Untitled

Failure to eradicate non-tuberculous mycobacteria upon disinfection of heater–cooler units: results of a microbiological investigation in northwestern Italy

“…Being a well established environmental source of NTM, drinking water has been extensively studied to characterize the risk of human exposure to such bacteria [21][22][23]. In particular, the water contained in HCUs has been shown to harbor various pathogens, including NTM, commonly found in hospital drinking water, some of which can pose serious health risks for immunocompromised individuals [24][25][26].…”

Molecular Survey of the Occurrence of Legionella spp., Mycobacterium spp., Pseudomonas aeruginosa, and Amoeba Hosts in Two Chloraminated Drinking Water Distribution Systems

“…Similarly, a high diversity of mycobacteria, some of which, such as M. avium, M. intracellulare, M. kansasii, M. abscessus, and M. chelonae (33,47,65,73,77), are known to be opportunistic pathogens, has been demonstrated to be characteristic of the drinking water environment; among those species, M. avium is currently on the U.S. EPA candidate contaminant list. In the present study, a considerable number of mycobacteria were detected, accounting for 0.1% to 68% of total bacterial estimate, assuming that each bacterium has a single copy of the 16S rRNA gene.…”

Distribution System Water Quality Affects Responses of Opportunistic Pathogen Gene Markers in Household Water Heaters

“…Although influence of pipe materials on bacterial numbers and microbial communities in bulk water and biofilm have been extensively studied in real and simulated distribution systems, 20,46−49 few studies have investigated the effect of upstream pipe material on downstream microbial regrowth, especially with respect to opportunistic pathogens. 50,51 One recent study indicated that upstream copper pipes decreased overall microbial diversity in downstream biofilm, but promoted L. pneumophila colonization. 51 Another study found that replacing old pipes (likely metal-based pipes) with corrosion-resistant plastic pipes in a municipal distribution network reduced downstream colonization of mycobacteria, 50 supporting the notion that upstream pipe materials and their status (e.g., aging, corrosion) can be a major factor governing downstream opportunistic pathogen regrowth.…”

“…50,51 One recent study indicated that upstream copper pipes decreased overall microbial diversity in downstream biofilm, but promoted L. pneumophila colonization. 51 Another study found that replacing old pipes (likely metal-based pipes) with corrosion-resistant plastic pipes in a municipal distribution network reduced downstream colonization of mycobacteria, 50 supporting the notion that upstream pipe materials and their status (e.g., aging, corrosion) can be a major factor governing downstream opportunistic pathogen regrowth. In the present study, much higher (∼2 log) P. aeruginosa in SWHs receiving water from chloraminated cement SDSs relative to iron and PVC SDSs (during Stage 1) is likely due to favorable chemistry and microbial composition of cement SDS water toward P. aeruginosa persistence in SWHs.…”