Zimapan dam in Mexico, a reservoir of extended-spectrum-beta-lactamase-producing bacteria and arsenic resistance Barrage de Zimapan au Mexique, réservoir de bactéries productrices de bêta-lactamases à spectre étendu et de résistance à l¿arsenic Academic Article in Scopus uri icon

abstract

  • Description of the subject. In aquatic environments, prolonged exposure to heavy metals and/or antimicrobials selects for resistant bacteria, increasing the health risk for the population. Objectives. To evaluate antimicrobial and arsenic (As) resistance, presence of addiction systems and biofilm production in Gram-negative bacilli isolated from the Zimapan dam. Method. Surface water was sampled from 10 sites in the western area of the dam. CHROMagar¿ ESBL and mSuperCARBA¿ plates were used to isolate fermenting (FGB) and non-fermenting (NFGB) Gram-negative bacilli resistant to beta-lactams and carbapenems, respectively. Resistance was verified by the agar-diffusion method and double-disk synergy test. Genes for extended spectrum beta-lactamases (ESBL), carbapenemases and addiction systems were detected by PCR. Biofilm production and resistance to As and/or cefotaxime (CTX) were measured by spectrophotometry. The tolerance As was determined by serial dilution in LB agar adding variable concentrations of Na3 AsO2. Results. Of 47 beta-lactams resistant strains, 77.5% produced ESBL, with blaCTX-M (38% and 62%) and blaTEM-2 (41% and 51%) genes being detected in pisciculture and recreational areas, respectively. Significant resistance to imipenem and meropenem was detected, although no carbapenemase genes were detected; relE, pnd, ccdA, and vagC addiction system genes were the most frequent. Nineteen strains showed resistance up to 183 ppm of Na3 AsO2, 11 strains at 400 ppm and 3 strains up to 2,000 ppm. Biofilm production was detected in 83% of the strains. Conclusions. Contamination of the Zimapan dam with multidrug-resistant, biofilm-forming, As-and CTX-tolerant bacteria with different plasmid addiction systems requires urgent prevention and environmental control strategies. © 2023, University of Liege Faculty of Gembloux Agro-Bio Tech. All rights reserved.

publication date

  • January 1, 2023