Researchers from the University of Colorado sampled what they call biofilm from 45 germy showerheads in nine U.S. cities, including New York City, and eight others in Colorado, North Dakota, Illinois, and Tennessee. They analyzed the ribosomal RNA gene sequences from the swab samples to figure out exactly what microorgamisms lurked there. They compared them with swabs from water before it entered the showerhead.
“What we show is the showerhead biofilm contains Mycobacterium avium concentrations relative to other organisms 100-fold higher than in water before it comes out of the shower head,” says Norman R. Pace, the study’s senior author and distinguished professor of molecular, cellular and developmental biology at the University of Colorado, Boulder.
The study is part of a larger effort the team is involved in, focusing on the microbiology of the indoor environment and how it may contribute to illness. The current study received funding from the National Institute of Occupational Safety and Health and the Alfred P. Sloan Foundation.
“We don’t know a whole lot about Mycobacterium avium prevalence. It’s hard to detect and largely ignored.”
Researchers do know that infections caused by the Mycobacterium avium complex occur often in patients with conditions that hamper cellular immunity such as AIDS and in patients who have chronic lung disease such as emphysema, according to the Infectious Diseases Society of America.
But the infections are not reported nationally to the CDC, whose researchers suspect the infections are probably environmentally acquired.