{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T18:01:44Z","timestamp":1784916104377,"version":"3.55.0"},"reference-count":50,"publisher":"Public Library of Science (PLoS)","issue":"7","license":[{"start":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T00:00:00Z","timestamp":1784851200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100005156","name":"Alexander von Humboldt-Stiftung","doi-asserted-by":"publisher","award":["3.4 - 1071930 - KEN \u2013 IP"],"award-info":[{"award-number":["3.4 - 1071930 - KEN \u2013 IP"]}],"id":[{"id":"10.13039\/100005156","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>\n                    The excessive and often unregulated use of antibiotics in livestock production and human health has led to the dissemination of antibiotic residues and antibiotic resistance genes (ARGs) posing a serious threat to the environment and public health. This study investigates the co-occurrence and spatial distribution of antibiotic residues and ARGs in livestock manure and agricultural soils from Machakos, Kiambu, and Kajiado counties in Kenya, regions characterized by intensive livestock farming. A total of 180 animal manure and soil samples from 30 farms across the three counties were collected and pooled into 18 samples. Antibiotic residues were extracted and quantified using high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS\/MS). Nine ARGs (\n                    <jats:italic>aadA, ermB<\/jats:italic>\n                    ,\n                    <jats:italic>sul1, tetQ, tetW, dfrA1, blaMOX, blaOXA<\/jats:italic>\n                    and\n                    <jats:italic>qnrB<\/jats:italic>\n                    were quantified via absolute and relative qPCR, normalized to\n                    <jats:italic>16S rRNA<\/jats:italic>\n                    gene copy numbers. Multivariate analyses, including PCoA and Spearman Correlation, were conducted to explore ARG structure and co-occurrence. Tetracycline, particularly oxytetracycline, was the most abundant antibiotic in manure (up to 1150 ng mL\n                    <jats:sup>\u22121<\/jats:sup>\n                    ), especially in pig manure from Kiambu. Sulfadimethoxine was undetectable in nearly all samples except in soil mixed with pig manure from Kajiado county, which showed a concentration above 70 ng mL\n                    <jats:sup>\u22121<\/jats:sup>\n                    , the pig manure from the same county had levels below 2 ng mL\n                    <jats:sup>\u22121<\/jats:sup>\n                    . Sulfadimidine, sulfamethoxanole and erythromycin were not detected in any of the samples. A three-way ANOVA showed that animal source (cattle, pigs, poultry) and sample type (manure, soil) were generally not significant factors for antibiotic concentration. Only oxytetracycline (P\u2009=\u20090.0421, 0.0901) and sulfadimethoxine (P\u2009=\u20090.0904, 0.044, 0.054) showed marginal significance by sample type (P\u2009=\u20090.0785). Antibiotic resistance genes were widely distributed,\n                    <jats:italic>with aadA, ermB<\/jats:italic>\n                    and\n                    <jats:italic>sul1<\/jats:italic>\n                    being the most prevalent, especially in soils from Kiambu and Machakos. The\n                    <jats:italic>tetQ<\/jats:italic>\n                    showed extremely high relative abundance, indicating intense selection pressure from tetracyclines. Strong positive correlations were observed between co-occurring ARGs, including\n                    <jats:italic>tetQ<\/jats:italic>\n                    and\n                    <jats:italic>tetW<\/jats:italic>\n                    as well as\n                    <jats:italic>erm<\/jats:italic>\n                    and\n                    <jats:italic>sul1<\/jats:italic>\n                    . The concurrent detection of persistent antibiotic residues and high ARG loads in both manure and soils underscores the urgent need for improved antibiotic stewardship, sustainable manure management, and environmental monitoring in Kenyan agroecosystems.\n                  <\/jats:p>","DOI":"10.1371\/journal.pone.0337311","type":"journal-article","created":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T17:25:59Z","timestamp":1784913959000},"page":"e0337311","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Co-occurrence of antibiotic residues and Antimicrobial resistance genes in animal manure and agricultural soils from Machakos, Kiambu, and Kajiado Counties, Kenya"],"prefix":"10.1371","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3456-611X","authenticated-orcid":true,"given":"Richard M.","family":"Machoka","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Florence","family":"Ng\u2019ong\u2019a","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christabel","family":"Muhonja","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Heshborne","family":"Tindih","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zachary","family":"Getenga","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S\u00f6ren","family":"Thiele-Bruhn","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,7,24]]},"reference":[{"issue":"4","key":"pone.0337311.ref001","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1093\/jacamr\/dlaf117","article-title":"JAC- Antimicrobial Resistance High abundance of antimicrobial resistance genes in chicken flocks receiving antimicrobial treatment in Vietnamese poultry production","volume":"7","author":"A Dutta","year":"2025","journal-title":"JAC-Antimicrob Resist"},{"issue":"5","key":"pone.0337311.ref002","doi-asserted-by":"crossref","DOI":"10.1136\/bmjgh-2021-008159","article-title":"Taking stock of global commitments on antimicrobial resistance","volume":"7","author":"S Tejpar","year":"2022","journal-title":"BMJ Glob Health"},{"key":"pone.0337311.ref003","first-page":"3589","article-title":"Antimicrobial Resistance Rates and Surveillance in Sub-Saharan Africa: Where Are We Now?","volume":"15","author":"S Kariuki","year":"2022","journal-title":"Antimicrobial Resistance Rates and Surveillance in Sub-Saharan Africa\u00a0: Where Are We Now? 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