{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T01:33:52Z","timestamp":1787016832558,"version":"build-2736575974"},"reference-count":61,"publisher":"American Society for Microbiology","issue":"7","license":[{"start":{"date-parts":[[2025,7,29]],"date-time":"2025-07-29T00:00:00Z","timestamp":1753747200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2025,7,29]],"date-time":"2025-07-29T00:00:00Z","timestamp":1753747200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["mSphere"],"published-print":{"date-parts":[[2025,7,29]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      The global rise of antimicrobial resistance is a major public health threat, with\n                      <jats:italic toggle=\"yes\">Escherichia coli<\/jats:italic>\n                      facilitating the spread of extended-spectrum beta-lactamase (ESBL) genes like\n                      <jats:italic toggle=\"yes\">bla<\/jats:italic>\n                      <jats:sub>CTX-M<\/jats:sub>\n                      , which confer resistance to third-generation cephalosporins (3GCs). This study examines the impact of 3GC treatment on resistant\n                      <jats:italic toggle=\"yes\">E. coli<\/jats:italic>\n                      clones and horizontal gene transfer (HGT) of ESBL genes in broiler chickens in Quito, Ecuador. Fifteen-day-old Ross broilers were divided into three groups: oral ceftriaxone (100 mg\/kg), parenteral ceftriaxone (100 mg\/kg intramuscular), and control (no treatment). The study included three phases: baseline, antimicrobial administration (5 days), and recovery (15 days). Fecal cultures on McConkey agar, with and without ceftriaxone (2 \u00b5g\/mL), measured the ratio of 3GC-resistant lactose fermenters. Regardless of the administration route, ceftriaxone significantly increased resistant coliforms (&gt;80%). Five\n                      <jats:italic toggle=\"yes\">E. coli<\/jats:italic>\n                      colonies per animal and time point were analyzed using single-gene typing, with clonal candidates subjected to whole-genome sequencing. Clonal analysis revealed high genetic diversity, averaging three distinct clones per animal. A unique lineage (H34) emerged exclusively during treatment, and new clones appeared post-treatment. The\n                      <jats:italic toggle=\"yes\">bla<\/jats:italic>\n                      <jats:sub>CTX-M-55<\/jats:sub>\n                      variant was the most abundant ESBL gene, persisting despite fluctuations in other\n                      <jats:italic toggle=\"yes\">bla<\/jats:italic>\n                      <jats:sub>CTX-M<\/jats:sub>\n                      variants. Comparative plasmid analysis suggested\n                      <jats:italic toggle=\"yes\">bla<\/jats:italic>\n                      <jats:sub>CTX-M-55<\/jats:sub>\n                      HGT, as plasmids were identified in two genetically distinct\n                      <jats:italic toggle=\"yes\">E. coli<\/jats:italic>\n                      isolates from the same host. Most plasmids belonged to IncFII, with IncX1 and IncN also present. These findings highlight how 3GC treatments rapidly impact ESBL-producing\n                      <jats:italic toggle=\"yes\">E. coli<\/jats:italic>\n                      diversity in the intestine.\n                    <\/jats:p>\n                    <jats:sec>\n                      <jats:title>IMPORTANCE<\/jats:title>\n                      <jats:p>\n                        The global rise of antimicrobial resistance (AMR) poses a critical public health challenge, with\n                        <jats:italic toggle=\"yes\">Escherichia coli<\/jats:italic>\n                        playing a central role in the spread of extended-spectrum beta-lactamase (ESBL) genes like\n                        <jats:italic toggle=\"yes\">bla<\/jats:italic>\n                        <jats:sub>CTX-M<\/jats:sub>\n                        , which confer resistance to third-generation cephalosporins (3GCs). This study highlights the significant impact of 3GC treatment on the frequency and diversity of 3GC-resistant\n                        <jats:italic toggle=\"yes\">E. coli<\/jats:italic>\n                        clones and horizontal gene transfer of ESBL genes in the intestinal microbiota of broiler chickens. Understanding how antimicrobial treatments drive resistance dynamics in animal populations is crucial for developing strategies to mitigate AMR in both human and veterinary settings.