Tap water is essentially harmless. Yet it's teeming with microorganisms - up to 100,000 per milliliter. It's when people have health conditions or clinical procedures that compromise their ability to defend against these microorganisms that healthcare-acquired pneumonia, or a bloodstream (septicemia) or wound infection can result. Here's what you need to know to lower the risk of infection from waterborne pathogens in your facility.

Microorganisms in water systems
Many microorganisms are found in the water systems of hospitals; they include bacteria (Legionella pneumophila, Stenotrophomonas maltophilia, Pseudomonas aeruginosa,), fungi (Aspergillus species, Fusarium species) and amoebae (Hartmanella, Naegleria, Acanthamoeba). Microorganisms in water improve their chances of survival by attaching to and multiplying in biofilm (slime that lines pipes and fixtures), as well as living inside other microbes. Those living inside amoebae can survive contact with chemical disinfectants and other harsh environmental conditions. Such amoeba-resisting microorganisms include Legionella pneumophila (the causative agent of Legionnaires' disease), Mycobacterium avium and Pseudomonas aeruginosa.1

Tap water can transmit infection when it's used simply for drinking or, more seriously, for rinsing such things as medical equipment and contaminated medication vials. Patients can be exposed through bathing (whirlpools), showering, drinking, or direct contact with contaminated medical equipment (water baths) or bath toys.2,3 An interesting development has been the recognition that water systems are a source of infection by fungi (Aspergillus and Fusarium species), which have long been associated with airborne spread.2

Who's at risk for infections?
The microorganisms found in water aren't generally pathogenic for healthy individuals, but they may be for the immunocompromised patient, which could result in significant morbidity and mortality. In fact, mortality due to waterborne Pseudomonas aeruginosa pneumonia was recently estimated at 1,400 cases per year.2,4 The mortality for healthcare-acquired Legionnaires' disease is estimated to be about 40 percent, which is twice as high as cases of community-acquired Legionnaires' disease.5 The conditions associated with increased risk of acquiring an infection from a waterborne pathogen include patients with hematological malignancy, immunosuppression (treatment with high dose steroids, chemotherapy), transplantation and burns. Most of these patients will have outpatient surgery, if needed, in the hospital setting. Young patients (primarily neonates) are also at increased risk of infection after exposure to waterborne microorganisms.

Prevention of waterborne infections
Many of the measures that effectively prevent healthcare-acquired Legionnaires' disease are also effective in preventing exposure to other waterborne pathogens. Although water treatment methods are effective in reducing Legionella within a water system and decreasing the risk of infection, it's difficult to achieve "no detectable organisms" throughout a complex water system as prescribed for transplant units by the Centers for Disease Control and Prevention.8 Here are five ways to prevent waterborne infections:

• Reduce patients' exposure to tap water. This is inexpensive and potentially effective. Give them distilled water (either bottled or boiled for three minutes) to drink, and don't rinse in tap water objects that they'll come into contact with. Adopting alcohol-based rubs for hand hygiene (thus decreasing hand-washing in tap water) might also help.
• Elevate the chlorine or heat. Temporarily elevate either the chlorine level or the hot water temperature, followed by flushing water outlets. This involves either having your maintenance professional add chlorine, or raising the temperature on your hot water heater to 60?C or higher. These measures are temporary and require you to flush the water outlets - run all taps for at least 30 seconds before use after you've implemented these measures.
• Treat the hot water system. Continually treat the hot water system with copper and silver ions. Work with a water-maintenance professional to achieve this.
• Use ultraviolet light units. These systems, which are attached at the point of use, cost anywhere from several hundred to a thousand dollars each.
• Add filters to taps. At the Veterans Administration Hospital in Pittsburgh, we recently evaluated a disinfection option that may be able to achieve the CDC's no-detectable-organisms goal for transplant units: a point-of-use filter you can attach to faucets or showers.9 We found that the Aqua-safe filters eliminated Legionella pneumophila and Mycobacterium species from tap water, and reduced the total bacterial concentration by more than 99.9 percent.

Patient-safety factor
Ultimately, you may need a combination of methods to prevent healthcare-acquired infections due to waterborne pathogens.6,7 But making the effort to make your water supply safer is integral to ensuring a safe environment for all patients - especially those whose immune systems are compromised for any reason.

References:
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2. Anaissie EJ, Penzak SR, Dignani C. The hospital water supply as a source of nosocomial infections: A plea for action. Arch Intern Med 2002; 162:1483-1492.
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5. Stout JE, Yu VL. Hospital-acquired Legionnaires" disease: new developments. Curr Opin Infect Dis 2003; 16(4):337-341.
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7. Stout JE, Yu VL. Experiences of the first 16 hospitals using copper-silver ionization for Legionella control: implications for the evaluation of other disinfection modalities. Infect Control Hosp Epidemiol 2003; 24:563-568.
8. Centers for Disease Control and Prevention. Guidelines for Preventing Opportunistic Infections in Among Hematopoietic Stem Cell Transplant Recipients. Morb Mort Wkly Rep 2000; 49((RR10)):1-128.
9. Sheffer P, Stout JE. Efficacy of new point-of-use water filters to prevent exposure to Legionella and waterborne bacteria. 31st Annual Meeting of the Association for Professionals in Infection Control , 87. 2004. Ref Type: Abstract
10. Muscarella LF. Contribution of tap water and environmental surfaces to nosocomial transmission of antibiotic-resistant Pseudomonas aeruginosa. Infect Cont Hosp Epidemiol 2004; 25(4):342-345.
11. Denton M, Todd NJ, Kerr KG, Hawkey PM, Littlewood JM. Molecular epidemiology of Stenotrophomonas maltophilia isolated from clinical specimens from patients with cystic fibrosis and associated environmental samples. Journal of Clinical Microbiology 1998; 36(7):1953-1958.
12. Tobin-D"Angelo M, Blass MA, del Rio C, Halvosa J.S., Blumberg HM, Horsburgh CRJr. Hospital water as a source of Mycobacterium avium complex isolates in respiratory specimens. Journal of Infectious Diseases 2004; 189:98-104.