1f - Nosocomial outbreak of Ralstonia pickettii linked to internationally distributed sodium chloride products, United Kingdom 2023-2024.

Background : Ralstonia pickettii is an environmental waterborne bacteria known to cause opportunistic infections, with capacity to contaminate healthcare products. In late 2023, UKHSA were informed by Australian counterparts of a Ralstonia pickettii outbreak associated with contaminated saline products. We describe the detection and management of a linked outbreak of Ralstonia pickettii in the UK.

Methods : Case finding was conducted using the national laboratory surveillance system and direct communication with hospitals. Isolates were submitted for whole genome sequencing analysis at the UKHSA national reference laboratory.Investigation comprised trawling questionnaires and targeted product sampling. Investigation and risk mitigation required a muti-stakeholder approach, including direct engagement between the manufacturer and UK medicines regulator.

Results : Between September 2023 and January 2024 three confirmed and two probable cases were identified across the UK at separate hospitals. Confirmed case isolates were genetically indistinguishable from strains isolated in Australia with 0-4 single-nucleotide polymorphism differences over 4,218,213 sites, consistent with a common source.Cases were aged 4 to 63 years (median 51), 3 (60%) cases were male. Confirmed cases all had Ralstonia pickettii isolated from blood cultures, all had clinically significant infections and indwelling lines.Control measures included voluntary recall of the product and accompanying information for healthcare professionals and the public.

Conclusions Ralstonia pickettii is a rare but important cause of healthcare product contamination. Public health institutions should adopt a low threshold for investigation of opportunistic pathogen clusters, including Ralstonia pickettii, with consideration for possible product contamination. Management of contamination events is complicated by global distribution chains; it is important to consider control measures may not be comprehensive. Our experience highlights the importance of intelligence sharing and international collaboration to protect patients and the public.