Fate of Escherichia coli experimentally injected in a drinking water distribution pilot system

Fass, S.; Dincher, Marie; Reasoner, Donald J.; Gatel, D.; Block, J. C.

doi:10.1016/0043-1354(96)00100-5

Cited by 60 publications

(37 citation statements)

References 15 publications

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“…Similar results showing the presence and possible growth of coliforms within distribution systems were obtained previously by using culturing techniques (20,21). Long-term survival of E. coli cultures exposed to low-nutrient conditions has been documented previously (7,12,23). However, this is the first time that the presence of metabolically active E. coli indigenous to distribution system water has been shown within a biofilm by using direct microscopic techniques.…”

Section: Vol 69 2003 Growth Of E Coli In Biofilms 5467mentioning

confidence: 93%

“…Several lines of evidence suggest the longterm survival of total coliforms and/or E. coli in distribution system biofilms. Among these are the recovery of total coliforms from distribution systems in which water leaving the treatment plant tested negative for coliforms (20,21); the observation that environmentally derived strains of total coliforms and E. coli can grow in unsupplemented distribution system water (7); and the recovery of increased numbers of E. coli organisms from drinking water distribution pilot plants after the calculated inoculum should have theoretically washed out (12). Other studies have shown that E. coli can attach and become incorporated into biofilms within model distribution systems (8,11), as well as into biofilms derived from groundwater populations (2).…”

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confidence: 99%

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Growth of Escherichia coli in Model Distribution System Biofilms Exposed to Hypochlorous Acid or Monochloramine

Williams

Braun-Howland

2003

Appl Environ Microbiol

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Bacteria indigenous to water distribution systems were used to grow multispecies biofilms within continuous-flow slide chambers. Six flow chambers were also inoculated with an Escherichia coli isolate obtained from potable water. The effect of disinfectants on bacterial populations was determined after exposure of established biofilms to 1 ppm of hypochlorous acid (ClOH) for 67 min or 4 ppm of monochloramine (NH 2 Cl) for 155 min. To test the ability of bacterial populations to initiate biofilm formation in the presence of disinfectants, we assessed the biofilms after 2 weeks of exposure to residual concentrations of 0.2 ppm of ClOH or 4 ppm of NH 2 Cl. Lastly, to determine the effect of recommended residual concentrations on newly established biofilms, we treated systems with 0.2 ppm of ClOH after 5 days of growth in the absence of disinfectant. Whole-cell in situ hybridizations using fluorescently tagged, 16S rRNA-targeted oligonucleotide probes performed on cryosectioned biofilms permitted the direct observation of metabolically active bacterial populations, including certain phylogenetic groups and species. The results of these studies confirmed the resistance of established bacterial biofilms to treatment with recommended levels of disinfectants. Specifically, Legionella pneumophila, E. coli, and ␤ and ␦ proteobacteria were identified within biofilms both before and after treatment. Furthermore, although it was undetected using routine monitoring techniques, the observation of rRNA-containing E. coli within biofilms demonstrated not only survival but also metabolic activity of this organism within the model distribution systems. The persistence of diverse bacterial species within disinfectant-treated biofilms suggests that current testing practices underestimate the risk to immunocompromised individuals of contracting waterborne disease.Assessment of the microbiological safety of drinking water is based largely on the routine monitoring of water supplies for the presence of total coliforms and Escherichia coli. Detection of E. coli is considered indicative of recent fecal contamination and of the potential presence of enteric pathogens, while the presence of total coliforms is indicative of poor water quality.Whereas routine water quality measurements assess the presence of planktonic bacteria, the vast majority of bacteria indigenous to aquatic environments exist attached to solid particles or surfaces. Within water distribution systems, significant bacterial populations exist as complex, structurally heterogeneous biofilms attached to pipe surfaces. Residence within these complex matrices provides organisms with higher localized nutrient concentrations than are commonly found in drinking waters (10,14,18,22), and recent studies have shown that attached bacteria are more metabolically active than are their free-living counterparts (26, 29). Furthermore, biofilms afford bacteria significant protection from disinfecting agents (3, 31, 35), including hypochlorous acid and monochloramine. Biofilms are dynamic ...

