Is Your Daily Shower Blasting Your Face With Pathogenic Germs?

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Main Category: Infectious Diseases / Bacteria / Viruses
Also Included In: Water - Air Quality / Agriculture;  Respiratory / Asthma
Article Date: 15 Sep 2009 - 9:00 PDT

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Most of us have a daily shower to keep us clean, not to infect our faces with potentially pathogenic bacteria. According to a study carried out by scientists at the University of Colorado at Boulder, USA, 30% of showerheads harbor significant levels of Mycobacterium avium (M avium), a bacterium associated with lung disease that can pose serious health risks for people with weakened immune systems, and can sometimes infect healthy people too.

The study, led by Professor Norman Pace, analyzed about 50 showerheads from nine US cities, including New York, Denver and Chicago. Pace said it is not surprising to find pathogens in municipal waters (a pathogen is an organism that can cause disease, such as a bacterium or virus). However, the scientists found that some M avium and other pathogens were accumulated in slimy biofilms that stuck to the inside of showerheads at over 100 times the background levels of municipal water. "If you are getting a face full of water when you first turn your shower on, that means you are probably getting a particularly high load of Mycobacterium avium, which may not be too healthy," he said.

You can read about this study in Proceedings of the National Academy of Sciences. The study was part of a larger one which aimed to assess the microbiology of indoor environments and was supported by the Alfred P. Sloan Foundation.

According to research carried out at The National Jewish Hospital, Denver, Colorado, USA, the increase in lung infections (pulmonary infections) in the USA over the last twenty or so years from non-tuberculosis mycobacteria species, such as M avium may be linked to a rise in the number of showers people have been taking in comparison to baths, Pace said.

Water spraying out of showerheads can spread pathogen-filled droplets that float around in the air and are inhaled by humans into the deepest parts of the lungs.

Symptoms of pulmonary disease caused by M avium include:

• Fatigue (tiredness)
• Persistent, dry cough
• Breathlessness (panting, shortness of breath)
• Weakness
• General feeling of malaise (feeling generally unwell)

People with weakened immune systems are more susceptible to develop these symptoms when exposed to M avium.

Pace added that although researchers have tried cell culturing to detect showerhead pathogens, the technique cannot detect 99.9% of bacteria species present in any given environment. A technique developed by Pace in the 1990s, using molecular genetics, allows scientists to swab samples directly from the showerheads, isolate DNA, amplify it using the polymerase chain reaction (PCR), and determine the sequences of genes present so as to identify specific pathogen types (types of disease-causing organisms).

Pace said "There have been some precedents for concern regarding pathogens and showerheads. But until this study we did not know just how much concern."

Initially, this study tested showerheads in small cities and towns, where many showers were using well-water instead of municipal water. "We were starting to conclude that pathogen levels we detected in the showerheads were pretty boring. Then we worked up the New York data and saw a lot of M. avium. It completely reinvigorated the study."

The scientists also broke several showerheads into tiny pieces, coated them with gold, used a fluorescent dye to stain the surfaces and used a scanning electron microscope to view the surfaces in detail. "Once we started analyzing the big metropolitan data, it suddenly became a huge story to us," said team member Leah Feazel.

A showerhead from Denver with high loads of M gordonae, a pathogen, was cleaned with a bleach solution. Several months later tests showed the bleach solution had caused a three-fold increase in M gordonae - this indicates resistance to chlorine by M gordonae.

Studies that had been carried out previously by Pace and team found enormous enrichments of M avium in soap scum, which is commonly found on vinyl shower curtains and floating on the water surface of warm therapy pools. A therapy pool study carried out by Pace and team showed that significantly high levels of M avium in the indoor pool environment were associated with lifeguard lung - a pneumonia-like pulmonary condition in pool attendants. This study led Pace and team into the showerhead study.

Asked whether it is dangerous to take showers, Pace answered "Probably not, if your immune system is not compromised in some way. But it's like anything else - there is a risk associated with it."

Pace added that as metal showerheads to not "load up" with so many pathogen-enriched biofilms, compared to plastic ones, metal showerheads may be a good alternative.

"There are lessons to be learned here in terms of how we handle and monitor water. Water monitoring in this country is frankly archaic. The tools now exist to monitor it far more accurately and far less expensively that what is routinely being done today," said Pace.

"Opportunistic pathogens enriched in showerhead biofilms"
Leah M. Feazel, Laura K. Baumgartner, Kristen L. Peterson, Daniel N. Frank, J. Kirk Harris and Norman R. Pace
Proceedings of the National Academy of Sciences, September 14, 2009, doi: 10.1073/pnas.0908446106

Written by Christian Nordqvist
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