Branhamella catarrhalis. Coloured Scanning Elect- ron Micrograph (SEM) of Branhamella catarrhalis bacteria, cause of ear and nose infections. These Gram- negative, green-coloured spherical bacteria are usually found in pairs and hence referred to as diplococci. Here they are seen alongside three red blood cells. B. catarrhalis is associated with low-grade infections of the lower respiratory tract and occasionally with acute infections of the middle ear (otitis media) in immune deficient patients. Treatment is with antibiotics. Magnification: x5,000 at 6x6cm size.