Streptococcus pyogenes is a microorganism of the bacteria kingdom considered to be a unique and extremely complex opportunistic pathogen. The bacteria is particularly unique because it has the ability to cause several illnesses, ranging from mild to severe. Streptococcus pyogenes is named so because strepto means chains, coccus is used to describe a spherical shape, and pyogenes is used to describe a pus-producing organism. “S. pyogenes is considered one of the most common pathogens in humans and can be found on the skin or in the respiratory tract of 5 to 15% of the population, without causing disease” (Todar, 2002 ). Although the bacteria is often carried asymptomatically by many people, it can potentially cause life-threatening invasive diseases in cases where it reaches deep tissues, such as streptococcal toxic shock syndrome and necrotizing fasciitis type II. also known as Strep Toxic Shock Syndrome and Necrotizing Fasciitis Type II, also known as Strep Toxic Shock Syndrome and Necrotizing Fasciitis Type II, also known as Eating Illness. Invasive streptococcal infections also include joint or bone infections, destructive wound infections, myositis, meningitis and endocarditis (Todar, 2002). Non-invasive forms include pharyngitis (strep throat), scarlet fever, cellulitis, and impetigo (superficial skin infection also known as pyoderma). Since noninvasive forms are common, predictable, and fairly easy to treat, this article will discuss rare, invasive, and often fatal forms of disease caused by S. pyogenes, particularly necrotizing fasciitis. Causal agents. pyogenes is a Gram-positive, non-motile, non-sporulating cocci that exists in chains or pairs of cells (Todar, 2002) and is negative for oxidase and catalase (Khan, 2013). Individual cells are round to ovoid in shape and measure 0.6 to 1.0 micrometers in diameter. S. pyones is an aerotolerant anaer...... middle of paper ......erica, 12(2), 181-186.Sharkawy A, Low DE, Saginur R, et al. Serious group A streptococcal soft tissue infections in Ontario: 1992-1996. CID 2002; 34:454-60. Steer AC, Lamagni T, Curtis N, Carapetis JR. (2012) Invasive group of streptococcal disease: epidemiology, pathogenesis and management. Drugs. 2012;72(9):1213-27. http://dx.doi.org/10.2165/11634180-000000000-00000. PMid:22686614.Todar, Ken. 2002. “Streptococcus pyogenes” Tortora G, Funke B, Case C. 2007. Microbiology: an introduction, 9th edition. Pearson Education, Inc. Trent, J. Kirsner, R. (2002). Necrotizing fasciitis wounds. http://www.medscape.com/viewarticle/444061_4 Wong CH, Chang HC, Pasupathy S, Khin LW, Tan JL, Low CO. Necrotizing fasciitis; clinical presentation, microbiology and determinants of mortality. J Bone Joint Am 2003; 85 – One:1454