Abstract
Background: Evidence to date indicates that heater–cooler units (HCUs) and heater units (HUs) can generate potentially infectious aerosols containing a range of opportunistic pathogens such as Mycobacterium chimaera, other non-tuberculous mycobacterial (NTM) species, Pseudomonas aeruginosa and Legionella spp. Our purpose was to determine the extent of Legionella contamination and total viable count (TVC) in HCUs and HUs and to analyze the relationship by water system design of devices of two different brands (LivaNova vs. Maquet). Methods: Legionella spp. were detected and quantified by our optimized PMA-qPCR protocol; TVCs were assessed according to ISO protocol 6222. Analyses were performed in the first sampling round and after six months of surveillance. Results: Overall, Legionella spp. was detected in 65.7% of devices. In the second sampling round, Legionella positivity rates were significantly lower in water samples from the Maquet devices compared to the LivaNova ones (27.3% vs. 61.5%). LivaNova HCUs also yielded more Legionella, and aquatic bacteria counts than Maquet in both first and second-round samples. Conclusions: We recommend that all surgical patients and staff exposed to aerosols from thermoregulatory devices should be followed up for Legionella infection and that microbiological surveillance on such devices should be conducted regularly as precautionary principle.
Highlights
Legionellae are ubiquitously present in water environments, either natural or man-made
When we analyzed a second water sample taken from the same devices after six months of Legionella spp. was detected in 65.7% of devices, with a slightly higher percentage of monthly disinfection, we found on average a lower total number of contaminated devices (40.0%)
non-tuberculous mycobacterial (NTM) and Legionella spp., poses a potential risk of infection for patients and personnel in operating theatres. This contamination can be mainly ascribed to the presence of waterborne bacteria: the microorganisms in heater–cooler units (HCUs) and heater units (HUs) biofilms primarily originate from tap water when tap water is added to the water tanks of thermoregulatory devices without filtration [49,50], a procedure strongly
Summary
Legionellae are ubiquitously present in water environments, either natural or man-made. Even though these bacteria are usually found at low concentrations in natural aquatic environments, mounting evidence has shown how artificial water environments with particular physical and chemical conditions can favor the growth of these pathogens [1]. Evidence to date indicates that heater–cooler units (HCUs) used during cardiopulmonary bypass surgeries can generate potentially infectious aerosols containing a range of opportunistic pathogens. Evidence to date indicates that heater–cooler units (HCUs) and heater units (HUs) can generate potentially infectious aerosols containing a range of opportunistic pathogens such as Mycobacterium chimaera, other non-tuberculous mycobacterial (NTM) species, Pseudomonas aeruginosa and Legionella spp. Analyses were performed in the first sampling round and after six months of surveillance
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