Impact/Purpose:

Determine the potential for colonization and growth of nontuberculous mycobacteria in point-of-use water treatment devices under actual use conditions sufficient for OW to determine whether or not guidance is needed. Those NTM that are of particular interest are those belonging to th M. avium complex ( M. avium, M. intracellulare and M x).

Description:

Treated potable water contains a variety of nontuberculous mycobacteria (NTM) that are indigenous to aquatic environments and are not entirely eliminated by treatment. These opportunistic pathogens are potentially harmful to individuals whose body defenses are impaired. Reverse osmosis(RO) filters and granular activated carbon (GAC) filters, which are often used to remove chemicals from potable water, adsorb nutrient materials and may provide a means through which NTMs can multiply to infectious levels. We have preliminary evidence from our earlier studies that NTMs, including M. avium complex (MAC) species, replicate on different types of filters. These include a RO filter in a building in Los Angeles, a GAC filter in a hospital in Cincinnati and in pour-through filters left at room temperatures. The objective of this study is to determine the potential for colonization and growth of nontuberculous mycobacteria, particularly those of the M. avium complex, in point-of-use water treatment devices under actual use conditions. Water from homes or buildings known to contain NTMs, particularly those of the M. avium complex, will be passed through various types of filters at regular intervals. This will provide the opportunity of NTM colonization in the presence of other indigenous flora that may either enhance or inhibit the specific pathogen. Samples of filter eluates will be analyzed to monitor the density of these organisms throughout the life of the filter, from installation to the recommended replacement date. The final results will allow a determination of whether NTM can colonize a variety of POU filter types when the filters are used in a real-world situation. This information could lead to guidance being issued to US consumers on the use and maintenance of these filters.

Record Details:

Record Type:PROJECT

Start Date:11/01/2000

Projected Completion Date:12/01/2005

OMB Category:Other

Record ID: 18293

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Project Information:

Progress :A request for proposals was posted in July, 2000; six proposals were received and evaluated by one in-house and two extramural reviewers. An award was made to the Olive View/UCLA Education and Research Instute, effective on July 1, 2001. Several types of RO and GAC filters were installed at the Olive View hospital complex. Water eluted from these filters was periodically tested for the presence of notuberculous mycobacteria (NTM). Mycobacteria including, M. intracellulare, were eluted from all types of filters; however, most of the mycobacteria were rapid growers rather than MAC. There was no evidence of actual colonization of RO filters by M. intracellulare. There was some colonization of GAC filters by M. intracellulare, but in most cases the rapid growing mycobacteria appeared to inhibit the slow growing M. intracellulare. One notable exception was that one of the "bacteriostatic" filters supported the growth of significant numbers of M. intracellulare. This was probably due to the fact that the inhibitors were silver and zinc, two substances to which MAC organisms are resistant. The absence of other bacteria that could potentially crowd out the MAC may actually make these "bacteriostatic" filters more hospitable to MAC. Because the rapidly growing NTM amplified to greater numbers than the MAC and some of the rapid growers are opportunistic pathogens, an additional effort was funded to identify the species of slow growing NTM that grew to the highest densities on the filters. The project period was also extended for an additional year.

Relevance :

Point-of-use (POU) filters may be the cause of significant exposures to NTM. If so, indivduals who are most vulnerable to infection need to be advised as to which types of filters they should avoid using. The work also relates to Topic area Ex.M.19 in EPA's Microbial/Disinfection By-Product Research Plan. In addition research performed under this task is a high priority under the CCL; M. avium is a CCL List 1 pathogen. The information obtained in this study will be used by OGWDW in deciding whether or not it should issue guidance regarding the use of these filters. This guidance could take the form of advising these POU filter users that would be at high risk of NTM infection (e.g. those immunocompromised) to avoid certain filter types and/or a warning to strictly heed the manufacturers recommendations regarding filter replacement times.

Clients :Dr. Paul Berger, OGWDW

Research Component :M/DBP (MICROBIAL)

Risk Paradigm :EXPOSURE

Progress :A request for proposals was posted in July, 2000; six proposals were received and evaluated by one in-house and two extramural reviewers. An award was made to the Olive View/UCLA Education and Research Instute, effective on July 1, 2001. Several types of RO and GAC filters were installed at the Olive View hospital complex. Water eluted from these filters was periodically tested for the presence of notuberculous mycobacteria (NTM). Mycobacteria including, M. intracellulare, were eluted from all types of filters; however, most of the mycobacteria were rapid growers rather than MAC. There was no evidence of actual colonization of RO filters by M. intracellulare. There was some colonization of GAC filters by M. intracellulare, but in most cases the rapid growing mycobacteria appeared to inhibit the slow growing M. intracellulare. One notable exception was that one of the "bacteriostatic" filters supported the growth of significant numbers of M. intracellulare. This was probably due to the fact that the inhibitors were silver and zinc, two substances to which MAC organisms are resistant. The absence of other bacteria that could potentially crowd out the MAC may actually make these "bacteriostatic" filters more hospitable to MAC. Because the rapidly growing NTM amplified to greater numbers than the MAC and some of the rapid growers are opportunistic pathogens, an additional effort was funded to identify the species of slow growing NTM that grew to the highest densities on the filters. The project period was also extended for an additional year.

Relevance :

Point-of-use (POU) filters may be the cause of significant exposures to NTM. If so, indivduals who are most vulnerable to infection need to be advised as to which types of filters they should avoid using. The work also relates to Topic area Ex.M.19 in EPA's Microbial/Disinfection By-Product Research Plan. In addition research performed under this task is a high priority under the CCL; M. avium is a CCL List 1 pathogen. The information obtained in this study will be used by OGWDW in deciding whether or not it should issue guidance regarding the use of these filters. This guidance could take the form of advising these POU filter users that would be at high risk of NTM infection (e.g. those immunocompromised) to avoid certain filter types and/or a warning to strictly heed the manufacturers recommendations regarding filter replacement times.

Clients :Dr. Paul Berger, OGWDW

Research Component :CCL (MICROBIAL)

Risk Paradigm :EXPOSURE

Project IDs:

ID Code :EX.M.19

Project type :ORD-DW Plan

ID Code :4033

Project type :OMIS