Light-microscopic morphology, ultrastructure, culture, and relationship to disease of the nutritional and cell-wall-deficient alpha-hemolytic streptococci.

alpha-Hemolytic streptococci, variously described as cell-wall deficient (C), L form (L), thiol dependent (O), satelliting (S), pyridoxal dependent (PY), and nutritionally deficient (N), or CLOSPYN, were isolated from patients with endocarditis, brain abscess, subauricular abscess, septicemia, acute and chronic urethritis, recurrent aphthous stomatitis, and fever of undetermined origin. With the aid of satelliting, most of the strains were adapted to grow on a human Mycoplasma growth agar consisting of brain-heart infusion agar fortified with 20% human blood, yeast extract, and arginine. Selected CLOSPYN strains required extensive subculture for only partial reversion to parentallike characteristics. Four of six strains biochemically tested were judged Streptococcus morbillorum. Two were unidentifiable. The CLOSPYN form was relatively inert biochemically, but glucose was converted mainly to lactic acid, with acetic acid also present. Guanine-cytosine values were 39%-43%. Cell wall material was present by transmission electron microscopy (TEM), but its synthesis was uneven on single cells and abnormally thickened on other cells. Closely spaced, incompleted septa occurred in cell chains, which resulted in unusually long chains of flattened cells resembling on TEM a stack of checkers. Mesosomes were frequent, greatly enlarged, convoluted, and elongated. They were often sectioned as circular and laminated, with 2-5 layers. Mesosomes were in close contact with nucleoid bodies, which, in turn, were closely apposed or integral with the cytoplasmic membranes in areas of cross-wall development. Chaotic morphology typifies the group. The inclusion of urinary tract infections is new in the gamut of diseases caused by CLOSPYN streptococci.