Annual changes in the occurrence of antibiotic-resistant coliform bacteria and enterococci in municipal wastewater.

Wastewater contains subinhibitory concentrations of different micropollutants such as antibiotics that create selective pressure on bacteria. This phenomenon is also caused by insufficient wastewater treatment technology leading to the development and spread of antibiotic-resistant bacteria and resistance genes into the environment. Therefore, this work focused on monitoring of antibiotic-resistant coliform bacteria and enterococci in influent and effluent wastewaters taken from the second biggest wastewater treatment plant (Petrzalka) in the capital of Slovakia during 1 year. Antibiotic-resistant strains were isolated, identified, and characterized in terms of susceptibility and biofilm production. All of 27 antibiotic-resistant isolates were identified mainly as Morganella morganii, Citrobacter spp., and E. coli. Multidrug-resistance was detected in 58% of isolated strains. All tested isolates could form biofilm; two strains were very strong producers, and 74% formed biofilm by strong intensity. The flow rate of the influent wastewater had a more significant impact on the number of studied bacteria than the temperature. Graphical abstract.

Prevalence of antibiotic-resistant coliform bacteria, Enterococcus spp. and Staphylococcus spp. in wastewater sewerage biofilm.

OBJECTIVES: Urban wastewater contains various micropollutants and a high number of different micro-organisms. Some bacteria in wastewater can attach to surfaces and form biofilm, which gives bacteria an advantage in the fight against environmental stresses. This work focused on analysis of bacterial communities in biofilms isolated from influent and effluent sewerage of a wastewater treatment plant (WWTP) in Bratislava, Slovakia. METHODS: Detection of biofilm microbiota was performed by culture-independent and -dependent approaches. The composition of bacterial strains was detected by denaturing gradient gel electrophoresis fingerprinting coupled with construction of 16S rRNA clone libraries. Analysis of the concentration of antibiotics and the prevalence of antibiotic-resistant coliforms, Enterococcus spp. and Staphylococcus spp. in sewerage was also studied. RESULTS: Biofilm collected at the inlet point was characterised primarily by the presence of Pseudomonas spp., Acinetobacter spp. and Janthinobacterium spp. clones, whilst members of the genus Pseudomonas were largely detected in biofilm isolated in outflow of the WWTP. Predominant antibiotics such as azithromycin, clarithromycin and ciprofloxacin were found in influent wastewater. The removal efficiency of these antibiotics, notably azithromycin and clarithromycin, was 30% in most cases. CONCLUSION: The highest number of antibiotic-resistant bacteria, with a predominance of coliforms, was detected in samples of effluent biofilm. Multidrug-resistant strains in effluent biofilm showed very good biofilm-forming ability.

Dominant psychoactive drugs in the Central European region: A wastewater study.

The aim of this study was to analyze 26 various illicit drugs, psychopharmaceuticals and metabolites thereof in sewer from 17 selected wastewater treatment plants (WWTPs) in the Slovak and Czech Republics. Urinary bio-markers used were analyzed using liquid chromatography coupled with the tandem mass spectrometry (LC-MS/MS). We then compared our results with data obtained in other parts of Europe and the world. The present study shows that the Slovak and Czech Republics have one of the highest methamphetamine consumption rates in Europe. Within Slovakia, the highest level of methamphetamine consumption was found in Dunajská Streda with the mean specific load of the drug in sewage being up to 479mg/day/1000 inhabitants; the next highest load was detected in Trnava (354mg/day/1000 inhabitants). The methamphetamine, ecstasy and cannabis consumptions in our study were comparable to those found in other European cities, whereas cocaine consumption was lower. Among all of the studied psychopharmaceuticals, tramadol and venlafaxine were represented in the highest concentrations. The highest mean specific load of tramadol was detected in the spa town of Piestany (371mg/day/1000 inhabitants) and Kosice (372mg/day/1000 inhabitants), while the highest mean loads of venlafaxine were recorded for the towns of Trencín (230mg/day/1000 inhabitants) and Piestany (108mg/day/1000 inhabitants).