Controlling Legionella in Hospital Drinking Water: An Evidence-Based Review of Disinfection Methods
YUSEN LIN, JANET E. STOUT, VICTOR YUCAMBRIDGE UNIVERSITY PRESS, INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY, FEBRUARY 2011 IntroductionThis study reviewed the efficacy of different disinfection methods for controlling Legionella in hospitals, including copper-silver ionization, chlorine dioxide, hyperchlorination, monochloramine, UV, point-of-use filtration, and superheat-and-flush. The four criteria each disinfection method must meet to validate efficacy include: ResultsA summary of findings for each disinfection method is included below. Copper-silver ionization– Only method validated by the four criteria– Easy installation and maintenance– Not impacted by higher temperatures– Residual levels are maintained for a prolonged period– Efficacy declines in pH greater than 8.5 Chlorine dioxide– Penetrates biofilm– Effective over a wide range of pH levels– Creates harmful byproducts– Difficult to maintain residual levels Monochloramine– Penetrates biofilm– Effective over a wide range of pH levels– Can cause anemia in dialysis patients– On-site generation can be complicated Hyperchlorination– Most expensive and unreliable of all methods– Causes corrosion– Does not penetrate biofilm– Introduces carcinogens into the water Point-of-use filtration– Effective against Legionella and Mycobacterium– Provides immediate protection making them a good option for outbreaks– Not cost-effective for long-term use UV– Non-chemical– Works best when installed on the incoming water supply– Does not provide systemic disinfection Superheat-and-flush– Effective in emergencies– Not effective for prolonged use– Limited to hot water lines ConclusionThere are several viable methods for controlling Legionella, but copper-silver ionization was the only method validated by the four criteria at the time of this study. The researchers concluded that “copper-silver ionization appears to be the best available technology today for controlling Legionella colonization in hospital water systems.” They suggested that rigorous maintenance plans, regular monitoring of ion concentrations, and frequent Legionella testing are necessary to ensure long-term success. Full report
Intermittent Use of Copper-Silver Ionization for Legionella Control in Water Distribution Systems: A Potential Option in Buildings Housing Individuals at Low Risk of Infection
ZEMING LIU, JANET E. STOUT, MARCIE BOLDIN, JOHN RUGH, WARREN F. DIVEN, VICTOR L. YUOXFORD ACADEMIC, CLINICAL INFECTIOUS DISEASES, JANUARY 1998 IntroductionThis study evaluated three healthcare facilities colonized with Legionella to determine if: ResultsThe Legionella positivity rate (percentage of test sites positive for Legionella) was significantly reduced for the two test buildings using copper-silver ionization. Both test buildings remained Legionella-free for six to eight weeks after deactivating the copper-silver ionization system. The researchers found high concentrations of copper in the biofilm and suggested this to be the reason that early recolonization of Legionella was prevented. ConclusionBecause copper-silver ionization provides a residual effect of preventing early recolonization of Legionella, it is possible to rotate one copper-silver unit between several buildings. The study explained that this method could be considered for facilities that house individuals at low risk for contracting Legionnaires’ disease. Full study
Biofilm: America’s Newest Water Safety Challenge
The United States has some of the safest drinking water in the world. But its water supply is facing a new challenge — a slimy growth inside pipes that is encouraging outbreaks of illness responsible for over 7 million illnesses and 6,000 deaths every year. That’s the disturbing finding of a new analysis of waterborne disease from the US Centers for Disease Control and Prevention that was 10 years in the making. “It’s not just about ingestion of water anymore,” said study coauthor Vince Hill, chief of the CDC’s waterborne disease prevention branch. “We captured a more modern picture of what waterborne disease looks like in the United States today.” Biofilm, a glue-like mixture of bacteria, fungi, amoebas, and other microorganisms, is taking up residence inside some of the 6 million miles of plumbing that support drinking, sanitation, hygiene, cooling, and heating systems in US buildings, according to the report published Wednesday in the journal Emerging Infectious Diseases. “If you’ve ever felt that slimy film on your teeth when you haven’t brushed in a while, that’s a biofilm,” said lead author Sarah Collier, an analytic epidemiologist at the CDC. “Biofilms tend to form anywhere there are microbes and water.” Robust biofilms can provide a safe haven for microbes, protecting them from disinfectants in the water, Hill said. That’s how potentially deadly waterborne pathogens such as Legionella bacteria (which causes Legionnaires’ disease) grow and escape into the air, sickening and killing thousands each year. In fact, the report found over 90% of all deaths and the majority of hospitalizations from waterborne diseases are caused by just three airborne pathogens that prosper in biofilms. “It’s sort of a paradigm shift for us: ‘Oh my gosh, there are things growing inside these pipes,’ whether it’s inside the water utilities system or inside your home,” Hill said. “So that’s kind of the new frontier that we’re recognizing,” Collier added. “And we think this is an area where we can help prevent disease.” Over 3 billion in healthcare costs The CDC team estimated total illnesses, visits to emergency rooms, hospitalizations, deaths, and direct health care costs for 17 waterborne infectious diseases that can be found in the home and industrial plumbing, hot tubs, recreational pools, and water parks. It was the first report