Mycobacteria in semi-public swimming-pools and whirlpools.

The presence, densities and species distribution of atypical mycobacteria were assayed in samples from swimming-pools in semi-public areas (hotels, recreational parks and camping grounds) and from whirlpools (in sauna institutes, fitness clubs and recreational parks). Tap water used to supply these pools was also investigated. Mycobacteria were frequently detected in all types of samples, the numbers in whirlpools on the average being about ten times higher than those in swimming-pools and tap water. Mycobacterium gordonae was the predominant species in all samples. Special attention was given to the possible presence of opportunistic pathogenic mycobacteria. M. marinum was not detected in any of the samples; M. kansasii was recovered 3 times from whirlpools only. M. avium and the M. fortuitum-M. chelonei complex were found in both types of pool samples but in highest densities in whirlpools. Mycobacterial densities exhibited a significantly negative association with the concentration of hypochlorous acid-1.0 mg/l being required to assure low levels in the bathing water. There was also a negative association with redox potential but positive associations with total aerobic colony count at 37 degrees C, ammonium and total Kjeldahl nitrogen (in swimming-pools only). No association was found with temperature, potassium permanganate consumption, total coliforms, Pseudomonas aeruginosa or Staphylococcus aureus.