Antibiotic-Resistant Microorganisms and Multiple Drug Resistance Determinants in Pseudomonas Bacteria from the Pushchino Wastewater Treatment Facilities

— The work presents characterization of antibiotic-resistant strains isolated by direct plating of five samples collected at different treatment stages from the Pushchino water treatment facilities in April 2015. Primary analysis of resistance of the collection (~800 strains) to the following antibiotics was carried out: carbenicillin, kanamycin, streptomycin, amikacin, tobramycin, chloramphenicol, rifampicin, gentamicin, tetracycline, ceftazidime, cefepime, and meropenem. Antibiotic-resistant bacteria most common in the Pushchino wastewater treatment facilities were found to belong to the genera Pseudomonas and Alcaligenes . Occurrence of tetracycline resistance genes was investigated, and predominance of the tetA / tetC genes responsible for active transport of this antibiotic from the cell were found to be predominant among the studied strains. The strains containing the genes associated with type I integrons ( intI1, qacE/qacE Δ 1, and sul1 ) constituted 25% of the studied ones. Four Pseudomonas strains were found to contain the IncN plasmids, while seven strains of this genus contained plasmids of the P-9 incompatibility group (ε-subgroup). Three IncP-9 plasmids were conjugative and carried simultaneously the determinants of tetracycline, streptomycin, and gentamicin resistance, which has not been previously reported for the ε-subgroup of IncP-9 plasmids.