{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T15:51:34Z","timestamp":1786117894191,"version":"build-2736575974"},"reference-count":45,"publisher":"American Society for Microbiology","issue":"8","license":[{"start":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T00:00:00Z","timestamp":1785801600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T00:00:00Z","timestamp":1785801600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"DOI":"10.13039\/501100004587","name":"Instituto de Salud Carlos III","doi-asserted-by":"publisher","award":["PI19\/00478"],"award-info":[{"award-number":["PI19\/00478"]}],"id":[{"id":"10.13039\/501100004587","id-type":"DOI","asserted-by":"publisher"}]},{"name":"SOCIEDAD GENERAL DE AGUAS DE BARCELONA, S.A.U.","award":["N1"],"award-info":[{"award-number":["N1"]}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["Microbiol Spectr"],"published-print":{"date-parts":[[2026,8,4]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      The World Health Organization classifies extended-spectrum beta-lactamase (ESBL) and carbapenemase-producing\n                      <jats:italic toggle=\"yes\">Klebsiella pneumoniae<\/jats:italic>\n                      as critical-priority pathogens due to their high incidence, mortality, transmissibility, rapid resistance acquisition, and limited treatment options. Beyond clinical settings, their detection in wastewater treatment plants (WWTPs) provides an opportunity to assess their prevalence, persistence, and circulation within wastewater systems. This study characterized 37 antibiotic-resistant\n                      <jats:italic toggle=\"yes\">K. pneumoniae<\/jats:italic>\n                      -related species strains isolated from two WWTPs in the metropolitan area of Barcelona, analyzing their antimicrobial resistance (AMR) profiles, antimicrobial resistance genes (ARGs), biocide and heavy metal tolerance genes (HMTGs), virulence factor genes (VFGs), biofilm-forming capacity, and conjugation ability. Among them, 70.3% were multidrug-resistant (MDR), and 16.2% were extensively drug-resistant. Whole-genome sequencing revealed diverse ARGs; all strains carried \u03b2-lactam resistance genes (14 ESBL and 12 carbapenemase producers), nearly all (96.9%) carried biocide or HMTGs, 64.9% harbored integrases, and all carried VFGs. Core-genome SNP analysis identified closely related strains across sampling periods and treatment stages, suggesting long-term persistence within the wastewater treatment system, despite biological and chemical processes in secondary treatment. Most strains (67.6%) displayed biofilm-forming capacity, and conjugation assays confirmed horizontal gene transfer in five of the seven ESBL-producing strains tested. High-risk clones were predominantly detected in the IFAS secondary treatment stage of the Gav\u00e0-Viladecans WWTP. The three strains recovered from the reclaimed water of the Baix Llobregat WWTP were ESBL or carbapenemase producers. Altogether, these results provide genomic and phenotypic evidence of the persistence and circulation of antibiotic-resistant\n                      <jats:italic toggle=\"yes\">K. pneumoniae<\/jats:italic>\n                      -related species within wastewater treatment systems.\n                    <\/jats:p>\n                    <jats:sec>\n                      <jats:title>IMPORTANCE<\/jats:title>\n                      <jats:p>\n                        WWTPs are essential for urban sanitation and environmental protection. Understanding how clinically relevant pathogens, such as ESBL and carbapenemase-producing\n                        <jats:italic toggle=\"yes\">K. pneumoniae<\/jats:italic>\n                        -related species strains\n                        <jats:italic toggle=\"yes\">,<\/jats:italic>\n                        behave in these settings may inform public health considerations. Investigating the presence and persistence of high-risk MDR pathogens in WWTPs helps identify circulation of AMR, assess the risk of gene transfer, and evaluate the potential for co-selection with other contaminants. This knowledge supports efforts to improve wastewater treatments, strengthen environmental surveillance, and develop integrated One Health strategies to limit the spread of AMR across human, animal, and environmental sectors.\n                      <\/jats:p>\n                    <\/jats:sec>\n                  <\/jats:sec>","DOI":"10.1128\/spectrum.00621-26","type":"journal-article","created":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T01:19:26Z","timestamp":1782868766000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Emergence and persistence of ESBL- and carbapenemase-producing\n                    <i>Klebsiella pneumoniae<\/i>\n                    -related species in Barcelona wastewater treatment plants"],"prefix":"10.1128","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1089-600X","authenticated-orcid":false,"given":"Victoria","family":"Ball\u00e9n","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/03hjgt059","id-type":"ROR","asserted-by":"publisher"}],"name":"ISGlobal","place":["Barcelona, Spain"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karol","family":"Delgado","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/03hjgt059","id-type":"ROR","asserted-by":"publisher"}],"name":"ISGlobal","place":["Barcelona, Spain"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna","family":"Pinar-M\u00e9ndez","sequence":"additional","affiliation":[{"name":"Aig\u00fces de Barcelona, Empresa Metropolitana de Gesti\u00f3 del Cicle Integral de l\u2019Aigua","place":["Barcelona, Spain"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carles","family":"Vilar\u00f3","sequence":"additional","affiliation":[{"name":"Aig\u00fces de Barcelona, Empresa Metropolitana de Gesti\u00f3 del Cicle Integral de l\u2019Aigua","place":["Barcelona, Spain"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-4208-8884","authenticated-orcid":true,"given":"Bel\u00e9n","family":"Galofr\u00e9","sequence":"additional","affiliation":[{"name":"Aig\u00fces de Barcelona, Empresa Metropolitana de Gesti\u00f3 del Cicle Integral de l\u2019Aigua","place":["Barcelona, Spain"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0405-2305","authenticated-orcid":true,"given":"Sara","family":"Mart\u00ed","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00epner96","id-type":"ROR","asserted-by":"publisher"}],"name":"Microbiology Department, Hospital Universitari Bellvitge, IDIBELL-UB","place":["L\u2019Hospitalet de Llobregat, Spain"]},{"name":"Research Network for Respiratory Diseases (CIBERES), ISCIII","place":["Madrid, Spain"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8326-1307","authenticated-orcid":true,"given":"Aida","family":"Gonz\u00e1lez-D\u00edaz","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00epner96","id-type":"ROR","asserted-by":"publisher"}],"name":"Microbiology Department, Hospital Universitari Bellvitge, IDIBELL-UB","place":["L\u2019Hospitalet de Llobregat, Spain"]},{"name":"Research Network for Respiratory Diseases (CIBERES), ISCIII","place":["Madrid, Spain"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manuel","family":"Alcalde-Rico","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/03yxnpp24","id-type":"ROR","asserted-by":"publisher"}],"name":"CSIC, Universidad de Sevilla, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen Macarena","place":["Seville, Spain"]},{"id":[{"id":"https:\/\/ror.org\/00ca2c886","id-type":"ROR","asserted-by":"publisher"}],"name":"CIBER Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III","place":["Madrid, Spain"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9507-105X","authenticated-orcid":true,"given":"Sara M.","family":"Soto","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/03hjgt059","id-type":"ROR","asserted-by":"publisher"}],"name":"ISGlobal","place":["Barcelona, Spain"]},{"id":[{"id":"https:\/\/ror.org\/00ca2c886","id-type":"ROR","asserted-by":"publisher"}],"name":"CIBER Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III","place":["Madrid, Spain"]},{"id":[{"id":"https:\/\/ror.org\/021018s57","id-type":"ROR","asserted-by":"publisher"}],"name":"Faculty of Medicine and Health Sciences, University of Barcelona (UB)","place":["Barcelona, Spain"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_4_2_2","unstructured":"World Health Organization. 2023. 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