{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,3]],"date-time":"2026-11-03T22:56:55Z","timestamp":1793746615491,"version":"4.6.1"},"reference-count":35,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T00:00:00Z","timestamp":1760054400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Objectives: Antimicrobial resistance is a major global health threat. This study aimed to assess the impact of antimicrobial-resistant bacterial pneumonia on in-hospital mortality and length of hospital stay in Spain using a large, nationally representative cohort. Methods: A retrospective cohort study that used data from Spain\u2019s Registry of Specialized Health Care Activity (RAE-CMBD) between 2017 and 2022. Hospitalized adults with bacterial pneumonia were included. Hospitalization episodes with bacterial antimicrobial resistance, defined according to ICD-10-CM codes for antimicrobial resistance (Z16.1, Z16.2), were analyzed versus hospitalization episodes without these codes. Multivariate logistic regression models, adjusted for potential confounders (e.g., age, comorbidity, intensive care unit admission) and sensitivity analyses (Poisson regression and propensity score matching test), were performed. Results: Of the 116,901 eligible hospitalizations, 6017 (5.15%) involved antimicrobial-resistant bacteria. Patients with antimicrobial-resistant bacterial pneumonia were older (median 75 vs. 72 years), had greater comorbidity (Elixhauser\u2013van Walraven index: 8 vs. 5), and were more frequently admitted to the intensive care unit (22% vs. 14%). Crude in-hospital mortality was higher in the antimicrobial resistance group (18.46% vs. 10.05%, p &lt; 0.0001), with an adjusted odds ratio of 1.47 (95% confidence interval, 1.36\u20131.58), p &lt; 0.0001. Length of hospital stay was prolonged in antimicrobial resistance patients (median 14 vs. 8 days; adjusted incident rate ratio of 1.46; 95% confidence interval of 1.41 to 1.50). The most prevalent antimicrobial resistant pathogens were Staphylococcus aureus and Gram-negative bacilli (Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli). Conclusions: Antimicrobial resistance is associated with longer hospital stays and an up to 50% higher risk of mortality. Despite the implementation of control policies in place over the past decade, policymakers must strengthen AMR surveillance and ensure adequate resource allocation. Clinicians, in turn, must reinforce antimicrobial stewardship and incorporate rapid diagnostic tools to minimize the impact of antimicrobial resistance on patient outcomes.<\/jats:p>","DOI":"10.3390\/antibiotics14101006","type":"journal-article","created":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T12:32:47Z","timestamp":1760099567000},"page":"1006","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Impact of Antimicrobial-Resistant Bacterial Pneumonia on In-Hospital Mortality and Length of Hospital Stay: A Retrospective Cohort Study in Spain"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8812-8513","authenticated-orcid":false,"given":"Iv\u00e1n","family":"Oterino-Moreira","sequence":"first","affiliation":[{"name":"Microbiology and Parasitology Department, Faculty of Pharmacy, Complutense University of Madrid, 28040 Madrid, Spain"},{"name":"Pharmacy Department, M\u00f3stoles University Hospital, 28935 M\u00f3stoles, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4505-2958","authenticated-orcid":false,"given":"Montserrat","family":"P\u00e9rez-Encinas","sequence":"additional","affiliation":[{"name":"Pharmacy Department, Alcorc\u00f3n Foundation University Hospital, 28922 Alcorc\u00f3n, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9840-6556","authenticated-orcid":false,"given":"Francisco J.","family":"Candel-Gonz\u00e1lez","sequence":"additional","affiliation":[{"name":"Microbiology Department, San Carlos Clinical Hospital, 28040 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susana","family":"Lorenzo-Mart\u00ednez","sequence":"additional","affiliation":[{"name":"Quality and Patient Management Department, Alcorc\u00f3n Foundation University Hospital, 28922 Alcorc\u00f3n, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,10]]},"reference":[{"key":"ref_1","unstructured":"Directorate-General for Health and Food Safety (2025, August 01). A European One Health Action Plan Against Antimicrobial Resistance (AMR). Available online: https:\/\/health.ec.europa.eu\/publications\/european-one-health-action-plan-against-antimicrobial-resistance-amr_en."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"4653","DOI":"10.2147\/IDR.S283488","article-title":"Multidrug-Resistant and Extensively Drug-Resistant Enterobacteriaceae: Prevalence, Treatments, and Outcomes\u2014A Retrospective Cohort Study","volume":"13","author":"Alkofide","year":"2020","journal-title":"Infect. Drug Resist."