Resistência antimicrobiana de Escherichia coli Escherich (1885) isolada do Rio Alegria no município de Medianeira - PR

Abstract

Water resources are recipient bodies of raw and treated effluents, which daily receive drugs and microorganisms that interact in the aquatic environment, such as Escherichia coli (E. coli), which is of fecal origin and often pathogenic. Through constant exposure to antimicrobials, many bacteria become resistant to antibiotics in these environments, which in turn act as a means of dispersing resistant microbial populations and favor the insertion of genes into natural bacteria. Thus, the present study aimed to evaluate the antimicrobial resistance of Escherichia coli strains isolated from three collection points in Rio Alegria, PR. For microbiological analysis of the water, the Most Probable Number (MPN) technique was used, with quantification of thermotolerant coliforms, and subsequent confirmation of E. coli in Methylene Blue Eosin Agar (EMB) medium. E. coli strains were isolated on nutrient agar to obtain inoculum in saline water equivalent to a 0.5 tube on the McFarland scale. The antibiogram was performed following the methodology described in the Brazilian Committee on Antimicrobial Susceptibility Testing (BrCAST), with seven antimicrobials: ciprofloxacin (5 mcg), norfloxacin (10 mcg), ampicillin (10 mcg), nitrofurantoin (300 mcg), gentamicin (10 mcg), amikacin (30 mcg) and ceftriaxone (30 mcg), using the disk-diffusion assay in Mueller Hinton Agar culture medium. Inhibition halos were measured and classified as sensitive, intermediate or resistant according to the tables provided by BrCAST. And finally, the calculation of the multiple antimicrobial resistance index (MAR) was performed. It was possible to verify the presence of thermotolerant coliforms in all collection points, with greater numbers of thermotolerant ones in points 1 and 2, located in the rural area and downtown, respectively. After performing the susceptibility test, the collection point that most presented antimicrobial resistant isolates was point 2 located in the urban area, followed by point 1 and finally point 3, demonstrating greater resistance to the antibiotics ampicillin, norfloxacin and ciprofloxacin. And finally, after calculating the MAR index, points 1 and 2 showed multidrug resistance isolates, and of all the isolates studied in the three points, 17.4% showed values above 0.2. At the analyzed collection points, the Alegria River demonstrates to act as a selective environment for the maintenance and propagation of resistance genes due to the receipt of sanitary sewage, industrial effluents and agricultural activity.