Impact/Purpose:

1. To assess the prevalence of nontuberculous Mycobacterium species (NTM) in raw water, finished water, and in drinking water distribution systems before and after the addition of filtration and ozonation.

2. To assess the effect of the addition of filtration and ozonation on the percent of NTM from environmental sources that are genetically related to human isolates derived from the population served by municipal drinking water.

3. To assess the effect of the addition of filtration and ozonation on the prevalence of indicator bacteria and heterotrophic plate count bacteria in finished water and in drinking water distribution system biofilm. A comparison of strains of heterotrophic bacteria before and after the treatment change will be conducted.

4. To assess the effect of the addition of filtration and ozonation on the prevalence of other pathogens in finished water, and in drinking water distribution systems.

Description:

Mycobacterium species are classified as rod-shaped acid-fast, bacteria in the family Mycobacteriaceae. They are ubiquitous throughout the environment, and are commonly found in environmental samples of soil, and ambient surface waters. NTM have been isolated from drinking water nationwide, in raw and distributed water. It is believed that NTM may survive in treated drinking water, protected from disinfection by their intracellular location in free-living amoebae and in this manner may enter distribution systems. Because of their size, amoebae are most likely to seed the distribution systems of unfiltered drinking water or systems in which there has been a drinking water failure. NTM are particularly persistent in low-flow areas such as dead-end pipes within the plumbing of buildings. Recovery of Mycobacteria is difficult, since most species are relatively slow-growing. Recovery from the environment typically has the highest yield during the summer months when ambient temperatures are higher.

Some species of NTM act as human pathogens; the young, the elderly and the immunocompromised are most likely to develop clinical illness. Drinking water as a source of NTM infections is well documented, although the relative contribution of drinking water as a source of human NTM infections is unknown.

Seattle Public Utilities (SPU) delivers drinking water via the regional water system to approximately 1.3 million persons in the City of Seattle and in King County, Washington. Customers receive water directly from SPU or indirectly from one of 27 wholesale water utilities that buy water from SPU. Two primary surface water sources are used: the Cedar River and the South Fork of the Tolt River. Currently these surface water sources are unfiltered.

Due to concerns about organic loading on the Tolt (and consequently higher disinfection byproduct formations), SPU is adding a direct filtration plant on the South Fork of the Tolt R. The new plant will come on line in late 2000. Ozone will be used for primary disinfection, and chlorine will be used for secondary disinfection.

This task description describes NERL's component of a collaborative project involving NHEERL, NERL, NRMRL, CDC and Region 10 to evaluate if the introduction of filtration and ozonation changes the microenvironmental conditions that favor the deposition and growth of Mycobacteria sp. in drinking water distribution systems. NERL - Cincinnati is responsible for the analysis of NTM samples and submission of NTM isolates to the Centers for Disease Control (CDC) for identification and genetic relatedness studies

Record Details:

Record Type:PROJECT

Start Date:06/01/2000

Projected Completion Date:09/01/2003

OMB Category:Other

Record ID: 58011

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Project Information:

Progress :NTM were isolated from water samples collected from several sites in both systems before the change in treatement technology at the Tolt plant. The treatment change occurred at the Tolt system December 2000-January 2001. High rate monomedia antracite filtration was added along with ozonation. Sixty (60) samples were analyzed for NTM prior to treatment change, of these 15 samples were NTM -positive . Nine of the NTM-positive isolates were identifed as M. avium. Thus far none of the environmental isolates showed genetic relatedness to patient isolates from the same geographical area. Ninety- six (96) samples have been analyzed for NTM after the treatment change. Twenty - one (21) of the samples were NTM - positive. The isolates were sent to CDC for identification and multi-locus enzyme electrophoresis. The last sampling for this project will occur in Nov. 02.

Relevance :This study may produce information useful to the water treatment industry and public health officials concerning the impact of treatment changes on the microbial population in drinking water distribution systems. Successful culmination of this task would lead to better understanding of the biologic and physiological factores that lead to persistence of M. avium and other NTM in drinking water distribution systems. A better understanding of the ecology of these organisms in drinking water distributions systems is a important step in reducing the exposure to these important opportunistic pathogens. M/DBP Research Plan Relationship: Topic area Ex.M.14. In addition research performed under this task is a high priority under the CCL; the results of this study could potentially allow OGWDW to make recommendations to drinking water systems on how to prevent these CCL List 1 organisms from getting into their potable water.

Clients :Dr. Paul Berger, OGWDW

Project IDs:

ID Code :373

Project type :OMIS