Nosocomial Outbreak of Ralstonia pickettii Infections Likely Linked to Saline Solutions in Germany from August 2023 to March 2024-Challenges in Medical Product-Related Outbreaks.

In December 2023, the World Health Organization reported an Australian nosocomial Ralstonia pickettii outbreak caused by contaminated saline solutions, causing bloodstream infections. The Antibiotic Resistance Surveillance, a Germany-wide laboratory network, has identified five R. pickettii-bacteraemia cases since August 2023 (0-1 annually 2019-2022), prompting an outbreak investigation to identify the source. We defined a case as 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 to June 2024, we detected 25 cases. For eighteen cases, isolates were available, and sequences from six cases clustered within 6 allelic differences but showed >43 allelic differences from Australian outbreak-associated sequences. These confirmed cases occurred in three hospitals across three federal states between October 2023 and 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 solutions, although no product/lot was confirmed. Tracing products/lots was particularly challenging. Patient-level documentation of medical products/lots and official mandates for the testing of retained samples could improve product traceback in future outbreaks.