Researchers from the University of Colorado, Boulder have now shown that the regions in the United States where pathogenic mycobacteria are most prevalent in showerheads are the same regions where nontuberculous mycobacterial (NTM) lung infections are most common.

The study, published in the journal, mBio, emphasizes the important role of showerheads in the transmission of NTM infections.

Bacteria thrive in showerheads and throughout household water distribution systems. While most of these bacteria are innocuous, some are potential pathogens, including members of the genus Mycobacterium that can cause NTM lung infection, a threat to public health. The researchers surveyed showerheads in households across the United States and Europe and found that showerheads "often harbor abundant mycobacterial communities that vary in composition depending on geographic location, water chemistry, and water source," according to the study.

Households that received water treated with chlorine disinfectants had particularly high abundances of certain mycobacteria.

Their results highlight the public health relevance of mycobacteria in showerhead biofilms and advance our understanding of NTM transmission dynamics. This study demonstrates that mycobacterial distributions in showerheads are often predictable from household location and water chemistry. The results will help develop strategies to reduce exposures to these emerging pathogens.