Editor 2013 Streptococci are Gram-positive bacteria capable of causing a wide spectrum of diseases in humans and animals. Group A streptococci (Streptococcus pyogenes) are exclusively human pathogenic bacteria. Group C and group G streptococci, which were traditionally considered as animal pathogenic bacteria, are emerging as causative organisms of human diseases. The diseases caused by streptococci range from self-limiting manifestations such as pharyngitis or impetigo to lifethreatening diseases such as necrotizing fasciitis and streptococcal toxic shock syndrome.