to examine disease from all water sources (drinking, recreational and environmental) and all exposure routes (ingestion, contact, and inhalation), Hill said. The analysis found that over 7 million waterborne illnesses occur each year, resulting in over 600,000 annual visits to emergency rooms, 118,000 hospitalizations, and 6,630 deaths — totaling $3.33 billion in direct health care costs. Otitis externa, more commonly known as swimmer’s ear, was the most common ailment, accounting for 4.7 million or 65% of annual waterborne illnesses and 20% of hospitalizations. Norovirus infections, which cause vomiting and diarrhea, were the second most common, with 1.3 million cases, followed by the diarrheal disease giardiasis with just over 400,000 annual cases. While much less frequent, biofilm-associated pathogens were responsible for the highest number of hospitalizations and deaths, costing the US healthcare system $2.39 billion annually. Nontuberculous mycobacteria disease causes lung, skin, and soft tissue infections that can be difficult to control. Also called NTM, it was the most deadly of the three, causing 51,400 hospitalizations (44%) and 3,800 deaths (57%) a year. Direct health care costs in the US from NTM were $1.53 billion annually. Legionella bacteria, responsible for outbreaks of the pneumonia-type illness called Legionnaires’ disease and a mild flu-like illness called Pontiac fever, caused 995 deaths (15%) each year, the report found. Pseudomonas pneumonia was responsible for 15,500 hospitalizations and 730 deaths each year, costing the US $453 million annually. People would come in contact with these airborne diseases through shower heads, building cooling towers, and decorative outdoor fountains, among other sources, the report said. The CDC team also tracked illnesses caused by the parasite cryptosporidium and the salmonella, shigella, vibrio, campylobacter, and Shiga toxin-producing E. coli bacteria, which all typically cause stomach cramps and bloody diarrhea. Because cryptosporidium is “extremely chlorine resistant” and highly infectious at low doses, it has emerged as the major cause of outbreaks associated with treated aquatic venues, the report said. An infrastructure challenge Efforts In the United States to improve water safety are “recognized as one of the greatest public health achievements of the 20th century,” the report said. Outbreaks of diseases caused by feces-infested drinking water, including cholera and typhoid, were common in the 19th and early 20th centuries but are long gone. “In the past 40 years, we’ve seen a significant decrease in waterborne disease but the complexities have increased with more building plumbing issues and more recreational water issues,” said J. Alan Roberson, executive director of the Association of State Drinking Water Administrators, who was not involved in the study. At the same time, funding has stayed flat or decreased for research, infrastructure, regulations, and the ability to increase compliance with the existing regulations, both at the federal and state levels, Roberson said. Then there is the issue of aging pipes and the challenges of private wells or unregulated water systems that serve an estimated 43 million persons. “Drinking water from the treatment plant to your water meter is really heavily regulated and a lot of work is put into making sure that it’s safe,” Collier said. “Once it’s in your house or in a building, however, it’s on the individual homeowner or the building owner to make sure it’s safe. “Consumers can do their part, Roberson said, by understanding their home plumbing system starting with where the water comes into their home, the materials that make up the plumbing, and how the water is distributed throughout the house. “While it’s not part of this report, the country has around 6 million lead service lines and the ownership of those service lines are typically split between the water system and the property owner,” Roberson said. “So removal of all of those lines is another public health initiative that’s going to require a collaborative effort across a large number of communities.” Steps to take
How Biofilm Affects Waterborne Pathogens
Biofilm is a collection of different types of bacteria, fungi, and protists in a colony enveloped in secreted slime that allows them to adhere to moist surfaces ideal for growth. Biofilm is one of the most common techniques for the growth and protection of these microorganisms and is not only a nuisance but a potential hazard. Bacterial resistance Bacteria in the biofilm can be up to a thousand times more resistant to typical disinfectants and antibiotics than the same microorganisms grown in suspension. Rapid recolonization Even if all free-floating bacteria are eliminated at a given time, biofilms allow for quick growth and recontamination of a surface or area if the associated biofilm is not treated. Rapid amplification Biofilm acts as an ideal breeding ground for the rapid amplification of bacteria and dangerous pathogens by providing ideal environments and nutrient deposits. Why testing matters Testing for biofilm in pipes and other water sources is one of the most important safety strategies that property owners can use. By performing regular evaluations, biofilm-forming bacteria colonies can be eradicated before they have an opportunity to turn into an outbreak of disease and infection. Because you can find potentially dangerous pathogens such as Legionella in biofilm, it is important to check for its presence regularly. Vigilance can help property owners and managers prevent biofilm formation and protect the health and safety of employees and the general public. Being prepared with a water management plan is crucial, especially if a test does discover biofilm in water lines. Information from:cdc.govhttps://www.corrosionpedia.com/definition/1649/biofilmhttp://www.rroij.com/
