{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T09:35:09Z","timestamp":1788168909067,"version":"build-2803163510"},"reference-count":43,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2025,4,25]],"date-time":"2025-04-25T00:00:00Z","timestamp":1745539200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Co-trimoxazole is an antibacterial drug, a mixture of sulfamethoxazole (SMX) and trimethoprim (TMP) in a ratio of 5:1. Due to the different susceptibility of both components to decomposition under the influence of sunlight, the aim of the study was to assess the change in bacteriostatic activity during irradiation of the mixture of these antibiotics in a sunlight simulator. The bacteriostatic activity was assessed using a Microbial Assay for Risk Assessment (MARA), monitoring drug concentrations as well as the formation of photodegradation products using liquid chromatography (LC). The toxicity analysis of the SMX and TMP mixture showed synergistic bacteriostatic activity for six bacterial strains. This activity was maintained even during sample irradiation when 80\u201390% of SMX was degraded. This may indicate the bacteriostatic effect of SMX photoproducts and\/or the lack of necessity to maintain a 5:1 ratio between SMX and TMP to maintain a strong effect of the mixture of these antibiotics. Analysis using LC with a high-resolution mass spectrometry detector revealed the presence of 11 SMX degradation products, including two with preserved sulfonamide structure, which may exhibit bacteriostatic activity.<\/jats:p>","DOI":"10.3390\/molecules30091907","type":"journal-article","created":{"date-parts":[[2025,4,25]],"date-time":"2025-04-25T06:10:13Z","timestamp":1745561413000},"page":"1907","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Individual and Simultaneous Photodegradation of Trimethoprim and Sulfamethoxazole Assessed with the Microbial Assay for Risk Assessment"],"prefix":"10.3390","volume":"30","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4945-3687","authenticated-orcid":false,"given":"Grzegorz","family":"Na\u0142\u0119cz-Jawecki","sequence":"first","affiliation":[{"name":"Department of Toxicology and Food Science, Medical University of Warsaw, 02-091 Warszawa, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Milena","family":"Wawryniuk","sequence":"additional","affiliation":[{"name":"Department of Toxicology and Food Science, Medical University of Warsaw, 02-091 Warszawa, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Weronika","family":"Kopczy\u0144ska","sequence":"additional","affiliation":[{"name":"Department of Toxicology and Food Science, Medical University of Warsaw, 02-091 Warszawa, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2567-4453","authenticated-orcid":false,"given":"Joanna","family":"Giebu\u0142towicz","sequence":"additional","affiliation":[{"name":"Department of Drug Chemistry, Pharmaceutical and Biomedical Analysis, Medical University of Warsaw, 02-091 Warszawa, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,4,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"417","DOI":"10.1016\/j.chemosphere.2008.11.086","article-title":"Antibiotics in the aquatic environment\u2014A review\u2014Part I","volume":"75","year":"2009","journal-title":"Chemosphere"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Hubeny, J., Harnisz, M., Korzeniewska, E., Buta, M., Zieli\u0144ski, W., Rolbiecki, D., Giebu\u0142towicz, J., Na\u0142\u0119cz-Jawecki, G., and P\u0142aza, G. (2021). Industrialization as a source of heavy metals and antibiotics which can enhance the antibiotic resistance in wastewater, sewage sludge and river water. PLoS ONE, 16.","DOI":"10.1371\/journal.pone.0252691"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"121665","DOI":"10.1016\/j.watres.2024.121665","article-title":"Antimicrobials and antimicrobial resistance genes in the shadow of COVID-19 pandemic: A wastewater-based epidemiology perspective","volume":"257","author":"Xu","year":"2024","journal-title":"Water Res."