Use of a serologically distinct strain of Thermoactinomyces vulgaris in the diagnosis of farmer's lung disease.

During investigations into farmer's lung disease it was noticed that Micropolyspora faeni (MF) was isolated and identified with ease, but difficulty was encountered in the identification of Thermoactinomyces vulgaris (TV), although an organism resembling TV was frequently isolated. Extracts prepared from the isolates resembling TV (called Thermoactinomyces vulgaris variant, TVV) when tested against the standard TV antiserum by double diffusion, did not produce any precipitin lines. When TVV extracts were tested against the serum of a patient from whom TVV had been isolated from the sputum, +++ precipitin lines were observed. With the TVV extracts the authors have demonstrated the existence of a serologically distinct strain of TV, and also that it would be a useful addition to the routine testing of antibodies to farmer's lung disease.