Quantification of thermotolerant campylobacter in Swiss water treatment plants, by real-time quantitative polymerase chain reaction

A total of 49 wastewater samples from 23 different wastewater treatment plants (WWTPs) were analyzed using real-time quantitative polymerase chain reaction for the presence and quantity of thermotolerant campylobacters. Thermotolerant campylobacters were detected in 87.5% (21/24) and 64% (16/25) of untreated and treated wastewater samples, respectively. Their concentration was sufficiently high to be quantified in 20.4% (10/49) of the samples. In these samples, the concentration ranged from 68 000 to 2292 000 cells/L in untreated wastewater and from 10 800 to 28 000 cells/L in treated water. We conclude that thermotolerant campylobacters present a health hazard for workers at WWTPs in Switzerland. [Authors]

Biodiversity of amoebae and amoeba-associated bacteria in water treatment plants.

In this study, we enlarged our previous investigation focusing on the biodiversity of chlamydiae and amoebae in a drinking water treatment plant, by the inclusion of two additional plants and by searching also for the presence of legionellae and mycobacteria. Autochthonous amoebae were recovered onto non-nutritive agar, identified by 18S rRNA gene sequencing, and screened for the presence of bacterial endosymbionts. Bacteria were also searched for by Acanthamoeba co-culture. From a total of 125 samples, we recovered 38 amoebae, among which six harboured endosymbionts (three chlamydiae and three legionellae). In addition, we recovered by amoebal co-culture 11 chlamydiae, 36 legionellae (no L. pneumophila), and 24 mycobacteria (all rapid-growers). Two plants presented a similar percentage of samples positive for chlamydiae (11%), mycobacteria (20%) and amoebae (27%), whereas in the third plant the number of recovered bacteria was almost twice higher. Each plant exhibited a relatively high specific microbiota. Amoebae were mainly represented by various Naegleria species, Acanthamoeba species and Hartmannella vermiformis. Parachlamydiaceae were the most abundant chlamydiae (8 strains in total), and in this study we recovered a new genus-level strain, along with new chlamydiae previously reported. Similarly, about 66% of the recovered legionellae and 47% of the isolated mycobacteria could represent new species. Our work highlighted a high species diversity among legionellae and mycobacteria, dominated by putative new species, and it confirmed the presence of chlamydiae in these artificial water systems.

Estimating traveltimes and groundwater flow patterns using 3D time-lapse crosshole ERT imaging of electrical resistivity fluctuations induced by infiltrating river water

The infiltration of river water into aquifers is of high relevance to drinking-water production and is a key driver of biogeochemical processes in the hyporheic and riparian zone, but the distribution and quantification of the infiltrating water are difficult to determine using conventional hydrological methods (e.g., borehole logging and tracer tests). By time-lapse inverting crosshole ERT (electrical resistivity tomography) monitoring data, we imaged groundwater flow patterns driven by river water infiltrating a perialpine gravel aquifer in northeastern Switzerland. This was possible because the electrical resistivity of the infiltrating water changed during rainfall-runoff events. Our time-lapse resistivity models indicated rather complex flow patterns as a result of spatially heterogeneous bank filtration and aquifer heterogeneity. The upper part of the aquifer was most affected by the river infiltrate, and the highest groundwater velocities and possible preferential flow occurred at shallow to intermediate depths. Time series of the reconstructed resistivity models matched groundwater electrical resistivity data recorded on borehole loggers in the upper and middle parts of the aquifer, whereas the resistivity models displayed smaller variations and delayed responses with respect to the logging data. in the lower part. This study demonstrated that crosshole ERT monitoring of natural electrical resistivity variations of river infiltrate could be used to image and quantify 3D bank filtration and aquifer dynamics at a high spatial resolution.

Transepidermal water loss and resting energy expenditure in preterm infants.

Skin water loss of preterm infants, nursed naked in incubators under thermoneutral conditions, was assessed by a method based on the measurement of water vapor pressure gradient close to the skin surface. The corresponding skin evaporative heat loss was calculated using an energy equivalent of 0.58 kcal/g water vaporised. During the first 5 weeks of life, 128 sets of measurements were made on 56 infants whose gestational age ranged from 28 to 37 weeks. In the first week of life, infants of less than 30 weeks of gestation had substantially higher transepidermal water loss (TEWL) and skin evaporative heat loss (skin EHL) (41.5 +/- 11.5 g/kg X day TEWL; 24.1 +/- 6.5 kcal/kg X day skin EHL) than infants of 34 weeks and greater (11.1 +/- 4.1 g/kg X day; 6.4 +/- 2.4 kcal/kg X day). Infants of 30-33 weeks of gestation had intermediate values (22.4 +/- 7.6 g/kg X day; 13 +/- 4.4 kcal/kg X day). From the third week of life on, TEWL was similar for all preterm infants, i.e. 14.2 +/- 2.6 to 12.7 +/- 1.9 g/kg X day and corresponds to skin EHL of 8.2 +/- 1.5 to 7.4 +/- 1.1 kcal/kg X day. There was a significant inverse relationship between gestational age and TEWL and also between postnatal age and TEWL. In an additional group of 7 preterm infants (30-34 weeks of gestation, mean postnatal age of 21 +/- 9 days) transepidermal water loss and energy expenditure were measured simultaneously. The skin evaporative heat loss (8.8 +/- 2.5 kcal/kg X day) accounted for 17 +/- 5% of energy expenditure (53.3 +/- 4.1 kcal/kg X day). This study emphasizes that in infants of less than 30 weeks of gestation, the transepidermal water loss is of great importance and makes a major contribution to water and heat balances.

Transpiration stimulée afin d'améliorer l'équilibre hydro-sodé chez les patients hémodialysés : à propos d'un cas [Stimulated sweating in order to improve the water-and-salt balance in hemodialysis patients. A case report].

Obtaining the desired dry weight in dialysis patients is challenging once residual diuresis has disappeared, considering the trend of increasing dietary salt intake and shortening dialysis time over the last 40 years. We describe the case of a 55-year-old patient of Sudanese origin, who presented excessive interdialytic weight gain and hypertension on maintenance hemodialysis. After failure of conservative measures, a therapy of daily hot water baths of 30minutes each on non-dialysis days was introduced. All clinical parameters improved, including potassium profile. In this article, we review the history, pathophysiological mechanisms, efficacy and possible side effects of this interesting, somewhat forgotten technique.