Metals, sulfate in water heighten risk for mycobacterial infections in cystic fibrosis

Key takeaways:

• Greater levels of sulfate and vanadium in water heightened the odds for a Mycobacterium avium complex infection.
• Patients had an increased likelihood for Mycobacterium abscessus with molybdenum in water.

Among patients with cystic fibrosis, increases in sulfate and specific metals in water raised the odds for nontuberculosis mycobacterial infections, according to results published in Environmental Epidemiology.

“Our findings that trace metals, specifically vanadium and molybdenum, increase the risk for nontuberculosis mycobacterial (NTM) disease service to reinforce our findings from prior studies conducted at a state level,” Ettie M. Lipner, PhD, staff scientist in the epidemiology and population studies unit of the National Institute of Allergy and Infectious Diseases laboratory of clinical immunology and microbiology, told Healio.

In a population-based case-control study, Lipner and colleagues evaluated 3,897 U.S. patients from the Cystic Fibrosis Foundation Patient Registry between 2010 and 2019 to determine what water-quality constituents put these patients at risk for NTM pulmonary infections, such as Mycobacterium avium complex (MAC) and Mycobacterium abscessus.

Researchers used the Water Quality Portal to obtain data on water quality they linked to patients based on their county of residence.

Across 11 U.S. states (Arizona, California, Colorado, Connecticut, Maine, Massachusetts, Nevada, New Mexico, Rhode Island, Utah and Wyoming), more patients had MAC (n = 484; mean age, 29.8 years; 51.3% women) than M. abscessus (n = 222; mean age, 26.7 years; 45.5% women).

The remaining 2,816 individuals (mean age, 25.5 years; 47.2% women) with cystic fibrosis did not test positive for any NTM infection.

Researchers found that the likelihood for MAC increased by 41% with each 1-standardized unit increase in the log concentration of zinc in water. Greater levels of sulfate in water also raised the odds for MAC by 39%, as did the metal vanadium by 21%, according to researchers.

Researchers did not find a link between M. abscessus and higher levels of zinc, sulfate or vanadium in water; however, rising levels of mercury in drinking water contributed to 45% greater odds for this infection. Additional constituents of water that heightened the odds for this infection included the metal molybdenum by 36% and phosphorus by 25%.

Following adjustment for significant demographic and clinical variables, only a few constituents continued to be linked to higher odds for each infection. Greater levels of sulfate and vanadium raised the chances for a MAC infection by 36% and 13%, respectively, whereas more molybdenum in water heightened the likelihood for M. abscessus by 28%.

Of the states including in this analysis, researchers observed that counties in central and southern California and Nevada, southern Arizona, central and northern New Mexico, Colorado and Wyoming had the highest predicted probability for contracting a MAC infection. Patients who resided in Colorado and New Mexico also had the greatest predicted probability for a M. abscessus infection.

Notably, researchers also found lower odds for infections with higher levels of some water constituents in the adjusted model. For example, each 1-standardized unit increase in the log concentration of chromium lowered the chances for MAC by 22% and M. abscessus by 19%. Higher levels of manganese in water also reduced the odds for MAC by 21%.

“Our studies are in the discovery phase, and we have not yet determined an intervention for these particular findings,” Lipner told Healio.

“Our future studies are focused on identifying the implications for individual patients and ascertaining the role of these trace metals in disease susceptibility and progression,” Lipner added. “We will be conducting clinical studies, as well as studies using animal models.”

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