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Section: Vol 69 2003 Growth Of E Coli In Biofilms 5467mentioning

confidence: 93%

mentioning

confidence: 99%

Growth of Escherichia coli in Model Distribution System Biofilms Exposed to Hypochlorous Acid or Monochloramine

Williams

Braun-Howland

2003

Appl Environ Microbiol

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“…Of concern is the survival of pathogenic E. coli for extended periods of time under the comparatively nutrient-deprived conditions of untreated well water, bottled water, municipal drinking water, natural water bodies, and water distribution systems (24,52,53,54). As such, further investigation into the role of rpoS in the survival of E. coli O157:H7 biofilm cells in both natural and treated water samples is required.…”

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confidence: 99%

Role of rpoS in Escherichia coli O157:H7 Strain H32 Biofilm Development and Survival

Sheldon

Yim

Saliba

et al. 2012

Appl Environ Microbiol

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bThe protein RpoS is responsible for mediating cell survival during the stationary phase by conferring cell resistance to various stressors and has been linked to biofilm formation. In this study, the role of the rpoS gene in Escherichia coli O157:H7 biofilm formation and survival in water was investigated. Confocal scanning laser microscopy of biofilms established on coverslips revealed a nutrient-dependent role of rpoS in biofilm formation, where the biofilm biomass volume of the rpoS mutant was 2.4-to 7.5-fold the size of its rpoS ؉ wild-type counterpart in minimal growth medium. The enhanced biofilm formation of the rpoS mutant did not, however, translate to increased survival in sterile double-distilled water (ddH 2 O), filter-sterilized lake water, or unfiltered lake water. The rpoS mutant had an overall reduction of 3.10 and 5.30 log 10 in sterile ddH 2 O and filter-sterilized lake water, respectively, while only minor reductions of 0.53 and 0.61 log 10 in viable counts were observed for the wild-type form in the two media over a 13-day period, respectively. However, the survival rates of the detached biofilm-derived rpoS ؉ and rpoS mutant cells were comparable. Under the competitive stress conditions of unfiltered lake water, the advantage conferred by the presence of rpoS was lost, and both the wild-type and knockout forms displayed similar declines in viable counts. These results suggest that rpoS does have an influence on both biofilm formation and survival of E. coli O157:H7 and that the advantage conferred by rpoS is contingent on the environmental conditions.

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“…There has been much work reported on the fate of waterborne organisms artificially introduced into experimental systems, with often conflicting results (Camper et al 1991(Camper et al , 1998Fass et al 1996;Block et al 1997;Wiedenmann et al 1997;Sibelle et al 1998). Some workers have postulated that E. coli could grow in the distribution system within Numbers in boxes are average numbers of E. coli 1-1 using one years data.…”

Section: Fate Of E Coli In Distribution Systemsmentioning

confidence: 99%

The fate ofEscherichia colithrough water treatment and in distribution

McMath

Holt

2000

Journal of Applied Microbiology

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SUMMARY The removal of E. coli bacteria at each stage of water treatment is presented, showing how the filtration stages contribute most to reduction of bacterial numbers in the water. At treatment works without filtration stages, the emphasis is put on catchment management to limit contamination of the raw water and ensure that the numbers of viable E. coli in the source water remain low. Routine monitoring of the raw water provides data on seasonal trends in numbers of E. coli bacteria and allows effective management of supply. In the UK there is no evidence that E. coli grows in the water distribution system, whether in the planktonic stage or within biofilms (O'Neill et al. 1997). The detection of E. coli in the distribution system is rare and prompts a thorough investigation. Repeat samples are taken from the point which originally failed, along with a number of hydraulically linked samples including samples from hydrants. The response to the detection of E. coli is discussed. A series of experiments carried out on a pilot pipe system is briefly described and the results discussed in relation to the routine samples taken in the Thames Water Supply area.

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Fate of Escherichia coli experimentally injected in a drinking water distribution pilot system

Cited by 60 publications

References 15 publications

Growth of Escherichia coli in Model Distribution System Biofilms Exposed to Hypochlorous Acid or Monochloramine

Growth of Escherichia coli in Model Distribution System Biofilms Exposed to Hypochlorous Acid or Monochloramine

Role of rpoS in Escherichia coli O157:H7 Strain H32 Biofilm Development and Survival

The fate ofEscherichia colithrough water treatment and in distribution

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