Swimming with the mycobacteria

The patients were working out in a hospital's warm therapeutic pool in Boulder, Colorado, when Mark Hernandez walked in and dipped sterile bottles in the water.

Cathryn Delude
Jun 5, 2005

The patients were working out in a hospital's warm therapeutic pool in Boulder, Colorado, when Mark Hernandez walked in and dipped sterile bottles in the water. He also set up a liquid impinger, a device that suctions air from above the pool and entrains the particulates, including microorganisms, in sterile buffered water. The swimmers, seemingly unperturbed, continued their physical therapy.

The hospital had called Hernandez, an environmental engineer at the University of Colorado, Boulder, who specializes in water disinfection systems, to solve a worrisome problem. Several pool workers had become sick with persistent respiratory afflictions often caused by Mycobacterium avium. But their monitoring and lab tests hadn't detected these bacteria in the water.

What Hernandez found back at the lab, however, might have given pause to the swimmers watching him set up. Under the microscope, the pool water was found to be loaded with 10 to 100 times more...