Susanna was born in 1955 in Milan, Lombardy, the most industrialised region in Italy. She is the youngest of four sisters in a family committed to progressive values and causes during the 1970s season of protests and mass demonstrations to improve social and labour rights. As a national leader of the FIOM metalworkers union she followed the automotive and steel industries. In 1997 she was elected General Secretary of FLAI-CGIL, the food and agriculture union of Lombardy region. Three years later she became the first woman to be elected General Secretary of CGIL of Lombardy, which is the largest regional organisation of CGIL, with a membership of over one million. In 2008 she moved to Rome as a National Secretary and in 2010 she also became the first woman to be elected General Secretary of CGIL with a majority of over 80 per cent. She was then re-elected in 2014 for a second term. Since January 2019 she is head of Gender and International policies at CGIL. CGIL is the largest national trade union centre in Italy, with a membership of over 5.5 million.