Non-specific sensitization to old tuberculin: Cultural studies

Abstract

Three hundred and fifty-seven strains of acidfast bacteria isolated from a variety of human, animal and environmental sources were isolated at the Queensland Institute of Medical Research (QIMR) and were studied in comparison with 137 strains isolated from patients with lung disease and with 47 stock strains. Of the Q.I.M.R. strains, 43 were identified as Myco. fortuitum , five as Myco phlei , and 20 as Nocardia spp., but the remaining 289 were ‘anonymous’. The patient strains included three Myco. tuberculosis , 13 Myco. fortuitum , four Nocardia spp., and 117 were ‘anonymous’. The unnamed strains could be divided into four groups on the basis of colony size, pigmentation and growth time under controlled conditions. These four types are briefly described as the large chromogens (19 strains), large mucoid chromogens (13), the ‘Battey’-like strains (132), and the small chromogens (242). All the strains were tested for growth at various temperatures, resistance to streptomycin, isoniazid, diamino-diphenyl-sulphone, and acetic acid, effect of light on pigmentation, growth in thioglycollate medium, sodium chloride broth and on various liquid and solid media, including Littman's, catalase reaction, tyrosine clearing and paraffin utilization. In light, some Myco. fortuitum strains turned black, some strains of other acid-fast bacteria became orange, and many strains developed a more intense pigmentation. Myco. fortuitum , ‘Battey’-like and small chromogen strains grew on Littman's medium and were usually resistant to drugs and acetic acid, whereas the other acid-fast bacteria usually failed to grow and were sensitive. Significant observations were growth of all the Myco. phlei strains and one Nocardia strain at 52° C., but none of the others; the heavy growth of the rapid-growers in thioglycollate broth, usually with pellicle formation; the production of an intense white discoloration on charcoal egg yolk agar by Myco. phlei ; the clearing of tyrosine crystals by some Nocardia strains but by no mycobacteria; the strong catalase activity of fast growing strains. There were no obvious differences in the properties of strains derived from patients and the environment. It seems likely that patients become infected from the environment.