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"928","DOI":"10.1016\/j.chemosphere.2011.06.058","article-title":"Ecotoxicity evaluation of selected sulfonamides","volume":"85","author":"Stolte","year":"2011","journal-title":"Chemosphere"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Madej-Knysak, D., Adamek, E., and Baran, W. (2024). Biodegradation of photocatalytic degradation products of sulfonamides: Kinetics and identification of intermediates. Int. J. Mol. Sci., 25.","DOI":"10.3390\/ijms25126688"},{"key":"ref_6","unstructured":"ESVAC Report (2025, February 04). Sales of Veterinary Antimicrobial Agents in 31 European Countries in 2022. Trends from 2010 to 2022. 13th ESVAC Report. European Medicines Agency. Available online: https:\/\/www.ema.europa.eu\/en\/documents\/report\/sales-veterinary-antimicrobial-agents-31-european-countries-2022-trends-2010-2022-thirteenth-esvac-report_en.pdf."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1821","DOI":"10.1021\/tx500267x","article-title":"Antibacterial activity of sulfamethoxazole transformation products (TPs): General relevance for sulfonamide TPs modified at the para position","volume":"27","author":"Majewsky","year":"2014","journal-title":"Chem. Res. Toxicol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2735","DOI":"10.1016\/j.watres.2010.02.006","article-title":"Effect of water-matrix composition on Trimethoprim solar photodegradation kinetics and pathways","volume":"44","author":"Sirtori","year":"2010","journal-title":"Water Res."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1016\/j.envpol.2017.01.003","article-title":"Usage, residue, and human health risk of antibiotics in Chinese aquaculture: A review","volume":"223","author":"Liu","year":"2017","journal-title":"Environ. Pollut."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"5788","DOI":"10.1007\/s11356-017-0861-x","article-title":"Occurrence of antimicrobial agents, drug resistant bacteria and genes in the sewage-impacted Vistula (Poland)","volume":"25","author":"Tyski","year":"2018","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1016\/j.chemosphere.2014.04.075","article-title":"Distribution and ecological risk of antibiotics in a typical effluent-receiving river (Wangyang River) in north China","volume":"112","author":"Jiang","year":"2014","journal-title":"Chemosphere"},{"key":"ref_12","unstructured":"European Union (2020). Commission Implementing Decision (EU) 2020\/1161 Decision (EU) 2020\/1161 of 4 August 2020 Establishing a Watch List of Substances for Union-Wide Monitoring in the Field of Water Policy Pursuant to Directive 2008\/105\/EC of the European Parliament and of the Council. Off. J. Eur. Union, L257, 32\u201335."},{"key":"ref_13","unstructured":"European Union (2022). Commission Implementing Decision (EU) 2022\/1307 Decision (EU) 2022\/1307 of 22 July 2022 establishing a watch list of substances for Union-wide monitoring in the field of water policy pursuant to Directive 2008\/105\/EC of the European Parliament and of the Council. Off. J. Eur. Union, L197, 117\u2013121."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1016\/j.scitotenv.2015.08.014","article-title":"Phototransformation of sulfamethoxazole under simulated sunlight: Transformation products and their antibacterial activity toward Vibrio fischeri","volume":"538","author":"Gmurek","year":"2015","journal-title":"Sci. Tatal Environ."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1292","DOI":"10.1016\/j.chemosphere.2009.09.065","article-title":"Photodegradation of sulfamethoxazole in various aqueous media: Persistence, toxicity and photoproducts assessment","volume":"77","author":"Nogueira","year":"2009","journal-title":"Chemosphere"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1098","DOI":"10.1016\/S1001-0742(12)60167-3","article-title":"Effects of environmental factors on sulfamethoxazole photodegradation simulated sunlight irradiation: Kinetics and mechanism","volume":"25","author":"Niu","year":"2013","journal-title":"J. Environ. Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1327","DOI":"10.1016\/j.watres.2011.12.052","article-title":"Trimethoprim: Kinetic and mechanistic considerations in photochemical environmental fate and AOP treatment","volume":"46","author":"Luo","year":"2012","journal-title":"Water Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"109889","DOI":"10.1016\/j.envres.2020.109889","article-title":"Individual and simultaneous degradation of sulfamethoxazole and trimethoprim by ozone, ozone\/hydrogen peroxide and ozone\/persulfate processes: A comparative study","volume":"189","author":"Adil","year":"2020","journal-title":"Environ. Res."