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

Studies have shown that certain opportunistic pathogenic species of nontuberculous mycobacteria (NTM) can be present in distributed drinking water. However, detailed information about NTM population composition in drinking water is lacking. Therefore, NTM communities in unchlorinated drinking water from the distribution system of five treatment plants in the Netherlands were characterized using 454 pyrosequencing of the hsp65 gene. Results showed high diversities in unchlorinated drinking water, with up to 28 different NTM operational taxonomic units (OTUs) in a single sample. Each drinking water sample had a unique NTM community, and most (81.1%) OTUs were observed only once. One OTU was observed in 14 of 16 drinking water samples, indicating that this NTM species is well adapted to unchlorinated drinking water conditions. A clear influence of season, source type (groundwater, surface water), easily assimilable organic carbon (AOC) concentration, biofilm formation rate, and active biomass in treated water on the establishment of an NTM community in drinking water was not observed. Apparently, local conditions are more important for the development of a specific NTM community in the drinking water distribution system. A low (4.2%) number of hsp65 gene sequences showed more than 97% similarity to sequences of the opportunistic pathogens M. avium, M. genavense, and M. gordonae. However, most (95.8%) NTM hsp65 gene sequences were related to notyet-described NTM species that have not been linked to disease, indicating that most NTM species in unchlorinated drinking water from distribution systems in the Netherlands have a low public health significance. Several species of the genus Mycobacterium are described as nontuberculous mycobacteria (NTM), and these NTM species can be opportunistic pathogens, causing disease in immunocompromised humans (1). The drinking water environment provides niches for certain NTM species, since some species are capable of multiplying in biofilms, protozoa that graze on biofilms, and sediments (2-7). As a result, studies using cultivation methods have identified different NTM species isolated from drinking water (8-11). Moreover, several studies have suggested that NTM isolates from drinking water and from patients have the same genotype (12-17). Thus, drinking water can be a route of transmission of opportunistic pathogenic NTM species to immunocompromised humans.A large proportion of the NTM species in drinking water cannot be cultivated with the currently used culture methods (18). Consequently, cultivation-based studies provide a limited view of NTM communities in drinking water. A more complete characterization of the NTM populations in drinking water can be achieved by employing molecular methods such as PCR and sequencing, but such studies are still scarce (19,20). As a result, the NTM diversity in drinking water is still largely unexplored. A possible reason for this is that the generally used 16S rRNA gene sequence analysis is not suitable to investigate NTM populations, because...

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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

Wielen

Heijnen

Kooij

2013

“…galvanized (zinc coated) or made of copper, and the disinfectants and low organic carbon content of the water, which selectively favor the growth of some mycobacterial populations (78,79). Because of the identification of several pathogenicity factors and antibiotic resistance genes (Fig.…”

Section: Discussionmentioning

confidence: 99%

Biofilms on Hospital Shower Hoses: Characterization and Implications for Nosocomial Infections

Soto-Girón

Rodriguez-R

Luo

et al. 2016

e Although the source of drinking water (DW) used in hospitals is commonly disinfected, biofilms forming on water pipelines are a refuge for bacteria, including possible pathogens that survive different disinfection strategies. These biofilm communities are only beginning to be explored by culture-independent techniques that circumvent the limitations of conventional monitoring efforts. Hence, theories regarding the frequency of opportunistic pathogens in DW biofilms and how biofilm members withstand high doses of disinfectants and/or chlorine residuals in the water supply remain speculative. The aim of this study was to characterize the composition of microbial communities growing on five hospital shower hoses using both 16S rRNA gene sequencing of bacterial isolates and whole-genome shotgun metagenome sequencing. The resulting data revealed a Mycobacterium-like population, closely related to Mycobacterium rhodesiae and Mycobacterium tusciae, to be the predominant taxon in all five samples, and its nearly complete draft genome sequence was recovered. In contrast, the fraction recovered by culture was mostly affiliated with Proteobacteria, including members of the genera Sphingomonas, Blastomonas, and Porphyrobacter. The biofilm community harbored genes related to disinfectant tolerance (2.34% of the total annotated proteins) and a lower abundance of virulence determinants related to colonization and evasion of the host immune system. Additionally, genes potentially conferring resistance to ␤-lactam, aminoglycoside, amphenicol, and quinolone antibiotics were detected. Collectively, our results underscore the need to understand the microbiome of DW biofilms using metagenomic approaches. This information might lead to more robust management practices that minimize the risks associated with exposure to opportunistic pathogens in hospitals.

“…In a recent study, the occurrence of Mycobacterium spp., M. avium, L. pneumophila, P. aeruginosa, and Acanthamoeba spp. in chloraminated drinking water sampled from eight locations in the distribution systems of two treatment plants in the United States was determined by qPCR methods as well (58). The percentages of samples positive for Mycobacterium spp., L. pneumophila, and P. aeruginosa were similar to those observed in our study.…”

Section: Discussionmentioning

confidence: 99%

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

Wielen

Kooij

2013

112

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.