General Information: Source of the antibiotic erythromycin. Saccharopolyspora erythraea is the soil bacterium that produces the industrially important antibiotic erythromycin A. Erythromycin is a clinically important and potent macrolide antibiotic. It is used to treat infections caused by several prokaryotic pathogens such as Streptococcus, Staphylococcus, Mycoplasma, Ureaplasma, Chlamydia and Legionella. Production of this antibiotic is lower than others in the same class, such as penicillin or cephalosporin, which has led to the development of a genetic system to attempt to enhance the production of erythromycin.