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Transformations of antibiotics in water systems and the impact on specific microbes
Author(s) -
Beavan Abigail,
Bhatnagar Ashita,
Henkes Zoe,
Peller Julie,
Dick Sara
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.777.13
Subject(s) - antibiotics , bacteria , antibiotic resistance , chemistry , microbiology and biotechnology , escherichia coli , staphylococcus aureus , pathogenic bacteria , sulfamethoxazole , water treatment , environmental chemistry , biology , biochemistry , environmental engineering , environmental science , genetics , gene
Penicillin (Pen G) and Bactrim (sulfamethoxazole and trimethoprim) are two of the most commonly prescribed antibiotics used to target gram positive and gram negative bacteria, respectively. Usage of these medications often results in un‐metabolized antibiotics being discharged into water systems. Bacteria in those water systems can gain resistance from being exposed to low concentrations of these antibiotics. To better understand the lifetimes of antibiotics in water systems and the corresponding impacts on microbes, the decomposition and oxidation of Pen G and Bactrim in water solutions were studied. The bacteria selected for the study were Staphylococcus aureus (gram positive) and Escherichia coli (gram negative) due to their abundance and pathogenic capabilities. Antibiotic resistance in these species of bacteria is especially of concern to human health, since these bacteria have the ability to transfer resistance genes to other cells. The decomposition of 50 uM antibiotic solutions were studied in pure water and in solutions representing natural water: 10 ppm Dissolved Organic Material (DOM), 5mM NaHCO 3 , and both DOM and NaHCO 3. The concentration of the antibiotics was monitored weekly. In separate experiments under the same conditions, the antibiotics were oxidized via hydroxyl radicals using gamma radiolysis. To determine compound concentrations, solutions were analyzed using Ultra High Performance‐Liquid Chromatography‐Mass Spectrometry (UHPLC). Simultaneously to the UHPLC analysis, the solutions were plated on lawns of each bacteria. Following overnight incubation, bacteria susceptibility ring measurements were performed to determine the effects of these solutions on the behavior of S. aureus and E. coli . The UHPLC data showed that Pen G in pure water decomposed completely within two weeks. The rate of decomposition of Pen G in the DOM solutions was substantially slower, as Pen G remained in solution after thirteen weeks, where the concentration was measured as 15uM. The bacteria plates displayed susceptibility ring sizes that corresponded to the decreasing concentration of the Pen G, whether by natural decomposition or hydroxyl radical‐mediated oxidation. In both cases, the fully decomposed/oxidized Pen G was ineffective as an antibiotic. Pen G resistant colonies of the bacteria were found on almost all the plates tested. The Bactrim solutions are currently being analyzed and the results will be presented.