Selection of antibiotic resistance by metals in a riverine bacterial community. (January 2021)

• Record Type: Journal Article
• Authors: Silva, Isabel; Tacão, Marta; Henriques, Isabel
• Is Part Of: Chemosphere. Volume 263(2021)
• Publication Date: 2021-01
• Subjects: Copper -- Zinc -- Antibiotic-resistant bacteria -- Antibiotic resistance genes -- Co-selection -- Microcosm; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.127936
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Antibiotic resistance is a health challenge across human, animal and environmental settings. In the environment, metals may contribute to antibiotic resistance selection. This study aimed to investigate the role of copper and zinc in the selection of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in a riverine bacterial community. Using a microcosm approach, bacteria in water samples were exposed to 50 μg L −1 and 100 μg L −1 of copper and zinc, for 20 days. The prevalence of ARB was determined from colony forming units counts in media with and without antibiotics. A significant increase in the prevalence of cefotaxime-resistant (from 2.3% in control to 9.5% in Cu50 and 16.8% in Cu100) and tetracycline-resistant bacteria (from 0.03% to 0.23% in Cu100) was observed in communities exposed to copper. Zinc exposure resulted in an increase in the prevalence of cefotaxime-resistant bacteria (from 24.6% to 91.3% in Zn50 and 72.4% in Zn100) and of kanamycin-resistant bacteria (from 6.1% to 24.1% in Zn50 and 43% in Zn100). Cefotaxime- and kanamycin-resistant bacteria belonged to genera intrinsically resistant to these compounds. DGGE profiling confirmed that metal exposure altered the structure and diversity of bacterial communities. Changes in the abundance of genes usually associated with mobile genetic elements ( bla CTX-M, bla TEM, tet (A) and intI1 ) were not detected after exposure. Results demonstrated the selection of bacteria intrinsically resistant to antibiotics imposed by copper and zinc exposure, suggesting an important role played by cross-resistance mechanisms. Highlights: Microcosms were used to study metal effects on antibiotic resistance selection. Cu exposure increased cefotaxime- and tetracycline-resistant bacteria prevalence. Zn exposure increased cefotaxime- and kanamycin-resistant bacteria prevalence. Metal exposure selected for bacteria intrinsically resistant to antibiotics. Abundance of acquired genes ( tet(A) and intI1 ) was not affected by metal exposure.