Quantitative analyses of mycobacteria in a dolphinarium

Introduction
When occupational or environmental skin infections due to mycobacteria appear, the sources are rarely investigated. In this survey we wanted to quantify the levels of mycobacteria in a dolphinarium with a history of skin infections, among the staff and the dolphins, associated with mycobacteria.

Methods
In total, 10 water samples were taken from different parts of the pool and water treatment system in order to detect mycobacteria and to be able to evaluate the function of the water treatment system. One sample was also taken from the thawing of fish, given as food to the dolphins, since this was a potential source of mycobacteria into the facility. The samples were analyzed using a combination of two routine techniques used in clinical microbiological laboratories.

Results
Mycobacteria were detected in 6 of 11 samples. None of the samples taken in the pools, where dolphins and staff swim, had detectable levels of mycobacteria. Detectable levels of M. arupense was found in all 6 samples (20-500 CFU/L) from the water treatment system, M. marinum was found in 3 samples (32-200 CFU/L) and M. fortuitum was found in one sample (100 CFU/L). M. marinum and M. arupense were also found in the thawing water from the fish but the concentrations could not be determined.

Discussion
Detectable levels of mycobacteria could only be found in the water treatment system of the dolphinarium. There were low levels of mycobacteria in water compared to what have been measured earlier in whirlpools with the same analytical method. The results indicate that the present water treatment system is sufficient to reduce the levels of mycobacteria in the parts of the facility where dolphins and staff swim. The technical staff must however be cautious during maintenance work in the water treatment system to prevent occupational skin infections.