Mycobacteria in Water and Loose Deposits of Drinking Water Distribution Systems in Finland

Abstract

Drinking water distribution systems were analyzed for viable counts of mycobacteria by sampling water from waterworks and in different parts of the systems. In addition, loose deposits collected during mechanical cleaning of the main pipelines were similarly analyzed. The study covered 16 systems at eight localities in Finland. In an experimental study, mycobacterial colonization of biofilms on polyvinyl chloride tubes in a system was studied. The isolation frequency of mycobacteria increased from 35% at the waterworks to 80% in the system, and the number of mycobacteria in the positive samples increased from 15 to 140 CFU/liter, respectively. Mycobacteria were isolated from all 11 deposits with an accumulation time of tens of years and from all 4 deposits which had accumulated during a 1-year follow-up time. The numbers of mycobacteria were high in both old and young deposits (medians, 1.8 ؋ 10 5 and 3.9 ؋ 10 5 CFU/g [dry weight], respectively). Both water and deposit samples yielded the highest numbers of mycobacteria in the systems using surface water and applying ozonation as an intermediate treatment or posttreatment. The number and growth of mycobacteria in system waters correlated strongly with the concentration of assimilable organic carbon in the water leaving the waterworks. The densities of mycobacteria in the developing biofilms were highest at the distal sites of the systems. Over 90% of the mycobacteria isolated from water and deposits belonged to Mycobacterium lentiflavum, M. tusciae, M. gordonae, and a previously unclassified group of mycobacteria. Our results indicate that drinking water systems may be a source for recently discovered new mycobacterial species.

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

“…NTM were observed in drinking water by others using cultivation methods, but the numbers of positive samples ranged from 15% to 83% (8,(38)(39)(40)(41)(42)(43), lower than the 100% positive drinking water samples observed with qPCR in our study. A recent study demonstrated that cultivation methods give an underestimation of NTM in drinking water compared to estimation with qPCR (40).…”

“…Moreover, these results demonstrate that species belonging to the genus Mycobacterium can grow in drinking water (biofilms) at different but low levels of (easily biodegradable) organic carbon in the water. In contrast, by using cultivation methods, it was observed in Finland and the United States that mycobacterial numbers are positively correlated with AOC concentrations (39,43). This apparent discrepancy might be explained by differences in AOC levels, which were considerably higher and had larger ranges in the U.S. and Finnish studies (17 to 234 g C liter Ϫ1 and 38 to 350 g C liter Ϫ1 , respectively) than in our study (3.1 to 28.2 g C liter Ϫ1 ).…”

Molecular Isolation of Pathogenic Non-tuberculous Mycobacteria in Free Ranging Migratory Wildebeests (<i>Connochaetes taurinus</i>) and Cattle of Masai Mara, Kenya

“…Our findings are the first evidence of M. lentiflavum infection reported in Kenya. The main reservoir in the environment has not been firmly established, but organisms with M. lentiflavum-like 16S rRNA gene sequences were detected in soil samples from the UK and from France (Mendum et al, 2000) and the species seem to be frequently present in drinking water distribution systems in Finland (Torvinen et al, 2004).…”

Microbiological problems and biofilms associated with Mycobacterium chimaera in heater–cooler units used for cardiopulmonary bypass

“…Hydrophobicity varies between MAC species 64 . Both M. avium and M. intracellulare are recovered more frequently from pipe surfaces in biofilms, than in the planktonic phase 65,66 . However, M. intracellulare forms biofilms more readily than the less hydrophobic M. avium, which is more commonly found in the bulk water 65,67 Despite the global distribution and use of 3T HCUs, whole genome analysis has demonstrated a lack of genetic diversity between isolates 2, 4 .…”