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3922","DOI":"10.1016\/j.watres.2009.04.006","article-title":"Degradation of sulfamethoxazole in water by solar photo-Fenton. Chemical and toxicological evaluation","volume":"43","author":"Nogueira","year":"2009","journal-title":"Water Res."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"95","DOI":"10.1016\/j.jphotochem.2018.04.014","article-title":"Individual and simultaneous degradation of the antibiotics sulfamethoxazole and trimethoprim in aqueous solutions by Fenton, Fenton-like and photo-Fenton processes using solar and UV radiations","volume":"360","author":"Mota","year":"2018","journal-title":"Photochem. Photobiol. Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2573","DOI":"10.1021\/acs.est.5b05604","article-title":"UV\/H2O2 and UV\/PDS treatment of trimethoprim and sulfamethoxazole in synthetic human urine: Transformation products and toxicity","volume":"50","author":"Zhang","year":"2016","journal-title":"Environ. Sci. Technol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"52233","DOI":"10.1007\/s11356-024-34659-y","article-title":"From bacteria to fish: Ecotoxicological insights into sulfamethoxazole and trimethoprim","volume":"31","author":"Diogo","year":"2024","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"10575","DOI":"10.1021\/es202237g","article-title":"Oxidation of trimethoprim by ferrate(VI): Kinetics, products, and antibacterial activity","volume":"45","author":"Anquandah","year":"2011","journal-title":"Environ. Sci. Technol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1016\/S0003-2670(03)00404-5","article-title":"Microplate-based microbial assay for risk assessment and (eco)toxic fingerprinting of chemicals","volume":"485","author":"Gabrielson","year":"2003","journal-title":"Anal. Chim. A"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"300","DOI":"10.1016\/j.trac.2007.01.011","article-title":"Low-cost ecotoxicity testing of environmental samples using microbiotests for potential implementation of the Water Framework Directive","volume":"26","author":"Wadhia","year":"2007","journal-title":"Trends Anal. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"487","DOI":"10.1002\/tox.20593","article-title":"Application of microbial assay for risk assessment biotest in evaluation of toxicity of human and veterinary antibiotics","volume":"25","author":"Wadhia","year":"2010","journal-title":"Environ. Toxicol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"579","DOI":"10.1016\/j.jhazmat.2014.08.050","article-title":"Electrochemical degradation of sulfonamides at BDD electrode: Kinetics, reaction pathway and eco-toxicity evaluation","volume":"280","author":"Stepnowski","year":"2014","journal-title":"J. Hazard. Mater."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Gan, X., Song, Y., Liu, G., Zhang, H., and Yang, J. (2023). The efficient degradation and mechanism of sulfamethoxazole using ZnO\/ZnIn2S4 heterojunction under visible light. Front. Environ. Sci., 11.","DOI":"10.3389\/fenvs.2023.1314536"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"119297","DOI":"10.1016\/j.apcatb.2020.119297","article-title":"Sulfamethoxazole degradation by visible light assisted peroxymonosulfate process based on nanohybrid manganese dioxide incorporating ferric oxide","volume":"278","author":"Guo","year":"2020","journal-title":"Applied Cat. B Environ."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1007\/s40201-021-00769-9","article-title":"Oxidative degradation of sulfamethoxazole from secondary treated effluent by ferrate(VI): Kinetics, by-products, degradation pathway and toxicity assessment","volume":"20","author":"Jebalbarezi","year":"2022","journal-title":"J. Environ. Health Sci. Eng."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Ljubas, D., Jureti\u0107, H., Badrov, A., Bio\u0161i\u0107, M., and Babi\u0107, S. (2023). Photocatalytic degradation of pharmaceutical trimethoprim in aqueous solution over nanostructured TiO2 film irradiated with simulated solar radiation. Appl. Sci., 13.","DOI":"10.3390\/app13095681"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1016\/j.scitotenv.2012.05.003","article-title":"Solar photocatalytic treatment of trimethoprim in four environmental matrices at a pilot scale: Transformation products and ecotoxicity evaluation","volume":"430","author":"Michael","year":"2012","journal-title":"Sci. Total Environ."