},{"key":"ref_3","unstructured":"Antimicrobial Resistance Collaborators (2022). Global burden of bacterial antimicrobial resistance in 2019: A systematic analysis. Lancet Lond. Engl., 399, 629\u2013655."},{"key":"ref_4","unstructured":"Federal Task Force on Combating Antibiotic-Resistant Bacteria (2025, August 01). National Action Plan for Combating Antibiotic-Resistant Bacteria, 2020\u20132025 [Internet], Available online: http:\/\/aspe.hhs.gov\/reports\/national-action-plan-combating-antibiotic-resistant-bacteria-2020-2025."},{"key":"ref_5","unstructured":"Spain Remains on the Front Line Against the Silent Pandemic: Antibiotic Resistance (2025, August 01). Spanish Agency for Medicines and Health Products: Ministry of Health, Available online: https:\/\/www.aemps.gob.es\/informa\/notasinformativas\/laaemps\/espana-mantiene-el-pulso-frente-a-la-pandemia-silenciosa-la-resistencia-a-los-antibioticos\/."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1057","DOI":"10.1016\/S1473-3099(13)70318-9","article-title":"Antibiotic resistance\u2014The need for global solutions","volume":"13","author":"Laxminarayan","year":"2013","journal-title":"Lancet Infect. Dis."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"644","DOI":"10.1093\/cid\/cix411","article-title":"Impact on Morbidity, Mortality, and Length of Stay of Hospital-Acquired Infections by Resistant Microorganisms","volume":"65","year":"2017","journal-title":"Clin. Infect. Dis."},{"key":"ref_8","unstructured":"World Health Organization (2025, August 01). Global Action Plan on Antimicrobial Resistance. Available online: https:\/\/www.who.int\/publications\/i\/item\/9789241509763."},{"key":"ref_9","unstructured":"World Health Organization (2025, August 01). One Health. Available online: https:\/\/www.who.int\/health-topics\/one-health."},{"key":"ref_10","unstructured":"(2025, August 01). One Health Joint Plan of Action (2022\u20132026): Working Together for the Health of Humans, Animals, Plants and the Environment. Available online: https:\/\/www.who.int\/publications\/i\/item\/9789240059139."},{"key":"ref_11","unstructured":"World Health Organization (2024). WHO Bacterial Priority Pathogens List, 2024: Bacterial Pathogens of Public Health Importance to Guide Research, Development and Strategies to Prevent and Control Antimicrobial Resistance, World Health Organization. Available online: https:\/\/www.who.int\/publications\/i\/item\/9789240093461."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1080\/23744235.2024.2390180","article-title":"National trends in pneumonia-related mortality in the United States, 1999\u20132019","volume":"57","author":"Bondarchuk","year":"2024","journal-title":"Infect. Dis."},{"key":"ref_13","unstructured":"(2025, August 01). Underlying Cause of Death, 2018\u20132023, Single Race Results Form, Available online: https:\/\/wonder.cdc.gov\/controller\/datarequest\/D158;jsessionid=3A8160D25E64B52113AD31741CFD#Options."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"487","DOI":"10.1016\/j.mcna.2018.12.008","article-title":"Community-acquired Pneumonia and Hospital-acquired Pneumonia","volume":"103","author":"Lanks","year":"2019","journal-title":"Med. Clin. N. Am."},{"key":"ref_15","unstructured":"(2025, August 01). Global Antimicrobial Resistance and Use Surveillance System (GLASS) Report: 2022. Available online: https:\/\/www.who.int\/publications\/i\/item\/9789240062702."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"415","DOI":"10.1056\/NEJMoa1500245","article-title":"Community-Acquired Pneumonia Requiring Hospitalization among U.S. Adults","volume":"373","author":"Jain","year":"2015","journal-title":"N. Engl. J. Med."},{"key":"ref_17","unstructured":"(2025, August 01). Royal Decree 69\/2015, of February 6, Regulating the Registry of Specialized Healthcare Activities (RAE-CMBD). Available online: https:\/\/www.boe.es\/eli\/es\/rd\/2015\/02\/06\/69."},{"key":"ref_18","unstructured":"Statistical Portal (2025, August 01). Interactive Consultation of the National Health System, Available online: https:\/\/pestadistico.inteligenciadegestion.sanidad.gob.es\/publicoSNS\/N\/rae-cmbd\/rae-cmbd\/informacion-general."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"997","DOI":"10.1136\/thoraxjnl-2013-203384","article-title":"Multidrug-resistant pathogens in hospitalised patients coming from the community with pneumonia: A European perspective","volume":"68","author":"Aliberti","year":"2013","journal-title":"Thorax"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"633","DOI":"10.1378\/chest.08-1357","article-title":"Health-Care-Associated Pneumonia Among Hospitalized Patients in a Japanese Community Hospital","volume":"135","author":"Shindo","year":"2009","journal-title":"Chest"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1393","DOI":"10.1001\/archinte.167.13.1393","article-title":"Health Care\u2013Associated Pneumonia Requiring Hospital Admission: Epidemiology, Antibiotic Therapy, and Clinical Outcomes","volume":"167","author":"Mykietiuk","year":"2007","journal-title":"Arch. Intern. Med."