Water Source May Be Associated With Risk of Nontuberculous Mycobacterial Infection

An anaysis of nontuberculous mycobacterial (NTM) diagnostic tests for 15 years, water disinfection treatment, and water sources has found that where a city gets it water can increase the risk of NTM infection more than how the water is treated.

Nontuberculous mycobacterial (NTM) infections are primarily acquired from environmental sources and are responsible for significant morbidity, mortality, and healthcare costs. The source of water may have a larger impact on NTM infections than how the water is treated, according to new findings.

A new study in mSphere, a journal from the American Society for Microbiology, analyzed NTM diagnostic tests for 15 years along with information on municipal water treatment practices and sources of water for 140 cities in Michigan.

“A possible relationship between monochloramine disinfection of drinking water and NTM infection risk had not been investigated previously, though higher NTM concentrations are frequently recovered from chloraminated drinking water than from chlorinated water,” the authors explained.

A total of 9895 patients and test records from Michigan Medicine were included in the study. Of those, only 468 (4.7%) had at least 1 NTM-positive result. The NTM-positive patients had a mean age of 54.5 years versus 50.5 for the NTM-negative patients. NTM-positive patients were also more likely to be female (51.3%) versus NTM-negative patients (48.2%).

Only the cities of Ann Arbor, East Lansing, and Lansing used monochloramine for secondary disinfection of drinking water while the rest of the cities used chlorine. In addition, drinking water for 98 cities (70%) came primarily from surface water while drinking water for the rest of the cities came from groundwater. The majority of patients lived in cities where the drinking water came from surface water (83.9%) and was treated with chlorine (77.6%).

Patients living in a city with surface water drinking water had a 1.46 times higher likelihood of having an NTM infection. The odds were slightly reduced to 1.24 using an inverse propensity score weighted regression analysis. However, the logistic regression model and inverse propensity score weighted regression both showed that monochloramine disinfection was not associated with NTM infection.

“This is important given that regulations that limit drinking water concentrations of disinfection by-products, which are formed primarily when chlorine disinfection is used, incentivize drinking water utilities to change from chlorine to monochloramine disinfection,” the authors concluded.


Kotlarz N, Raskin L, Zimbric M, Errickson J, LiPuma JJ, Caverly LJ. Retrospective analysis of nontuberculous mycobacterial infection and monochloramine disinfection of municipal drinking water in Michigan. mSphere. 2019;4(4). doi: 10.1128/mSphere.00160-19.

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