Wikipedia
The Jesuati (Jesuates) were a religious order founded by Giovanni Colombini of Siena in 1360. The order was initially called Clerici apostolici Sancti Hieronymi (Apostolic Clerics of Saint Jerome) because of a special veneration for St. Jerome and the apostolic life the founders led. Colombini had been a prosperous merchant and a senator in his native city, but, coming under ecstatic religious influences, abandoned secular affairs and his wife and daughter (after making provision for them), and with a friend of like temperament, Francesco Miani, gave himself to a life of apostolic poverty, penitential discipline, hospital service and public preaching.
The name Jesuati was given to Colombini and his disciples from the habit of calling loudly on the name of Jesus at the beginning and end of their ecstatic sermons. The senate banished Colombini from Siena for "imparting foolish ideas to the young men of the city", and he continued his mission in Arezzo and other places, only to be honourably recalled home on the outbreak of the bubonic plague. Howard Eves writes that the order was then "dedicated to nursing and burying the victims of the rampant bubonic plague."
He went out to meet Urban V on his return from Avignon to Rome in 1367, and craved his sanction for the new order and a distinctive habit. Before this was granted Colombini had to clear the movement of a suspicion that it was connected with the heretical sect of Fraticelli, and he died on July 31, 1367, soon after the papal approval had been given. The guidance of the new order, whose members (all lay brothers) gave themselves entirely to works of mercy, devolved upon Miani.