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1186\/s41479-017-0041-2","article-title":"Risk factors for community-acquired pneumonia among adults in Kenya: A case\u2014Control study","volume":"9","author":"Muthumbi","year":"2017","journal-title":"Pneumonia"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"f7450","DOI":"10.1136\/bmj.f7450","article-title":"Converting an odds ratio to a range of plausible relative risks for better communication of research findings","volume":"348","author":"Grant","year":"2014","journal-title":"BMJ"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"16497","DOI":"10.1038\/s41598-021-95852-4","article-title":"Association between mortality and highly antimicrobial-resistant bacteria in intensive care unit-acquired pneumonia","volume":"11","author":"Lakbar","year":"2021","journal-title":"Sci. Rep."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"30","DOI":"10.1016\/S1473-3099(10)70258-9","article-title":"Clinical outcomes of health-care-associated infections and antimicrobial resistance in patients admitted to European intensive-care units: A cohort study","volume":"11","author":"Lambert","year":"2011","journal-title":"Lancet Infect. Dis."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"e0142624","DOI":"10.1128\/aac.01426-24","article-title":"Prevalence and mortality associated with multidrug-resistant infections in adult intensive care units in Argentina (PREV-AR)","volume":"69","author":"Cornistein","year":"2025","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"ofae219","DOI":"10.1093\/ofid\/ofae219","article-title":"Impact of Gram-Negative Bacilli Resistance Rates on Risk of Death in Septic Shock and Pneumonia","volume":"11","author":"Hixon","year":"2024","journal-title":"Open Forum Infect. Dis."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"848","DOI":"10.1017\/ice.2017.83","article-title":"Attributable Mortality of Healthcare-Associated Infections Due to Multidrug-Resistant Gram-Negative Bacteria and Methicillin-Resistant Staphylococcus aureus","volume":"38","author":"Nelson","year":"2017","journal-title":"Infect. Control Hosp. Epidemiol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1128\/AAC.01041-09","article-title":"Attributable Hospital Cost and Length of Stay Associated with Health Care-Associated Infections Caused by Antibiotic-Resistant Gram-Negative Bacteria","volume":"54","author":"Mauldin","year":"2010","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"253","DOI":"10.1002\/phar.2171","article-title":"A Multicenter, Prospective, Observational Study to Determine Predictive Factors for Multidrug-Resistant Pneumonia in Critically Ill Adults: The DEFINE Study","volume":"39","author":"Lat","year":"2019","journal-title":"Pharmacotherapy"},{"key":"ref_31","first-page":"498","article-title":"Impact of Penicillin Allergy Label on Length of Stay and Mortality in Hospitalized Patients through a Clinical Administrative National Dataset","volume":"183","author":"Walter","year":"2021","journal-title":"Int. Arch. Allergy Immunol."},{"key":"ref_32","first-page":"161","article-title":"Incidencia de reacciones adversas a medicamentos en pacientes hospitalizados por COVID-19 a trav\u00e9s del conjunto m\u00ednimo b\u00e1sico de datos","volume":"33","year":"2023","journal-title":"Rev. OFIL"},{"key":"ref_33","first-page":"280","article-title":"Use big data as a source of data for health care quality indicators construction","volume":"160","year":"2023","journal-title":"Med. Clin."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1016\/j.medin.2022.12.002","article-title":"Impact of the \u201cZero Resistance\u201d program on acquisition of multidrug-resistant bacteria in patients admitted to Intensive Care Units in Spain. A prospective, intervention, multimodal, multicenter study","volume":"47","year":"2023","journal-title":"Med. Intensiv. Engl. Ed."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Oterino-Moreira, I., Lorenzo-Mart\u00ednez, S., L\u00f3pez-Delgado, \u00c1., and P\u00e9rez-Encinas, M. (2022). Comparison of Three Comorbidity Measures for Predicting In-Hospital Death through a Clinical Administrative Nacional Database. Int. J. Environ. Res. Public Health, 19.","DOI":"10.3390\/ijerph191811262"}],"container-title":["Antibiotics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6382\/14\/10\/1006\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T13:04:18Z","timestamp":1760101458000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6382\/14\/10\/1006"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,10,10]]},"references-count":35,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2025,10]]}},"alternative-id":["antibiotics14101006"],"URL":"https:\/\/doi.org\/10.3390\/antibiotics14101006","relation":{},"ISSN":["2079-6382"],"issn-type":[{"value":"2079-6382","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,10,10]]}}}