The effect of volatile anaesthetics on common respiratory pathogens

Abstract

There has been little work on the action of vapours of volatile anaesthetics on respiratory pathogens. Topleyl and Bray2 observed definite bactericidal action of ether vapours on certain micro-organisms including respiratory pathogens. Both these workers used very high concentrations of ether vapour. Most of the subsequent work appears to have been carried out on Esclzericliia coli, Staphylococcus aureus and a number of non-pathogenic b a~t e r i a .~-~ Thus little is known of the effect of volatile anaesthetics on respiratory pathogens at the concentrations used in anacsthesia. This is important for three reasons. Firstly, it ha5 clinical relevance to anaesthesia in patients with severe infection,6 secondly, it might throw light on the antibacterial action of anaesthetic vapours on organisms present on the surface of anaesthetic equipment, a factor which might be responsible for an incidence of postoperatibe pulmonary infection which is much lower than might be expected4 and thirdly, it provides an opportunity to study the effect of anaesthetics at a cellular level by use of a simple biological system in which anaesthetic agents produce measurable functional changes.This paper describes studies of the effect of clinical concentrations of halothane, methoxyflurane and trichloroethylene on the growth of two species of common respiratory pathogens. Material9 and methodsIn the present investigation, two species of respiratory pathogens were selected, namely Streptococcus pneumoniae and Haemophilus injluenzae. The same strains of S . pneumoiziae and H. injlirenzue were used throughout the experiments. These strains were obtained from routine diagnostic work. Preparation of bacterial suspensionColonies from overnight growth of S. yneumoniue and H .

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Anaesthetic Machine and Breathing System Contamination and the Efficiacy of Bacterial/Viral Filters

“…Other workers have suggested that anaesthetic gases may in fact bestow some anti-bacterial properties to the breathing system. Mehta and co-workers 33 demonstrated statistically significant reduction in growth of Staphylococcus pneumoniae and Haemophilus influenzae exposed to clinical concentrations of halothane, trichlorethylene and methoxyflurane when incubated on both blood agar plates and an inert substrate (more relevant to the circumstances of contamination of an anaesthetic machine). Inhibition of bacterial growth was found to be dosedependent.…”