Atmospheric growth requirements for Alloiococcus species and related gram-positive cocci.

The growth of Alloiococcus otitis under different atmospheres and nutritional conditions was studied. The growth rates of 25 strains of gram-positive cocci representing five genera on heart infusion agar plates containing 5% rabbit blood and on brucella agar plates with and without sheep blood under aerobic, increased CO2, and anaerobic atmospheres were compared. Eight strains of alloiococci plated on heart infusion agar with rabbit blood and on brucella sheep blood agar grew under aerobic and candle jar atmospheres. Two of these strains showed poor anaerobic growth after 7 days. Strains of Aerococcus viridans, Aerococcus urinae, Helcococci kunzi, Dolosigranulum pigrum, Gemella haemolysans, and Gemella morbillorum grew well under all three atmospheres and on the three types of media and in thioglycolate broth. These results confirm all the aerobic atmospheric requirements for Alloiococcus strains and show that aerobic growth characteristics help distinguish the alloiococci from the other gram-positive cocci that are facultatively anaerobic.