Urban wastewater treatment plants as hotspots for antibiotic resistant bacteria and genes spread into the environment: a review.

Human pharmaceuticals in the aquatic environment: a challenge to Green Chemistry.

Antibiotics, disinfectants and bacteria resistant to them have been detected in environmental compartments such as waste water, surface water, ground water, sediments and soils. Antibiotics are released into the environment after their use in medicine, veterinary medicine and their employment as growth promoters in animal husbandry, fish farming and other fields. There is increasing concern about the growing resistance of pathogenic bacteria in the environment, and their ecotoxic effects. Increasingly, antibiotic resistance is seen as an ecological problem. This includes both the ecology of resistance genes and that of the resistant bacteria themselves. Little is known about the effects of subinhibitory concentrations of antibiotics and disinfectants on environmental bacteria, especially with respect to resistance. According to the present state of our knowledge, the impact on the frequency of resistance transfer by antibacterials present in the environment is questionable. The input of resistant bacteria into the environment seems to be an important source of resistance in the environment. The possible impact of resistant bacteria on the environment is not yet known. Further research into these issues is warranted.

Resistance in the Environment

The occurrence of pharmaceuticals and their metabolites and transformation products in the environment is becoming a matter of concern, because these compounds, which may have adverse effects on living organisms, are extensively and increasingly used in human and veterinary medicine and are released continuously into the environment. A variety of pharmaceuticals have been detected in many environmental samples worldwide. Their occurrence has been reported in sewage-treatment-plant effluents, surface water, seawater, groundwater, soil, sediment and fish. This paper provides an overview of recent scientific research on the sources, occurrence, and fate of pharmaceuticals in water and wastewater.

Occurrence patterns of pharmaceuticals in water and wastewater environments

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Resistance in the environment

Antibiotic resistance of E. coli in sewage and sludge.

ESBL-producing E. coli in Austrian sewage sludge.

Fungi, above all filamentous fungi, can occur almost everywhere, even in water. They can grow in such a quantity in water that they can affect the health of the population or have negative effects on food production. There are several reports of fungal growth in water from different countries, but to our knowledge none from Austria so far. The aim of this study was to gain an overview of the spectrum of filamentous fungi and yeasts in drinking water systems. Thirty-eight water samples from drinking water and groundwater were analysed. Fungi were isolated by using membrane filtration and plating method with subsequent cultivation on agar plates. The different taxa of fungi were identified using routine techniques as well as molecular methods. Fungi were isolated in all water samples examined. The mean value for drinking water was 9.1 CFU per 100 ml and for groundwater 5400 CFU per 100 ml. Altogether 32 different taxa of fungi were found. The taxa which occurred most frequently were Cladosporium spp., Basidiomycetes and Penicillium spp. (74.6%, 56.4% and 48.7%, respectively). This study shows that drinking water can be a reservoir for fungi, among them opportunists, which can cause infections in immunosuppressed patients.

Occurrence and hygienic relevance of fungi in drinking water

For some time now, antibiotic-resistant bacterial strains have been found in the human population, in foods, in livestock and wild animals, as well as in surface waters. The entry of antibiotics and resistant bacterial strains into the environment plays an important role in the spread of antibiotic resistance. The goal of the present study was to monitor the entry of antibiotic resistances into the environment through the contamination of wastewater. To assess the extent of transmission of antibiotic resistances from human sources into the environment, the resistance patterns of Escherichia coli strains isolated from human patients have been compared to those found in strains isolated from sewage sludge. Our results may indicate if resistances to particular antibiotics are more prone than others to spread into the environment. To monitor the increase of specific resistances over time, samples taken in the years 2000 and 2009 were analysed. Our study shows that for some antibiotics a parallel development of resistance patterns has taken place in both patient and environmental samples over time. For other sets of antibiotics, independent developments have occurred in the samples. A clear increase of multi-resistant E. coli strains over time was observed in samples from both sources.

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Franz Mascher

Papers

Antibiotic resistance of E. coli in sewage and sludge.

ESBL-producing E. coli in Austrian sewage sludge.

Occurrence and hygienic relevance of fungi in drinking water

Resistance patterns of Escherichia coli isolated from sewage sludge in comparison with those isolated from human patients in 2000 and 2009.

Comparison of extended-spectrum-β-lactamase (ESBL) carrying Escherichia coli from sewage sludge and human urinary tract infection.