Abstract:
Introduction: Recent reports implied heater-cooler units (HCU), which are used for warming of infusions, blood or in ECMO devices, as possible origin of healthcare-associated infections (HAIs) with potentially pathogenic bacteria like nontuberculous mycobacteria [1]. This represents a source of contamination in a usually sterile setting. Aim of this study is to analyse water from infusion heating devices (IHDs) for bacterial contamination and to raise the question if IHDs act as a possible source in the transmission of HAIs.
Methods: 300-500 ml of thermal transfer fluid (TTF) derived from the reservoirs of 22 independent IHDs were collected and processed on different selective and non-selective media for colony count and identification of bacteria. Strains of Mycobacterium species (spp.) were further analysed by whole genome sequencing.
Results: Bacterial growth was observed in each of the 22 collected TTFs after cultivation at 22°C and 36°C. Pseudomonas aeruginosa was the most frequent pathogen identified, being present in 13.64% (3/22) at > 100 CFU/100mL. Colonization with Mycobacterium chimaera, Ralstonia pickettii and Ralstonia mannitolilytica was detectable in 9.09% (2/22) of the isolates. Primary sequencing of the detected M. chimaera suggests a close relationship to a M. chimaera strain detected in an outbreak in Switzerland, which led to the death of two patients.
Discussion: A contamination of the TTF represents a germ reservoir in a sensitive setting. Handling errors of the IHD may lead to distribution of opportunistic or facultative bacterial pathogens, increasing the risk of nosocomial infection transmission.
Reference:Schnetzinger M, Heger F, Indra A, Kimberger O. Bacterial contamination of water used as thermal transfer fluid in fluid warming devices. J Hosp Infect. 2023 Jun 27:S0195-6701(23)00203-7. doi: 10.1016/j.jhin.2023.06.018. Epub ahead of print. PMID: 37385452.