Antimicrobial resistance and ESBL genes in E. coli isolated in proximity to a sewage treatment plant.

This study was aimed to determine the prevalence of antibiotic-resistant Escherichia coli in the Szreniawa river with detailed aims of: (i) assessment of differences in the number of microbiological indicators of water quality in a diurnal cycle in a vicinity of the sewage treatment plant (STP); (ii) determination of prevalence of antimicrobial resistant E. coli isolated from three sites located at varying locations toward the STP; (iii) evaluation of the presence of extended-spectrum beta lactamase (ESBL)-determining genes in waterborne E. coli isolated from three sites of Szreniawa and (iv) genetic similarity assessment among the E. coli populations. Bacteriological contamination (coliforms, E. coli, E. faecalis) was assessed using membrane filtration. Fifty E. coli strains, the species of which was confirmed by MALDI-TOF analysis, were subjected to antimicrobial resistance tests using standard disk-diffusion method. Double disk synergy test was used to assess the ESBL production and PCR tests were conducted to detect the ESBL-conferring genes and evaluate the genetic diversity. A significant variation in the number of bacteriological indicators was observed both within and between the sampling sites, suggesting the effect of effluent from the STP, point discharge of household sewage and agricultural runoff on the water contamination. The resistance to amoxicillin/clavulanate (90%) and ampicillin (36%) was most prevalent. Multidrug resistance was observed in 40% of strains but no ESBL-producing strains were observed phenotypically. However, the presence of three ESBL-determining genes (TEM, OXA and CTX-M) was detected in 24, 10 and 8% of strains, respectively. A number of factors caused considerable pollution of the river and numerous multidrug resistant E. coli strains were isolated.

The effect of anthropogenic pressure shown by microbiological and chemical water quality indicators on the main rivers of Podhale, southern Poland.

This study was aimed to determine the spatial variation in anthropogenic pressure exerted on surface water in the Podhale region (southern Poland), which is one of the most popular tourist destinations in Poland. The assessment was based on the dynamics and relationships between microbiological and chemical indicators of water quality throughout the major rivers of this region-Dunajec, Czarny Dunajec, Bialy Dunajec, and Bialka. Another aim was to assess the effect of land use on the quality of water in the studied rivers. The study was conducted over 1 year at 21 sampling sites distributed from the uppermost sections of rivers in the Tatra National Park through main tourist resorts until mouths of the considered rivers to the Czorsztynskie Lake. Microbiological analysis comprised the prevalence of total and fecal types of coliforms and Escherichia coli, mesophilic, and psychrophilic bacteria. Chemical assays determined the concentrations of Na+, K+, NH4+, Cl-, NO3-, and PO43-. Temperature, electrical conductivity, and pH were measured onsite. It was demonstrated that there is a significant relationship between the predominant types of land use within individual catchments, which results in evident differences in the pollution of waters between the catchments. The results showed that increased share of built-up areas and arable land results in significant deterioration of water quality. Thus, waters of Czarny Dunajec were the cleanest, while Bialy Dunajec was the most heavily contaminated. Also, spatial diversity in water quality was shown-the cleanest waters were sampled in the Tatra National Park and the pollution increased with the course of rivers. Point sources of pollution such as effluents from treatment plants or discharge of untreated sewage from households proved to be more important than non-point sources, such as surface runoff. Moreover, the important role of the Czorsztynskie Lake in the purification of water was demonstrated.