Regensburg has a central train station (HBF) with regular bus connection to the University. Please check the Deutsche Bahn website for schedules and fares. After leaving the terminal building through the main entrance, go 200 m straight to "Albertstraße" and take Bus line 6 or 11 to University Hospital. The closest bus stop to the meeting venue is called "Universitaet Mensa". Tickets can be bought from the driver or vending machines.
Please find a scheme about the inner city bus routing here.