UK doctors have highlighted potential problems with the breathing system filters used in anesthesia, including intensive care units, after demonstrating that they don’t provide protection from harmful bacteria and yeast when they become wet. A new study shows that when they were wet, six commonly available filters allowed substantial passage of Candida albicans (a yeast infection linked to a range of chronic illnesses) and coagulase-negative staphylococci (a common hospital-acquired bacterial infection).