Workplace-related complaints due to exposure to contaminated humidifier water - hypersensitivity pneumonitis with antibodies to Verticillium lecanii

We present a case report of a patient with hypersensitivity pneumonitis due to exposure to contaminated humidifier water and another four patients wit h related complaints. The setting was a building with photographic laborato ries and corresponding office rooms that were supported with air by a humid ification, ventilation and air conditioning (HVAC) system. In the humidifie r water, we found different fungi and bacteria, in particular the microorga nisms Verticillium lecanii (2,1 x 10(2) cfu/ml), Stenotrophomonas maltophil ia (3,7 x 10(3) cfu/ml), and Pseudomonas fluorescens (3,6 x 10(3) cfu/ml). The patient with hypersensitivity pneumonitis revealed precipitating antibo dies against Verticillium lecanii (ELISA). The role of the bacterial contam ination is not dear, the possible role of lipopolysaccharides (endotoxins) is discussed. The case report emphasizes the importance of careful maintena nce and control of HVAC systems.