Age of Menarche. Menarche marks the commencement of the reproductive phase of a woman's life. Records suggest that there was a secular decline in the average age at menarche in developed countries across the 19th and 20th Centuries until the 1950s, with an average age at menarche of 15-17 years reported in the mid-19th Century.
CHARACTERISTICS: Streptococcus pyogenes is an aerobic, gram-positive extracellular bacterium. It is made up of non-motile, non-sporing cocci that are less then 2 Âµm in length and that form chains and large colonies greater then 0.5 mm in size.HARACTERISTICS: Streptococcus pyogenes is an aerobic, gram-positive extracellular bacterium. It is made up of non-motile, non-sporing cocci that are less then 2 Âµm in length and that form chains and large colonies greater then 0.5 mm in size.
Background. Infection with Streptococcus pyogenes, a beta-hemolytic bacterium that belongs to Lancefield serogroup A, also known as the group A streptococci (GAS), causes a wide variety of diseases in humans.n addition to infections of the upper respiratory tract and the skin, S pyogenes can cause a wide variety of invasive systemic infections. Along with Staphylococcus aureus, group A streptococcus is one of the most common pathogens responsible for cellulitis.