Strep A

Beta-hemolytic group A streptococcus (S. pyogenes) is the most common bacterial agent associated with upper respiratory tract infections in humans. The most commonly occurring group A streptococcal disease is pharyngitis. Males and females are equally affected by group A streptococcus. Seasonal increases in the prevalence of group A streptococcus occur. Streptococcal pharyngitis is most prevalent in winter and early spring with the higher incidence of disease occurring in crowded populations such as school children. A severe form of streptococcal infection causes streptococcal toxic shock syndrome (STSS) which is associated with invasive soft tissue infections and the early onset of shock and organ failure. Invasive group A streptococcal infection and STSS have increased the cause of morbidity and mortality among children and adults. Early diagnosis and treatment of group A streptococcal pharyngitis has been shown to reduce the severity of symptoms and further complications such as rheumatic fever and glomerulonephritis. The conventional methods used for identification of group A streptococci depend on the isolation and identification of the organism on blood agar plates. These methods usually require 18-24 hours of incubation at 37 °C. This delay in identifying group A streptococcus often caused physicians to administer therapy without first knowing the etiological agent. With the development of immunologic tests capable of detecting group A streptococcal antigen directly from throat swabs rapid test results can now be achieved for better patient treatment.