Aerococcus, a New Bacterial Genus

SUMMARY: The generic name Aerococcus is proposed for a group of aerobic Gram-positive cocci that are commonly found in the air of occupied places and in dust. The most characteristic features of the organisms are ability to grow in the presence of 40 yo bile and to produce greening on blood agar. They are catalase-negative, and do not show chain-formation in culture. For the collection and recognition of mouth streptococci from air a selective culture medium was devised (Williams & Hirch, 1950) which had the composi-tion: serum agar, 100 ml.; sucrose, 5 g.; potassium tellurite, 1.0 mg.; crystal violet, 0.25 mg. This selective medium inhibits the growth of diphtheroid and coliform organisms and practically all strains of those Gram-positive cocci that would ordinarily be regarded as staphylococci. It permits good growth of most streptococci, including Streptococcus pyogenes, viridans-type strepto-cocci and enterococci. However, in air samples from occupied rooms, about 70 yo of the colonies are not of typical streptococci, but are of a Gram-positive coccus that does not appear to have been adequately described in the literature