Nontuberculous Mycobacteria from Plumbing | CDC EID

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Volume 17, Number 3–March 2011
Research
Nontuberculous Mycobacteria from Household Plumbing of Patients with Nontuberculous Mycobacteria Disease
Joseph O. Falkinham, III
Author affiliation: Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA

Suggested citation for this article

Abstract
To determine whether plumbing could be a source of nontuberculous mycobacteria (NTM) infection, during 2007–2009 I isolated NTM from samples from household water systems of NTM patients. Samples from 22/37 (59%) households and 109/394 (28%) total samples yielded NTM. Seventeen (46%) of the 37 households yielded >1 Mycobacterium spp. isolate of the same species as that found in the patient; in 7 of those households, the patient isolate and 1 plumbing isolate exhibited the same repetitive sequence-based PCR DNA fingerprint. Households with water heater temperatures <125°C (<50°C) were significantly more likely to harbor NTM compared with households with hot water temperatures >130°F (>55°C) (p = 0.0107). Although households with water from public or private water systems serving multiple households were more likely to have NTM (19/27, 70%) compared with households with a well providing water to only 1 household (5/12, 42%), that difference was not significant (p = 0.1532).

Nontuberculous mycobacteria (NTM) are opportunistic pathogens found in the environment (e.g., water and soil) and cause life-threatening infections in humans, other mammals, and birds (1,2). The incidence of NTM disease in Canada and the United States seems to be increasing (3–5). In Toronto, Ontario, Canada, NTM disease incidence rose from 1.5 to 9.0 cases per 100,000 population during 1997–2003 (3). The most common NTM infecting persons in the United States are Mycobacterium avium, M. intracellulare, and M. avium complex (MAC) (6). Infections occur in immunodeficient (e.g., HIV/AIDS) and immunosuppressed (e.g., cancer and transplant) patients and nonimmunosuppressed persons with the classic risk factors for mycobacteria infection, which include exposure to dust or smoke and underlying lung disease (6,7). Cystic fibrosis (8), heterozygosity for mutations in the cystic fibrosis transmembrane conductance regulator gene (9), and α-1-antitrypsin deficiency (10) predispose persons to NTM disease. Elderly, slender women lacking any of the classic risk factors for NTM disease are also at risk for NTM pulmonary disease (11–13). The major manifestation of NTM infection in the immunocompetent host is pulmonary disease, whereas disseminated disease (i.e., bacteremia) is found in patients with AIDS and other immunosuppressed persons (6).

NTM, particularly M. avium and M. intracellulare, have been recovered from a variety of environmental niches with which humans come in contact, especially drinking water (14–19). NTM are not transient contaminants of drinking water distribution systems; rather, the NTM grow and persist in plumbing (19,20). For example, numbers of mycobacteria increase in pipes as the distance from the treatment plant increases (19). NTM cell surface hydrophobicity results in disinfectant resistance and a predilection to attach to surfaces where NTM grow and form biofilms (21,22) that further increase disinfectant resistance (23). Because disinfectants inhibit the competing microflora, the slow-growing NTM can grow on the available nutrients in the absence of competition. M. avium can grow in drinking water at concentrations of assimilable organic carbon of >50 μg/L (24). Thus, there is strong reason to hypothesize that NTM can colonize and persist in household plumbing.

Sources of human infection with NTM, including MAC, have been found in water (18) and potting soil (25). Notably, M. avium was detected in water aboard the Russian space station Mir (26). Recently, researchers found that the DNA fingerprints of several M. avium isolates recovered from the shower of an M. avium–infected patient were almost identical to isolates recovered from the patient, indicating that the household water could have been the source of the patient's pulmonary disease (27). Despite that evidence, several publications have documented low frequency of recovery of MAC from household water samples (17,28–30). Such low recovery rates of M. avium and M. intracellulare could be because water samples, not biofilm, were collected. As MAC preferentially attaches to surfaces (21–23), MAC may be at low numbers in water samples. Furthermore, in the studies cited above, a low number (<4) of samples were collected from individual households. Recovery of multiple NTM or MAC isolates is necessary because of the clonal variation of MAC (25,27). The pilot study described here isolated, enumerated, and DNA fingerprinted NTM from households of patients with NTM to test the hypothesis that household plumbing could be a source of their NTM infection. full-text (large size): Nontuberculous Mycobacteria from Plumbing | CDC EID

Suggested Citation for this Article
Falkinham JO III. Nontuberculous mycobacteria from household plumbing of patients with nontuberculous mycobacteria disease. Emerg Infect Dis [serial on the Internet]. 2011 Mar [date cited]. http://www.cdc.gov/EID/content/17/3/419.htm


DOI: 10.3201/eid1703.101510


Comments to the Authors
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Joseph O. Falkinham, III, Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0406, USA; email: jofiii@vt.edu