. Samples were concentrated through 0.45 µm mixed cellulose esters filters and filters were directly placed on the medium. Starting from the seventh day, cultures were examined weekly for seven weeks. Images of colonies confirmed as NTM were captured using an iPhone 11 dual camera. The collection of the image dataset was done in laboratory, at day-light and at different day of growing. Images represent the top view of NTM Elite agar plate. All images are encoded in the standard JPG format and each image is named with an alphanumeric label whose first 4 letters define the species of the Mycobacterium, the number indicates the isolation number, followed by the day on which the photo was taken. For example, the label “MCHE1_4gg” indicates that the species in the photo is Mycobacterium chelonae, that is the isolation number 1 for this species and the photo was taken on day 4 of the incubation period. The list of mycobacteria species abbreviations is listed in Table 1. To maintain an organized structure, the dataset is divided into two main sections: ORIGINAL and AUGMENTED. The first main folder “ORIGINAL” contains the original images within ten subfolders, corresponding to the different species of NTM isolated, for a total of 92 images. The second main folder “AUGMENTED” contains the augmented images, also divided into ten subfolders. We performed some types of augmentation techniques such as hue (between −5° and +10°), saturation (between −10 % and +10 %), brightness (between −10 % and +10 %) and exposure adjustments (between −5 % and +5 %), to diversify and enrich the dataset, simulating also lighting changes. The folders “Mycobacterium gordonae” and “Mycobacterium paragordonae” contain images of mycobacteria colonies that have a very similar appearance. These species are closely related; in fact the phylogenetic tree based on the 16S rRNA gene sequences of these two species shows a 99.0% similarity: it is therefore understandable that they are almost indistinguishable. The images in the folder “More than one mycobacterial species” present more than one type of colonies of Mycobacteria per plate: arrows of different colors indicate colonies belonging to different species. Inside this folder an excel file, named “arrows and species” lists the correspondence between the colors of the arrows and the species for each image. In the repository, there is also an Excel file that contains the list of images along with information related to the strain and the day of growth.