\n                      <\/jats:p>\n                    <\/jats:sec>\n                  <\/jats:sec>","DOI":"10.1128\/msphere.00227-25","type":"journal-article","created":{"date-parts":[[2025,6,27]],"date-time":"2025-06-27T09:00:11Z","timestamp":1751014811000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":3,"title":["Oral and parenteral treatment with a third-generation cephalosporin promotes the proliferation of diverse ESBL-producing\n                    <i>Escherichia coli<\/i>\n                    in the chicken intestinal tract"],"prefix":"10.1128","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-3554-9107","authenticated-orcid":true,"given":"L\u00e1zaro","family":"L\u00f3pez","sequence":"first","affiliation":[{"name":"Instituto de Microbiolog\u00eda, Colegio de Ciencias Biol\u00f3gicas y Ambientales, Universidad San Francisco de Quito","place":["Quito, Ecuador"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Melany","family":"Jumbo","sequence":"additional","affiliation":[{"name":"Instituto de Microbiolog\u00eda, Colegio de Ciencias Biol\u00f3gicas y Ambientales, Universidad San Francisco de Quito","place":["Quito, Ecuador"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pamela","family":"Mosquera","sequence":"additional","affiliation":[{"name":"Instituto de Microbiolog\u00eda, Colegio de Ciencias Biol\u00f3gicas y Ambientales, Universidad San Francisco de Quito","place":["Quito, Ecuador"]},{"id":[{"id":"https:\/\/ror.org\/002kg1049","id-type":"ROR","asserted-by":"publisher"}],"name":"Ingenier\u00eda en Biotecnolog\u00eda, Facultad de Ingenier\u00edas y Ciencias Aplicadas, Universidad de las Am\u00e9ricas","place":["Quito, Ecuador"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gustavo","family":"Donoso","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/04tj63d06","id-type":"ROR","asserted-by":"publisher"}],"name":"Population Health and Pathobiology, North Carolina State University at Raleigh","place":["Raleigh, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jay","family":"Graham","sequence":"additional","affiliation":[{"name":"Environmental Health Sciences Division, University of California","place":["Berkeley, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2617-9021","authenticated-orcid":true,"given":"Gabriel","family":"Trueba","sequence":"additional","affiliation":[{"name":"Instituto de Microbiolog\u00eda, Colegio de Ciencias Biol\u00f3gicas y Ambientales, Universidad San Francisco de Quito","place":["Quito, Ecuador"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_5_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(21)02724-0"},{"key":"e_1_3_5_3_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-024-45154-w"},{"key":"e_1_3_5_4_2","doi-asserted-by":"publisher","DOI":"10.3389\/fmicb.2019.02119"},{"key":"e_1_3_5_5_2","doi-asserted-by":"publisher","DOI":"10.1093\/femsre\/fuac008"},{"key":"e_1_3_5_6_2","doi-asserted-by":"publisher","DOI":"10.1016\/B978-0-12-810477-4.00001-5"},{"key":"e_1_3_5_7_2","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkx146"},{"key":"e_1_3_5_8_2","doi-asserted-by":"publisher","DOI":"10.3390\/biomedicines11112937"},{"key":"e_1_3_5_9_2","doi-asserted-by":"publisher","DOI":"10.1093\/jpids\/pix045"},{"key":"e_1_3_5_10_2","doi-asserted-by":"publisher","DOI":"10.1089\/mdr.2015.0180"},{"key":"e_1_3_5_11_2","doi-asserted-by":"publisher","DOI":"10.1128\/ecosalplus.ESP-0003-2020"},{"key":"e_1_3_5_12_2","doi-asserted-by":"publisher","DOI":"10.1086\/524844"},{"key":"e_1_3_5_13_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.jgar.2022.03.002"},{"key":"e_1_3_5_14_2","doi-asserted-by":"publisher","DOI":"10.1128\/jb.00239-23"},{"key":"e_1_3_5_15_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.celrep.2021.110239"},{"key":"e_1_3_5_16_2","doi-asserted-by":"publisher","DOI":"10.1289\/EHP7729"},{"key":"e_1_3_5_17_2","first-page":"224","article-title":"Pharmacokinetics of intramuscular and nebulized ceftriaxone in chickens","volume":"25","author":"Junge RE","year":"1994","unstructured":"Junge RE, Naeger LL, LeBeau MA, Long CW, Naeger SL. 1994. Pharmacokinetics of intramuscular and nebulized ceftriaxone in chickens. J Zoo Wildl Med 25:224\u2013228.","journal-title":"J Zoo Wildl Med"},{"key":"e_1_3_5_18_2","doi-asserted-by":"publisher","unstructured":"European Parliament. 2019. The EU poultry meat and egg sector: main features challenges and prospects: in-depth analysis. doi:10.2861\/33350","DOI":"10.2861\/33350"},{"key":"e_1_3_5_19_2","unstructured":"Pant DR Chaudhary N Upadhyaya SI. 2015. Isolation and identification of Escherichia coli (E. coli) from children suspecting urinary tract infection (UTI). International Journal of Health Sciences & Research (www.ijhsr.org) 5:163."},{"key":"e_1_3_5_20_2","doi-asserted-by":"publisher","DOI":"10.1128\/JCM.00945-08"},{"key":"e_1_3_5_21_2","unstructured":"Canada. 