Aerococcus, a New Bacterial Genus

Abstract

SUMMARY:The generic name Aerococcus is proposed for a group of aerobic Grampositive 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 composition: 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 streptococci 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. We consider that this organism has sufficient points of difference from both streptococci and staphylococci to justify its being placed in a new genus for which we propose the name Aerococcus. DESCRIPTION O F AEROCOCCUS Cultural and morphological characteristicsAfter 18-24 hr. incubation at 37" on blood agar the colonies of Aerococcus are 0.5-2.0 mm. in diameter, semi-transparent, white or grey, and surrounded by a wide or narrow zone of greening (Pl. 1, fig. 1); with some strains the centre of the area of greening may be very dark. The organisms grow well on nutrient agar with or without 0.5y0 glucose, and on serum agar, chocolate agar and blood agar, The colonies are larger on blood agar than on the other media; the addition of serum or glucose to nutrient agar results in only slight increase in colony size. Growth is not enhanced, and may be slightly decreased, by incubation anaerobically or in air with 30% carbon dioxide. The green discoloration round colonies on blood agar or chocolate agar is much decreased in depth and area when the cultures are incubated anaerobically. On all these media growth takes place at 22", the colonies taking about 42 hr. to reach the size reached in 18 hr. a t 37". There is no growth on potato. In nutrient broth or peptone water growth is very poor, but it is considerably increased by the addition of 0.5 yo glucose.Microscopically the organisms are round Gram-positive cocci 1-2 p. in

The Bacterial Flora of the Air of Occupied Rooms

“…It is important to distinguish mouth streptococci both from faecal streptococci, which make up an average of 20 % of the total streptococcal count, and from the aerococci which are generally more common than streptococci, and from which they can be distinguished only by microscopy or biochemical tests (Williams et al 1953). Neither enterococci nor aerococci are found in the mouth, so that their presence in the air cannot be regarded as indicative of respiratory pollution.…”

“…The term 'micrococci' is used for all Gram-positive cocci that are not streptococci, coagulase-positive staphylococci, nor aerococci. The last-named is a Grampositive coccus, not a streptococcus, distinguished from the micrococci chiefly by its ability to grow in the presence of 1:500,000 crystal violet, and to produce greening of blood agar (Williams, Hirch & Cowan, 1953). Micrococci predominated over all other types, and although no formal classification of the micrococci was attempted it was obvious that a great many colonial varieties were present.…”

Clinical and microbiological features of infective endocarditis caused by aerococci

“…Aerococcus viridans was the first aerococcal species to be identified but is a rare cause of human infections [2,11]. The most common site of isolation for both A. urinae and A. sanguinicola is human urine [3,12,13,14,15,16].…”

Aerococcus sanguicola sp. nov., isolated from a human clinical source.

“…Initially, the genus contained a single species, Aerococcus viridans (Williams et al, 1953). Aerococcus viridans occurs in a wide range of habitats (e.g.…”

“…The genus Aerococcus was created by Williams et al (1953) to accommodate some Gram-positive, microaerophilic, catalase-negative organisms that were clearly distinguishable from streptococci. Initially, the genus contained a single species, Aerococcus viridans (Williams et al, 1953).…”