Occurrence changes of Escherichia coli (including O157:H7 serotype) in wastewater and sewage sludge by quantitation method of (EMA) real time-PCR

There are hundreds of Escherichia coli serotypes and among them enterohaemorrhagic strain E. coli O157:H7 causing gastrointestinal disorders such as: bloody diarrhea, cramping and abdominal pain and the infectious "hemolytic uremic syndrome". Therefore, it's important to develop some rapid and reliable methods of detecting this pathogen in wastewater and sewage sludge. This will allow one to determine the potential risk of infection for humans and animals as far as wastewater and sewage management is concerned. E. coli non- and -O157:H7 gene copies were detected in primary influents and final effluents in winter from municipal wastewater treatment plant. The ethidium monoazide bromide (EMA) application revealed false-positive detection of this bacteria in final effluents. In spring and summer, E. coli gene was not found either in wastewater or in sludge. In autumn, E. coli genes were found in primary influents (20,000 copies of gene/100 mL) and final effluents (2,511 copies of gene/100 mL). High amounts of E. coli O157: H7 gene were detected in both kinds of sludge: waste activated sludge (3,890,451 copies of gene/100 mL) and final sewage sludge (1,819,700 copies of gene/100 mL). We detected the large amount of "free DNA" that is derived from dead cells, which can give false-positive results (overestimation). The use of EMA will make it possible to avoid this inconvenience and allow for effective and appropriate selection of EMA concentration, however, it needs further analysis.