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

Abstract

Summary 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 resistant 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 identification 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 susceptibility 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. Conclusion: Domestic sewage is an important source of β-lactams resistant determinants in Brazil.