Nosocomial outbreak of Ralstonia picketii in Germany from August 2023 until March 2024

In December 2023, the World Health Organisation reported an Australian nosocomial Ralstonia pickettii outbreak by contaminated saline-solutions, causing bloodstream infections. The Antibiotic Resistance Surveillance, a Germany-wide laboratory network, captured five R. pickettii-bacteraemia cases since August 2023 (0-1 annually 2019-2022), prompting an outbreak investigation to identify the source. Case definition: A person with R. pickettii in any material (possible) or in blood culture (probable), confirmed if in the genetic outbreak cluster. We implemented nationwide R. pickettii surveillance, subjected isolates to core genome-multilocus sequence-typing, and compared cases by exposure, including medical products. From August 2023-June 2024, we detected 25 cases. For 18 cases, isolates were available and sequences from six cases clustered within six allelic differences but showed >43 allelic differences to Australian outbreak-associated sequences. These confirmed cases occurred in three hospitals across three federal states between October 2023-March 2024, linked only by saline-solution exposure. Four products and 11 lots matched across two of three hospitals. Retain sample testing remained negative. The R. pickettii outbreak in Germany was likely linked to saline-solution, although no product/lot was confirmed. Collating and tracing products/lots were major challenges. Patient-level documentation of medical products/lots or ward-level, digitalised purchase lists could help trace medical products in future outbreaks.