Evaluation of Environmental Mycobacteria Contamination in a Specific Pathogen Free Animal Facility from a Tropical Country

• Published in: Zoonoses and public health 2010-09, Vol.57 (6), p.382-387
• Main Authors: Frantz, F.G, Andrade, L.N, Araújo, R, Araújo, J.I, Faccioli, L.H, Sato, D.N
• Format: Article
• Language: English
• Subjects: Acetylcysteine; Animal facility; animal housing; animal pathogenic bacteria; Animals; Antigens, Bacterial; Bacilli; Bacteria; bacterial contamination; BCG Vaccine - immunology; Biofouling; Brazil; Contamination; Decontamination - methods; Environmental Exposure - analysis; environmental mycobacteria; Environmental testing; Housing, Animal; Laboratory animals; Mice; microbial detection; Mycobacterium; Mycobacterium - immunology; Mycobacterium - isolation & purification; Mycobacterium bovis BCG; Mycobacterium Infections - immunology; Mycobacterium Infections - microbiology; Sodium Hydroxide; Specific Pathogen-Free Organisms; Tuberculosis; Tuberculosis - immunology; Tuberculosis - prevention & control; Vaccines
• ISSN: 1863-1959; 1863-2378
• DOI: 10.1111/j.1863-2378.2009.01241.x

With the evidence showing the protection variability of bacille Calmette-Guérin, new potential vaccines for tuberculosis have been tested around the world. One of the general concerns in tuberculosis vaccine development is the possibility of priming the host immune system with prior exposure to environmental mycobacteria antigens, which can change the efficacy of subsequent vaccination. As there is a great homology between the species from Mycobacterium genera, the previous contact of experimental animals with environmental mycobacteria could sensitize the mice and, in this way, could influence subsequent vaccine research. The aim of our study was to investigate critical points in an animal facility to search for environmental mycobacteria that eventually could be in direct or indirect contact with the experimental animals. Samples were collected from surfaces of walls, floor, animal cages and shelves and analysed using the Ogawa-Kudoh decontamination method. Samples of drinking water, food and sawdust were collected for analysis by the NALC/NaOH decontamination method. Also, the samples were cultivated directly in broth medium, without any method for decontamination. After decontamination methods, we observed bacterial colony growth in 4.31% of the total of samples analysed. These samples were stained with Ziehl-Neelsen and we did not detect any acid-fast bacilli, suggesting that the animal facility analysed is free from contamination by environmental mycobacteria and is not a source of mycobacterial antigens. Furthermore, our study showed a new paradigm in tuberculosis vaccine development: concern about the animal facility environment in terms of immune system priming of experimental animals by nascent bacterial contaminants.