MICROBIAL CONTAMINATION OF THREE RIVERS CROSSING SOFIA CITY

Abstract

Water is an important factor for all living creatures. In some organisms, it makes up 90% of body weight. In humans, its percentage varies between 55-65%. Water covers about 71% of the planet's surface. That is why it is necessary to protect it from various types of pollution with physical, chemical and biological substances. Rivers are the main sources because they provide water for drinking-domestic water supply, industry, animal husbandry, agriculture, etc. Attention should be paid to the quality of surface waters, an adequate assessment of microbiological contamination and their sanitary condition should be made. However, antimicrobial resistance is constantly increasing. The number of deaths is expected to rise from 700,000 in 2014 to 10 million by 2025. This is the first report of the microbial contamination of three rivers crossing Sofia city – Darvenishka River, Vladayska River (before the Wastewater Treatment Plant (WWTP) near Kubratovo) and Iskar River (after WWTP Kubratovo). According the REGULATION №12 from 18.06.2002 and the number of colony forming units in 100 ml the waters of the Darvenishka River belong to Category 2 according to the contents of fecal streptococci and Category 3 – according to the contents of E. coli and coliforms. The waters of the Vladayska River fall into Category 2. The waters of the Iskar River at the sampling point are classified as Category 3 according to the total coliform and Category 2 according to the fecal streptococci content. We isolated 12 single bacterial cultures from water and sludge of Darvenishka River and characterized theme biochemically by BD Phoenix M50. According the EUCAST cut-off values we determined their susceptibility against 8 groups of antibiotics and most of them were multiresistant.