Occurrence of extended-spectrum betalactamase (ESBL) and carbapenemases among ampicillin-resistant enterobacteriales recovered from a municipal raw sewage in Minas Gerais, Brazil

Abstract

Introduction: The capacity of resistance to β-lactam among enterobacteriales is notable, mainly into water environment. Herein, many species of this family have the ability to carrier and produce β-lactamases enzymes, such as extended-spectrum β-lactamases (ESBLs) and carbapenemases. However, contrary to clinical settings, where the distribution of resistant bacteria is well documented, the evidence of resis-tant pathogens in the domestic sewage has been little explored, especially in Brazil. Thus, we aimed to investigate the occurrence of ESBL and carbapenemases between ampicillin-resistant enterobacteriales recovered from a municipal raw sewage in Minas Gerais, Brazil. Methods: Enterobacteriales were isolated from sewage samples on MacConkey agar supplemented with ampicillin. Species identifica-tion was performed by biochemical and morphological methods and the resistance profile determined by the Kirby-Bauer test. The production of ESBL and carbapen-emase was investigated in all isolates by phenotypic tests. Results and discussion:A total of 45 species of enterobacteriales resistant to ampicillin were recovered (37 Escherichia coli, four Klebsiella pneumoniae, and one Klebsiella oxytoca, Citrobacter freundii and Pantoea agglomerans). Most isolates showed a high β-lactam suscep-tibility profile (14/45, 31.1 %), however E. coli with decreased susceptibility to imipenem was detected (2/37; 2.7 %). ESBL-positive isolates were mostly identified as E. coli (10/45; 22.2 %), but no isolates were positive carbapenemase. Conclu-sion: Domestic sewage is an important source of β-lactams resistant determinants in Brazil.