Improving livestock feed safety and infection prevention: Removal of bacterial contaminants from hay using cold water, bubbles and ultrasound

A proof-of-concept study of the removal of early and late phase biofilm from skin wound models using a liquid acoustic stream

Chronic wounds fail to progress through the normal stages of healing, with the largest remediable cause of chronicity being presence of a multi-species biofilm. Removal of biofilm from the wound environment is central to wound care. A device for mechanically removing biofilms from wounds has been devised. The removal is caused by small-scale liquid currents and shear, generated by acoustically activated microscopic air bubbles. These bubbles and acoustic waves are delivered onto the wound by a gentle liquid stream, allowing cleaning in situ and removal of debris in the run-off liquid. We have investigated if this liquid acoustic wound stream (LAWS) can remove bacterial biofilm from soft biological wound models and studied the effect of LAWS on the cellular tissues of the substrate. LAWS will efficiently remove early Pseudomonas aeruginosa biofilm from an artificial wound in a pig's trotter, 24 hours-mature biofilm of P. aeruginosa from a pre-wounded human full thickness skin model (EpiDerm FT), and 3-day mature biofilm of P. aeruginosa or Staphylococcus aureus from a porcine skin explant. Histological examinations of uninfected EpiDerm models that had been treated by LAWS and then stained with Haematoxylin and Eosin, demonstrated no damage to the human tissue, and wound diameter was smaller in the treated skin models compared with untreated samples. Immunofluorescence staining for cytokeratin 14 showed that keratinocytes had migrated further across the wound in the uninfected samples treated by LAWS. We discuss the implications for wound healing and propose further laboratory and clinical studies to demonstrate the removal of biofilm from patients with chronic leg ulcers and the impact on healing.

The Possibilities of Using Ultrasonically Activated Streams to Reduce the Risk of Foodborne Infection from Salad

In this study, we investigated the effects of an ultrasonically activated stream (UAS) on the removal of microbial contaminants from spinach leaves. The microbial loads on samples cleaned with and without UAS were enumerated using the cell culture method and compared against unwashed samples on day 0 and day 6 after cleaning. The effects of UAS cleaning on leaf quality were also examined through both macroscopic and microscopic inspection, as well as measurement of the electrolyte leakage rate. Results showed that the microbial load on samples cleaned with UAS for 2 min was significantly lower on day 6 after cleaning than on those treated without ultrasound. Comparison between the cleaning effects of UAS for 40 s versus 2 min indicated that a cleaning duration of 2 min allowed sufficient time for UAS to disaggregate and detach the microbial contamination more effectively. In this case, the induction of bacteria into a viable but non-culturable state does not affect the shelf-life test results as much as it does with a 40 s clean. UAS cleaning for 2 min did not produce significant surface damage, which can affect overall leaf quality. These findings highlight the potential of UAS systems in the salad industry to improve the microbiological quality and shelf life of salads.