Nontuberculous Mycobacteria, Fungi, and Opportunistic Pathogens in Unchlorinated Drinking Water in the Netherlands

Abstract

aThe multiplication of opportunistic pathogens in drinking water supplies might pose a threat to public health. In this study, distributed unchlorinated drinking water from eight treatment plants in the Netherlands was sampled and analyzed for fungi, nontuberculous mycobacteria (NTM), and several opportunistic pathogens by using selective quantitative PCR methods. Fungi and NTM were detected in all drinking water samples, whereas Legionella pneumophila, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Aspergillus fumigatus were sporadically observed. Mycobacterium avium complex and Acanthamoeba spp. were not detected. Season had no influence on the occurrence of these organisms, except for NTM and S. maltophilia, which were present in higher numbers in the summer. Opportunistic pathogens were more often observed in premise plumbing water samples than in samples from the distribution system. The lowest number of these organisms was observed in the finished water at the plant. Thus, fungi, NTM, and some of the studied opportunistic pathogens can multiply in the distribution and premise plumbing systems. Assimilable organic carbon (AOC) and/or total organic carbon (TOC) had no clear effects on fungal and NTM numbers or on P. aeruginosa-and S. maltophilia-positive samples. However, L. pneumophila was detected more often in water with AOC concentrations above 10 g C liter ؊1 than in water with AOC levels below 5 g C liter ؊1 . Finally, samples that contained L. pneumophila, P. aeruginosa, or S. maltophilia were more frequently positive for a second opportunistic pathogen, which shows that certain drinking water types and/or sampling locations promote the growth of multiple opportunistic pathogens.

Pyrosequence Analysis of the hsp65 Genes of Nontuberculous Mycobacterium Communities in Unchlorinated Drinking Water in the Netherlands

“…These results show that a low BFR, AOC, and ATP concentration in drinking water has limited impact on the NTM community composition in the drinking water distribution system. A previous study had shown van der Wielen et al that the AOC and/or BFR of the drinking water did not affect the 16S rRNA gene copy numbers of NTM in unchlorinated drinking water in the Netherlands (38). It can be concluded from our studies that both the NTM numbers and NTM community composition cannot be controlled by further reduction of the microbial activity, AOC concentration, and/or BFR in unchlorinated drinking water in the Netherlands.…”

“…Consequently, the different NTM populations in winter and summer samples in the distributed drinking water of plant SW1 might indicate that NTM communities differ between the premise plumbing and distribution systems. A seasonal effect on the NTM numbers in distributed drinking water has been observed before (38,39), as has an effect of the premise plumbing system (25,38). Therefore, additional experiments are required to determine whether the NTM community in distributed drinking water is affected by the season and/or the premise plumbing system.…”

“…It is, therefore, better to use other developed qPCR assays for the quantitative detection of NTM in the drinking water environment (18,37). One of these qPCR assays has also been used for the quantitative detection of NTM in unchlorinated drinking water in the Netherlands (38).…”

Dynamics of microbial communities in an integrated ultrafiltration–reverse osmosis desalination pilot plant located at the Arabian Gulf

“…Given that the dosage of P. aeruginosa required to infect 50% of the tested mice hosts ranged from 5 x 10 3 till 2 x 10 4 cells [41], the amount of P. aeruginosa in the UF permeate was lower than the required infectious dosage and should not impose any significant risk to the public health. Coincidentally, the regA gene of P. aeruginosa was also occasionally detected in drinking water in Netherlands at up to 4.4 x 10 3 copies/L [42], suggesting that P. aeruginosa may be ubiquitous in oligotrophic drinking water supplies including those potable waters generated from a desalination plant. Finally, despite an increased abundance of genus Pseudomonas after CEB cleaning, the black coloration of bacterial cultures was not observed for these chemically cleaned UF membranes ( Figure 7B).…”

Host Response to Nontuberculous Mycobacterial Infections of Current Clinical Importance

“…In untreated water, NTM can even parasitize amoebae (4,5). Even when the water supply is treated, NTM persist, and a very recent study in Holland (6) found NTM in samples of drinking water from eight separate treatment plants.…”