Abstract
A number of acidfast organisms has been observed in this laboratory during the last year. As far as could be ascertained by a search of the literature, they have not been described. They fall into 3 distinctly different groups.
Group I. The organisms in this group are air contaminators. These colonies, on various agars, are round, transparent or creamy white, with a diameter of 0.01-1.0 mm. All strains show constantly smooth colonies, with the exception of one which is constantly rough. On smears they are diphtheroid-like, very pleomorphic rods and cocci. The rods are frequently granulated, beaded, barred or clubbed. The cocci vary in size from barely visible granules to coccoidal or diplococcoidal forms of the size of staphylococci. Frequently large single cocci are seen. With the Ziehl-Neelsen method only a part of each smear retains the carbolfuchsin. The relative proportion of the acidfast elements varies greatly with the different strains and with the age of the cultures. Acidfastness is enhanced by growth on egg media. Growth occurs within 24 hours on the usual agar media, in the usual broth media and on tubercle bacilli media; but the addition of dyes, commonly used for the cultivation of tubercle bacilli (gentian violet, malachite green) inhibits growth. In broth, growth occurs throughout, either by even clouding, or slightly granular. All smooth strains are poor fermenters, forming acid but no gas in dextrose only, or not at all. The rough strain ferments several sugars and liquifies gelatine. All strains are completely avirulent for guinea pigs and rabbits, even in massive and repeated doses.
Group II. This group consists of 6 strains, isolated from human material (sputum or urine) or from known strains of human tubercle bacilli.
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