Gram-Staining of Enterococcus hirae

This Gram-staining of a sputum from the "Atlas of Bacteriology" (E. & S. Liningstone, Ltd., Edinburgh, 1947) shows two chains of four and five cells, respectively, of Gram-positive Enterococcus hirae (formerly called Streptococcus faecalis or faecium). Also present are Gram-negative Haemophilus influenza (the plentiful small rods) and Diplococcus catarrhalis (the pairs in the upper right) as well as some yeast cells.

E. hirae is a facultative anaeorobe. It has a simple metabolism and can generate ATP only by glycolysis. This bacterium has therefore been used for bioenergetic studies for over 30 years.