<i>Serratia marcescens</i> (IMAGE) Trinity College Dublin Caption Colonies of Serratia marcescens, one of the bacteria species used in the study, growing on an agar plate. This common bacterium is sometimes responsible for causing hospital-acquired infections in humans. Credit Deirdre McClean Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.