Pseudo-outbreak of Bacillaceae species associated with poor compliance with blood culture collection recommendations.

Purpose: This study describes a pseudo-outbreak of Bacillaceae spp. bloodstream infections that spanned five months starting in May 2023 and the infection prevention measures implemented to control it.

Methods: This retrospective study was conducted at a tertiary infectious disease hospital in Bucharest, Romania. An observational audit of the blood culture collection practice in our hospital was performed, and the materials used during blood culture collection were sampled. Bacterial colonies were identified using MALDI Biotyper. The Bacillaceae blood culture positivity rates in the previous four years were compared using the Kruskal‒Wallis rank test.

Results: Bacillaceae spp.-positive blood cultures were recovered from 60 patients over a five-month period. In the case of 58 patients, Bacillaceae spp.-positive blood cultures were considered contaminated. Two patients were treated for Bacillus spp. bacteraemia. The audit revealed significant variation during the preparation of the venipuncture site step and the use of nonsterile medical cotton wool. Medical cotton wool contaminated with species of Bacillaceae was found in 10 out of 12 wards. The control measures included repeated training on the blood culture collection procedure and the removal of Bacillaceae spp.-contaminated cotton wool.

Conclusions: The pseudo-outbreak was caused by the unjustified use of medical cotton wool for disinfection of the skin and blood culture bottle septums. The investigation of this pseudo-outbreak highlighted a gap in blood culture collection practices at our facility and thus allowed for its improvement.