{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T13:25:39Z","timestamp":1787923539491,"version":"build-2784847793"},"reference-count":31,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T00:00:00Z","timestamp":1787875200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Programa de Apoyo a Proyectos de Investigaci\u00f3n e Innovaci\u00f3n Tecnol\u00f3gica","award":["UNAM-Papiit IF201926"],"award-info":[{"award-number":["UNAM-Papiit IF201926"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>Antimicrobial resistance (AMR) is one of the main public health problems that also affects environmental ecosystems. Sinkholes are understudied groundwater ecosystems that may act as reservoirs and dissemination routes for AMR. This study evaluated the composition, distribution, and antimicrobial resistance profiles of culturable ampicillin-resistant Gram-negative bacteria recovered from sinkholes of the Yucat\u00e1n Peninsula, Mexico. Water samples were collected from 27 sinkholes during dry and rainy seasons. The isolates were identified by MALDI-TOF MS and evaluated by broth microdilution. Representative E. coli isolates were analyzed by whole-genome sequencing. A total of 193 ampicillin-resistant Gram-negative isolates were recovered. The most frequently recovered genera were Enterobacter, Klebsiella, and Escherichia, which were detected across all hydrogeological zones. Resistance to cefotaxime, levofloxacin, gentamicin, and tetracycline was detected among several bacterial genera. Opportunistic bacterial species associated with healthcare-associated infections, including K. pneumoniae, A. baumannii, and P. aeruginosa, were also identified. Genomic analysis of 19 E. coli isolates revealed resistance determinants associated with multiple antimicrobial classes and a diverse population structure dominated by phylogroup B1. These findings show that the Ring of Cenotes aquifer harbors diverse populations of culturable ampicillin-resistant Gram-negative bacteria and emphasize the importance of groundwater ecosystems as environmental reservoirs of AMR.<\/jats:p>","DOI":"10.3390\/microorganisms14091903","type":"journal-article","created":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T12:27:46Z","timestamp":1787920066000},"page":"1903","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Occurrence and Antimicrobial Resistance Profiles of Culturable Ampicillin-Resistant Gram-Negative Bacteria in the Ring of Cenotes Aquifer, Yucat\u00e1n, Mexico"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-6946-0448","authenticated-orcid":false,"given":"Patricia","family":"Vargas-Guti\u00e9rrez","sequence":"first","affiliation":[{"name":"Facultad de Ciencias Biol\u00f3gicas, Doctorado en Ciencias Naturales, Universidad Aut\u00f3noma del Estado de Morelos (UAEM), Cuernavaca 62209, Morelos, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3377-2125","authenticated-orcid":false,"given":"Jos\u00e9 Augusto","family":"Ram\u00edrez-Trujillo","sequence":"additional","affiliation":[{"name":"Centro de Investigaci\u00f3n en Biotecnolog\u00eda, Universidad Aut\u00f3noma del Estado de Morelos (UAEM), Cuernavaca 62209, Morelos, 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Jos\u00e9 Eleuterio Gonz\u00e1lez\u201d, Facultad de Medicina, Universidad Aut\u00f3noma de Nuevo Le\u00f3n, Monterrey 64460, Nuevo Le\u00f3n, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"}]},{"given":"Gabriel","family":"Lizama-Uc","sequence":"additional","affiliation":[{"name":"Unidad de Posgrado e Investigaci\u00f3n, Tecnol\u00f3gico Nacional de M\u00e9xico\/IT M\u00e9rida, Merida 97000, Yucat\u00e1n, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"resources","vocabulary":"credit"}]},{"given":"Ismael","family":"Hern\u00e1ndez-Lucas","sequence":"additional","affiliation":[{"name":"Instituto de Biotecnolog\u00eda, Universidad Nacional Aut\u00f3noma de M\u00e9xico, Cuernavaca 62210, Morelos, 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