Even Bacteria Have Baggage (IMAGE) PLOS Caption Yen and Papin showed cases where adaptation to one drug, followed by adaptation to a different drug, led to different final resistance levels of the two drugs compared to adaptation to the two drugs in the opposite order. Drug history-dependent effects in the adapted populations of bacteria led to observable differences both genetically (e.g., mutations) as well as phenotypically (e.g., resistance levels and pigment production). Credit Phillip Yen Usage Restrictions CC-BY 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.