Bacterial lung infection. Light micrograph of a section through lung tissue in actinomycosis. This is an infection by an Actinomyces sp. bacterium, forming these bacterial colonies (solid pink, centre). Actinomyces bacteria occur in the mouths of healthy people, and are often found in tooth abscesses. Other abscesses are also found in the lungs and abdomen. Treatment uses antibiotic drugs like penicillin. Magnification unknown.