Pentadecanoic acid against Candida albicans-Klebsiella pneumoniae biofilm: towards the development of an anti-biofilm coating to prevent polymicrobial infections

The ability to form biofilms is a common feature of microorganisms, which can colonize a variety of surfaces, such as host tissues and medical devices, resulting in infections highly resistant to conventional drugs. This aspect is particularly critical in polymicrobial biofilms involving both fungi and bacteria, therefore, to eradicate such severe infections, new and effective anti-biofilm strategies are needed. The efficacy of pentadecanal and pentadecanoic acid as anti-biofilm agents has been recently reported against different bacterial strains. Their chemical similarity with diffusible signal factors (DSFs), plus the already known ability of fatty acids to act as anti-biofilm agents, suggested to explore their use against Candida albicans and Klebsiella pneumoniae mixed biofilm. In this work, we demonstrated the ability of both molecules to prevent the formation and destabilize the structure of the dual-species biofilm. Moreover, the pentadecanoic acid anti-biofilm coating, previously developed through the adsorption of the fatty acid on polydimethylsiloxane (PDMS), was proved to prevent the polymicrobial biofilm formation in dynamic conditions by confocal laser scanning microscopy analysis. Finally, the evaluation of the expression levels of some biofilm-related genes of C. albicans and K. pneumoniae treated with pentadecanoic acid provided some insights into the molecular mechanisms underpinning its anti-biofilm effect.

Airway fire during awake tracheostomy using high-flow nasal oxygen

High-flow nasal oxygen is increasingly used in complex head and neck surgical procedures and difficult airway management. We describe a case where an operating room fire occurred while using high-flow nasal oxygen during an awake tracheostomy for an obese patient in airway extremis due to supraglottitis. Shortly after the operation began, and before incision of the trachea, electrical diathermy applied to bleeding sub-cutaneous vessels ignited a small flame. This was extinguished without harm to the patient and the procedure was completed without further complication. Fire requires three components: fuel; heat; and an oxidiser. We speculate that high-flow oxygen channelled under the drapes and acted as the oxidiser; either tissue eschar or vapourised fat were the fuel; and the diathermy supplied a source of ignition to complete the fire triad. When using high flows of concentrated oxygen, practitioners should aim to minimise all of these factors and be alert for the risk of fire at every stage of the operation.