Led by Washington University in St. Louis and involving the University of Colorado at Boulder and San Diego State University, the new study assessed the microbe population in a warm hospital therapy pool through a ribosomal RNA analysis that involved cloning and sequencing genes. The team concluded that the microbes, many of them pathogenic, were enriched just inches above the pool's surface by as much as 60 percent.
The microbes included "Mycobacterium avium," which can cause "lifeguard lung" and which was present in nine ill lifeguards who worked at the facility.
The technique used in the study is 1,000 times more sensitive than standard microbe-culturing techniques used at most indoor pool facilities today, the researchers said. The two-year study involved a molecular survey of a common RNA gene found in all life forms, eventually matching some cloned and sequenced bacteria to the "Mycobacterium avium" bacterium present in pool attendants ill with hypersensitivity pneumonitis, a lung condition that mimics pneumonia symptoms.
The study was published in the March 14 issue of the Proceedings of the National Academy of Sciences. The paper was authored by Lars Angenent of Washington University; Norman Pace, Mark Hernandez and Allison Amand of CU-Boulder; and Scott Kelley of San Diego State University.
The findings were somewhat surprising," said Pace, a professor of molecular, cellular and developmental biology at CU-Boulder. "People should be very aware of the risks in using indoor pools or hot tubs."
Washington University's Angenent, a former postdoctoral researcher at CU-Boulder, said the high presence of aerosol pathogens poses the greatest concern for very young childr