Vapour-phase activities of essential oils against antibiotic sensitive and resistant bacteria including MRSA.

AIMS: To determine whether essential oil (EO) vapours could reduce surface and airborne levels of bacteria including methicillin-resistant Staphylococcus aureus (MRSA). METHODS AND RESULTS: The antibacterial activity of geranium and lemongrass EO individually and blended were evaluated over a range of concentrations by direct contact and vapour diffusion. The EO were tested in vitro against a selection of antibiotic-sensitive and -resistant bacteria, including MRSA, vancomycin-resistant Enterococci (VRE), Acinetobacter baumanii and Clostridium difficile. An EO blend containing lemongrass and geranium was used to formulate BioScent that was dispersed into the environment using the ST Pro machine. The effects were variable depending on the methods used. In a sealed box environment, MRSA growth on seeded plates was reduced by 38% after 20 h exposure to BioScent vapour. In an office environment, the ST Pro machine dispersing BioScent effected an 89% reduction of airborne bacteria in 15 h, when operated at a constant output of 100%. CONCLUSIONS: EO vapours inhibited growth of antibiotic-sensitive and -resistant bacteria in vitro and reduced surface and airborne levels of bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Results suggest that EO vapours, particularly Bioscent, could be used as a method of air disinfection.

An inhibitor of the sodium pump obtained from human placenta.

BACKGROUND: Much effort has been expended in the search for an endogenous inhibitor of the cellular sodium/potassium pump, a compound of major physiological importance, which has been implicated in the mechanism of essential hypertension. Others have suggested that ouabain or an isomer of ouabain may be the endogenous pump inhibitor. Neonatal cord serum contains an inhibitor of the sodium pump; we attempted to isolate and characterise this substance from human placentas. METHODS: Homogenised placentas were dialysed and the resulting solutes were trapped on octadecylsilyl silica and then separated by high-performance liquid chromatography. Measurement of the activity of the sodium pump of human leucocytes was used to test each fraction for the presence of the inhibitor. FINDINGS: An inhibitor of the sodium pump was obtained by this technique in a mass spectrometrically pure form with a mass of 370 Da, an empirical formula of C24H34O3 and only one hydroxyl group. The characteristic fragmentation pattern observed in negative-ion mass spectrometry was compared with those of various model compounds; this comparison suggested that the active material was a dihydropyrone-substituted steroid. INTERPRETATION: These results suggest that a dihydropyrone-substituted steroid is an endogenous regulator of the sodium pump in humans and, presumably, other mammals. Proof of the endogenous origin will require the demonstration of a previously unrecognised biosynthetic pathway.

Study of an actinomycin complex by mass spectrometry-mass spectrometry.

The characterization of components within actinomycin complexes may often be complicated by the lack of material and standards of known actinomycins. Mass spectrometry-mass spectrometry can be employed both as a separatory device and as a means of structural analysis. This technique has been applied to an actinomycin complex obtained from a previously unidentified Streptomyces strain. The method involved initial work on a known material, in this case actinomycin D, and application to the unknown material. Three major components within the unknown complex were characterized as actinomycins D, F(8), and F(9).