2014. Chromocult coliform agar the life science business of Merck operates as MilliporeSigma in the the original medium used for the revised ISO 9308-1 (2014): Chromocult coliform agar to be used to detect and enumerate E. coli and coliform bacteria in water"},{"key":"e_1_3_5_22_2","doi-asserted-by":"publisher","DOI":"10.1128\/JCM.01943-07"},{"key":"e_1_3_5_23_2","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkaa345"},{"key":"e_1_3_5_24_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-021-91456-0"},{"key":"e_1_3_5_25_2","doi-asserted-by":"publisher","DOI":"10.1186\/s13059-021-02483-z"},{"key":"e_1_3_5_26_2","doi-asserted-by":"publisher","DOI":"10.1093\/bioinformatics\/btu153"},{"key":"e_1_3_5_27_2","doi-asserted-by":"publisher","DOI":"10.1099\/mgen.0.000685"},{"key":"e_1_3_5_28_2","doi-asserted-by":"publisher","DOI":"10.1093\/bioinformatics\/bty191"},{"key":"e_1_3_5_29_2","doi-asserted-by":"publisher","DOI":"10.1186\/1471-2105-11-595"},{"key":"e_1_3_5_30_2","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4939-9877-7_20"},{"key":"e_1_3_5_31_2","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/gkj014"},{"key":"e_1_3_5_32_2","doi-asserted-by":"publisher","DOI":"10.1099\/mgen.0.000748"},{"key":"e_1_3_5_33_2","doi-asserted-by":"publisher","DOI":"10.1093\/molbev\/mst010"},{"key":"e_1_3_5_34_2","doi-asserted-by":"publisher","DOI":"10.1099\/mic.0.001525"},{"key":"e_1_3_5_35_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-021-22849-y"},{"key":"e_1_3_5_36_2","doi-asserted-by":"publisher","DOI":"10.1099\/mic.0.001369"},{"key":"e_1_3_5_37_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-017-01532-1"},{"key":"e_1_3_5_38_2","doi-asserted-by":"publisher","DOI":"10.1002\/bies.202400164"},{"key":"e_1_3_5_39_2","doi-asserted-by":"publisher","DOI":"10.3390\/pathogens12091150"},{"key":"e_1_3_5_40_2","doi-asserted-by":"publisher","DOI":"10.1098\/rsif.2023.0074"},{"key":"e_1_3_5_41_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.plasmid.2022.102650"},{"key":"e_1_3_5_42_2","doi-asserted-by":"publisher","DOI":"10.1099\/acmi.0.000808.v3"},{"key":"e_1_3_5_43_2","doi-asserted-by":"publisher","DOI":"10.3390\/genes11111239"},{"key":"e_1_3_5_44_2","doi-asserted-by":"publisher","DOI":"10.1128\/JVI.00090-18"},{"key":"e_1_3_5_45_2","doi-asserted-by":"publisher","DOI":"10.4161\/cib.2.4.8289"},{"key":"e_1_3_5_46_2","doi-asserted-by":"publisher","DOI":"10.1111\/cmi.12655"},{"key":"e_1_3_5_47_2","doi-asserted-by":"publisher","DOI":"10.1128\/AEM.04248-13"},{"key":"e_1_3_5_48_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.drup.2023.101036"},{"key":"e_1_3_5_49_2","doi-asserted-by":"publisher","DOI":"10.1038\/s42003-021-01949-x"},{"key":"e_1_3_5_50_2","doi-asserted-by":"publisher","DOI":"10.1128\/spectrum.02504-23"},{"key":"e_1_3_5_51_2","doi-asserted-by":"publisher","DOI":"10.1080\/17460913.2025.2459526"},{"key":"e_1_3_5_52_2","doi-asserted-by":"publisher","DOI":"10.1128\/mbio.03340-21"},{"key":"e_1_3_5_53_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-020-18668-2"},{"key":"e_1_3_5_54_2","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkz349"},{"key":"e_1_3_5_55_2","doi-asserted-by":"publisher","DOI":"10.1128\/mBio.00583-18"},{"key":"e_1_3_5_56_2","doi-asserted-by":"publisher","DOI":"10.1111\/1574-6968.12084"},{"key":"e_1_3_5_57_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.vetmic.2020.108643"},{"key":"e_1_3_5_58_2","doi-asserted-by":"publisher","DOI":"10.3390\/ani13010090"},{"key":"e_1_3_5_59_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-024-80943-9"},{"key":"e_1_3_5_60_2","doi-asserted-by":"publisher","DOI":"10.1186\/s13756-020-00847-x"},{"key":"e_1_3_5_61_2","doi-asserted-by":"publisher","DOI":"10.3390\/ani10081264"},{"key":"e_1_3_5_62_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.psj.2025.104858"}],"container-title":["mSphere"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.asm.org\/doi\/pdf\/10.1128\/msphere.00227-25","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.asm.org\/doi\/pdf\/10.1128\/msphere.00227-25","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,7,29]],"date-time":"2025-07-29T13:01:41Z","timestamp":1753794101000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.asm.org\/doi\/10.1128\/msphere.00227-25"}},"subtitle":[],"editor":[{"given":"Krishna","family":"Rao","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2025,7,29]]},"references-count":61,"journal-issue":{"issue":"7","published-print":{"date-parts":[[2025,7,29]]}},"alternative-id":["10.1128\/msphere.00227-25"],"URL":"https:\/\/doi.org\/10.1128\/msphere.00227-25","relation":{},"ISSN":["2379-5042"],"issn-type":[{"value":"2379-5042","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,7,29]]},"assertion":[{"value":"2025-03-31","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-05-29","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-06-27","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e00227-25"}}