Observations suggesting the development of streptococci from pleomorphic filamentous gram negative bacteria.

In the course of studying a freshly isolated strain of Mycoplasma laidlawii, a single small bacterial colony developed on a plate among the mycoplasma colonies. It attracted attention as the mycoplasma grew to large satellite colonies around it. In transplants made from the bacterial colony, tiny colonies developed, consisting of thin Gram negative rods and filaments which soon became pleomorphic and autolyzed. This organism was designated 1GN. On a plate inoculated with this organism, a large white micro-coccus colony developed, probably as a contaminant from the air. Around the coccus colony large satellite colonies developed, but most of these did not contain the Gram negative organisms or mycoplasma. They consisted of Gram positive streptococci varying considerably in morphology in different colonies. This paper contains the description of this observation and studies resulting from it. Since the 1GN was in many respects similar to filamentous Gram negative bacteria usually present in the human throat, studies were made with such organisms to explore whether some of these would produce phenomena similar to that observed accidentally. No connection was apparent between the mycoplasma and the 1GN. MATERIALS AND METHODS The bacterial strains studied were: The Gram negative bacterium (1GN) indicated in the introduction, and in addition, eighteen strains of Gram negative filamentous bacteria isolated from the human throat. The plates from which these strains were isolated were received from the routine bacteriology laboratory of the hospital, and were marked to contain Hemophilus hemolyticus. These strains are designated as H.H., but no attempt was made to check their classification. All strains were isolated by us and studied immediately after isolation. The air coccus that produced satellite growth in the culture of lGN consisted of medium-sized uniform round cocci which stained strongly Gram positive. These cultures were different from the Gram positive pleomorphic organisms that developed in the cultures of the Gram negative bacteria and no pleomorphism or alteration of