Bacteria Isolated from Dust (IMAGE) Northwestern University Caption This photo shows a disc diffusion test, where each disc contains a different antibiotic. The discs covered in growing bacteria contain bacteria that are resistant to antibiotics. Credit Taylor Brown/Northwestern University 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.