{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T13:34:19Z","timestamp":1785418459710,"version":"3.56.0"},"reference-count":28,"publisher":"American Society for Microbiology","issue":"2","license":[{"start":{"date-parts":[[2026,3,3]],"date-time":"2026-03-03T00:00:00Z","timestamp":1772496000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,3,3]],"date-time":"2026-03-03T00:00:00Z","timestamp":1772496000000},"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":["ASM Case Rep"],"published-print":{"date-parts":[[2026,3,3]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:sec>\n                      <jats:title>Background<\/jats:title>\n                      <jats:p>\n                        Ustekinumab, a monoclonal antibody targeting the p40 subunit of interleukin-12 and interleukin-23, is widely used for immune-mediated diseases such as Crohn\u2019s disease. By modulating Th1 and Th17 pathways, ustekinumab may increase susceptibility to intracellular pathogens. We report the first case of\n                        <jats:italic toggle=\"yes\">Chlamydia psittaci<\/jats:italic>\n                        pneumonia in a patient treated with ustekinumab.\n                      <\/jats:p>\n                    <\/jats:sec>\n                    <jats:sec>\n                      <jats:title>Case Summary<\/jats:title>\n                      <jats:p>\n                        A 27-year-old woman with Crohn\u2019s disease presented with severe community-acquired pneumonia, progressive hypoxemia, and pulmonary embolism 3 weeks after initiating ustekinumab therapy. Despite broad-spectrum antibiotics, clinical improvement was limited. Her exposure history revealed contact with multiple pet birds, several of which died recently. Polymerase chain reaction testing confirmed\n                        <jats:italic toggle=\"yes\">C. psittaci<\/jats:italic>\n                        genotype A infection. Targeted treatment with doxycycline led to clinical recovery. Ustekinumab therapy was temporarily postponed.\n                      <\/jats:p>\n                    <\/jats:sec>\n                    <jats:sec>\n                      <jats:title>Conclusion<\/jats:title>\n                      <jats:p>\n                        This case highlights a potential association between ustekinumab and susceptibility to\n                        <jats:italic toggle=\"yes\">C. psittaci<\/jats:italic>\n                        , a zoonotic intracellular pathogen. It underscores the importance of exposure history and considering atypical pathogens in immunocompromised patients. Clinicians should maintain vigilance for opportunistic infections in individuals receiving targeted biologic therapies.\n                      <\/jats:p>\n                    <\/jats:sec>\n                  <\/jats:sec>","DOI":"10.1128\/asmcr.00129-25","type":"journal-article","created":{"date-parts":[[2026,1,9]],"date-time":"2026-01-09T14:00:19Z","timestamp":1767967219000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":1,"title":["<i>Chlamydia psittaci<\/i>\n                    pneumonia in a patient using ustekinumab therapy for Crohn\u2019s disease"],"prefix":"10.1128","volume":"2","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1961-9589","authenticated-orcid":false,"given":"J. A. M. C.","family":"Dirks","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/03bfc4534","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Medical Microbiology (and reference laboratory for human Chlamydia infections from animal origin), Zuyderland Medical Center","place":["Sittard-Geleen, the Netherlands"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"L.","family":"Mulder","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/03bfc4534","id-type":"ROR","asserted-by":"publisher"}],"name":"Pulmonology Department, Zuyderland Medical Center","place":["Heerlen, the Netherlands"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K.","family":"Burgers","sequence":"additional","affiliation":[{"name":"Department of Sexual Health, Infectious Diseases and Environmental Health, Public Health Service South Limburg","place":["Heerlen, the Netherlands"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4007-6985","authenticated-orcid":true,"given":"J. G. M. C.","family":"Damoiseaux","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/03bfc4534","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Medical Microbiology (and reference laboratory for human Chlamydia infections from animal origin), Zuyderland Medical Center","place":["Sittard-Geleen, the Netherlands"]},{"id":[{"id":"https:\/\/ror.org\/02jz4aj89","id-type":"ROR","asserted-by":"publisher"}],"name":"Central Diagnostic Laboratory, Maastricht University Medical Center","place":["Maastricht, the Netherlands"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5199-4226","authenticated-orcid":true,"given":"E. R.","family":"Heddema","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/03bfc4534","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Medical Microbiology (and reference laboratory for human Chlamydia infections from animal origin), Zuyderland Medical Center","place":["Sittard-Geleen, the Netherlands"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.280.5368.1432"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.280.5368.1435"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.2146\/ajhp160010"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.arbres.2020.11.008"},{"key":"e_1_3_2_6_2","unstructured":"(SWAB). D.W.P.o.A.P. 2024. 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Psittacosis. In StatPearls. Treasure Island (FL), StatPearls Publishing."},{"key":"e_1_3_2_19_2","doi-asserted-by":"publisher","DOI":"10.3389\/fphys.2023.1132724"},{"key":"e_1_3_2_20_2","doi-asserted-by":"publisher","DOI":"10.2147\/IDR.S435246"},{"key":"e_1_3_2_21_2","doi-asserted-by":"publisher","DOI":"10.3389\/fimmu.2022.929213"},{"key":"e_1_3_2_22_2","doi-asserted-by":"publisher","DOI":"10.1001\/jamadermatol.2021.2599"},{"key":"e_1_3_2_23_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.cgh.2020.01.008"},{"key":"e_1_3_2_24_2","doi-asserted-by":"publisher","DOI":"10.3389\/fphar.2024.1475222"},{"key":"e_1_3_2_25_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.cgh.2022.07.032"},{"key":"e_1_3_2_26_2","doi-asserted-by":"publisher","DOI":"10.1186\/s12879-022-07381-8"},{"key":"e_1_3_2_27_2","doi-asserted-by":"publisher","DOI":"10.3389\/fcimb.2023.1084882"},{"key":"e_1_3_2_28_2","doi-asserted-by":"publisher","DOI":"10.1080\/00365540310009707"},{"key":"e_1_3_2_29_2","unstructured":"World Health Organisation. 2024. 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