{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T09:26:53Z","timestamp":1785403613952,"version":"3.56.0"},"reference-count":36,"publisher":"American Society for Microbiology","issue":"3","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":["Microbiol Spectr"],"published-print":{"date-parts":[[2026,3,3]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      In recent years, a threatening rise in carbapenem-resistant\n                      <jats:italic toggle=\"yes\">Citrobacter<\/jats:italic>\n                      spp. (CRC) has been observed in various global regions. Sewage systems have repeatedly been suggested as reservoirs. At our tertiary-care hospital in Germany, CRC have become the most frequently detected species among the carbapenem-resistant\n                      <jats:italic toggle=\"yes\">Enterobacterales<\/jats:italic>\n                      (CRE) over the past six years. This study aimed to analyze CRC\u2019s site-specific epidemiological development, assess their clinical significance, and elucidate the potential role of the hospital wastewater system in the observed increase in CRC. A retrospective epidemiological investigation was conducted using Poisson models. Clinical baseline data of affected patients were evaluated. Whole-genome sequencing and a subcluster analysis of 138 CRC patient isolates were performed. The wastewater systems of three clinical wards located in two separate hospital buildings were examined. The annual proportion of CRC in CRE increased from 9.2% in 2019 to 37.8% in 2024 (\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      &lt; 0.001). 27.5% of isolates were detected in clinical specimens, most frequently in urine samples (52.6%). There were no cases of bacteremia. We identified 26 MLST types and 22 subclusters. Ninety-three percent of isolates had one (77.5%), two (14.7%), or three (0.8%) carbapenemases. Wastewater analysis identified 27 of 37 (73.0%) environmental CRC isolates as genetically consistent with patient-derived strains. Our findings reveal a newly emerging complexity, characterized by the spread of various genetically distinct CRC across several departments of our hospital. While CRC colonization increased, the frequency and severity of infections remained moderate. The hospital wastewater system represents a key factor in CRC\u2019s dissemination.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>IMPORTANCE<\/jats:title>\n                    <jats:p>In this study, we analyzed the significant increase in CRC strains at our tertiary-care hospital over the past six years. Our findings revealed that, unlike classical outbreak scenarios \u2014 typically characterized by the clonal expansion of one strain within a single ward or unit \u2014 the rising incidence of CRC was driven by the dissemination of numerous genetically diverse strains across multiple departments. The hospital sewage system was identified as a reservoir and plays an important role in the rapid proliferation and dissemination of CRC. The high complexity of the situation presents a new challenge, as transmission pathways are now difficult to trace, hindering effective prevention. Remarkably, the majority of patients affected by CRC were merely colonized, and severe infections were not observed. It remains to be determined whether this pattern reflects a site-specific phenomenon or indicates a broader trend on a European or even global scale.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1128\/spectrum.02670-25","type":"journal-article","created":{"date-parts":[[2026,1,22]],"date-time":"2026-01-22T14:01:14Z","timestamp":1769090474000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Rising incidence of carbapenem-resistant\n                    <i>Citrobacter<\/i>\n                    spp. in a German tertiary-care hospital: epidemiology, clinical impact, and the role of the hospital wastewater system\u2014findings from a six-year molecular study"],"prefix":"10.1128","volume":"14","author":[{"given":"Helena","family":"Tsakmaklis","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/013czdx64","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Infectious Diseases, 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