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. pyogenes also has the potential to produce outbreaks of disease in younger children in daycare. Rheumatic fever is most frequently observed in the age group most susceptible to group A streptococcal infections (ie, children aged 5-15 y).