Group A Streptococcus bacteria, scanning electron micrograph (SEM). Streptococcus (Strep) has 2 types - group A and group B. Group A strep causes strep throat, scarlet fever, impetigo, toxic shock syndrome, cellulitis, and necrotizing fasciitis. Group B strep can cause blood infections, pneumonia and meningitis in newborns. In adults, it can cause urinary tract infections, blood infections, skin infections and pneumonia. Cell division in streptococci occurs along a single axis, so as they grow, they tend to form pairs or chains. Magnification: x4000 when printed at 10cm wide.