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"149802","DOI":"10.1016\/j.cej.2024.149802","article-title":"Degradation of oxytetracycline by ferrate(VI): Treatment optimization, UHPLC-MS\/MS and toxicological studies of the degradation products, and impact of urea and creatinine on the removal","volume":"485","author":"Thomas","year":"2024","journal-title":"Chem. Eng. J."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.chemosphere.2010.04.011","article-title":"Comparing the sensitivity of algal, cyanobacterial and bacterial bioassays to different groups of antibiotics","volume":"80","author":"Pikkemaat","year":"2010","journal-title":"Chemosphere"},{"key":"ref_35","unstructured":"World Health Organization (2024, November 04). Model List of Essential Medicines. Available online: https:\/\/list.essentialmeds.org."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"3148","DOI":"10.1021\/acs.est.6b03038","article-title":"Photolysis of antibiotics under simulated sunlight irradiation: Identification of photoproducts by high-resolution mass spectrometry","volume":"51","year":"2017","journal-title":"Environ. Sci. Technol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"3933","DOI":"10.1021\/es0353053","article-title":"Photochemical fate of sulfa drugs in the aquatic environment: Sulfa drugs containing five-membered heterocyclic groups","volume":"38","author":"Boreen","year":"2004","journal-title":"Environ. Sci. Technol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"171027","DOI":"10.1016\/j.scitotenv.2024.171027","article-title":"How data on transformation products can support the redesign of sulfonamides towards better biodegradability in the environment","volume":"921","author":"Puhlmann","year":"2024","journal-title":"Sci. Total Environ."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"615","DOI":"10.1007\/s43630-022-00340-x","article-title":"A kinetic study of the photolysis of sulfamethoxazole with special emphasis on the photoisomer","volume":"22","author":"Palm","year":"2023","journal-title":"Photochem. Photobiol. Sci."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"2665","DOI":"10.1002\/jctb.7748","article-title":"Rapid activation of PMS driven by bimetallic redox on transition metal selenides for sulfamethoxazole degradation: Mechanism, degradation pathway and intermediates toxicity","volume":"99","author":"Wang","year":"2024","journal-title":"J. Chem. Technol. Biotechnol. B"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"158929","DOI":"10.1016\/j.cej.2024.158929","article-title":"Sustainable dual-cathode photoelectron-Fenton system enabling oxidative and reductive removal of pollutants via visible light driving Fe sites conversion","volume":"504","author":"Liu","year":"2025","journal-title":"Chem. Eng. J."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"162711","DOI":"10.1016\/j.apsusc.2025.162711","article-title":"Synergistic electric fields induced by unilateral doping modulations for enhanced organic pollutant degradation and sterilization","volume":"692","author":"Fu","year":"2025","journal-title":"Appl. Surf. Sci."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Na\u0142\u0119cz-Jawecki, G., Mielniczek, J., Wawryniuk, M., Giebu\u0142towicz, J., and Drobniewska, A. (2025). The Microbial Assay for Risk Assessment (MARA) in the Assessment of the Antimicrobial Activity of Ofloxacin and Its Photoproducts. Int. J. Mol. Sci., 26.","DOI":"10.3390\/ijms26062595"}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/30\/9\/1907\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:21:20Z","timestamp":1760030480000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/30\/9\/1907"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,4,25]]},"references-count":43,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2025,5]]}},"alternative-id":["molecules30091907"],"URL":"https:\/\/doi.org\/10.3390\/molecules30091907","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,4,25]]}}}