Male endotracheal tubes with an inner diameter of 9.5 mm and length of 33 cm were contaminated with a suspension of 10^6 CFU/ml of a clinical isolate of a methicillin–resistant Staphylococcus aureus (MRSA). The male tubes were completely filled with the suspension. The UVC light guide was inserted and the ends of the ET tube were sealed with plugs. Holes were drilledthrough the ET tube wall for sampling purposes. The reference measurements were a 100 μL sample from the sampling hole before the UVC light source was switched on. Samples were drawn after 5, 10, 15, 20, 25 and 30 minutes of UVC treatment from three ET tubes. After plated and incubated overnight the number of colonies was counted. A log 6 reduction is observed after 20 minutes of UVC exposure, see results below.
The figure above shows the result of the UVC disinfection of the MRSA in the male ET tubes. At left diluted samples after 5 minutes of UVC exposure (two first columns). Next undiluted samples collected and plated after 10, 15, 20, 25 and 30 minutes UVC exposure.
In the figure below the counts observed on the plates shown above are plotted as log survival as a function of UVC dose expressed in minutes of exposure with the UVC light source.Leave a reply