Abstract
An electrochemically activated solution (ECAS), generated by electrolysis of a dilute sodium chloride solution in a four-chamber electrolytic cell (Ecas4), was tested as a sanitising aerosol in eliminating bacteria from the environment of a weaning room vacated 24-48h earlier, at a continuous flow pig farm. An ultrasonic humidifier was used to fill the environment with a fog (droplets with diameters of 1–5 μm) containing 0.25 ppm of hypochlorous acid. The weaning room was fogged for 3 min at 30 min intervals during five hours of aerosol disinfection. An innovative sample treatment with propidium monoazide dye in conjunction with cyclonic air sampling was optimised and adapted for discerning live/dead bacteria in subsequent molecular quantification steps. Without fogging, total bacterial load ranged from 5.06 ± 0.04 to 5.75 ± 0.04 Log10 CFU/m3. After the first hour of fogging, a 78% total bacterial reduction was observed, which further increased to > 97% after the second hour, > 99.4% after the third and 99.8% after the fourth hour, finally resulting in a 99.99% reduction from the farm environment over five hours. Unlike the current formaldehyde spray disinfection protocol, which requires a long empty period because of its hazardous properties, this economically viable and environmentally friendly disinfection protocol may significantly lower downtime. Moreover, ECAS fogging can be easily adapted to a variety of applications, including the elimination of pathogens from livestock farm air environment for disease prevention, as well as decontamination after disease outbreaks.
Highlights
Bacterial and/or viral respiratory diseases are a major economic cost for pork production systems
Based on our preliminary data, where Ecas4 anolyte at lower concentrations of free available chlorine (FAC) has shown to be readily quenched by the presence of organic material in Veterinary Fastidious Medium (VFM) and cation-adjusted Mueller-Hinton (CA-MH) broth, a slightly modified Clinical and Laboratory Standards Institute [26] method was used for the kill-time assay
As in previous studies [31,32], the air sampling protocol adopted in this study proved successful in detecting very low levels of A. pleuropneumoniae in the growing/finishing and weaning sheds with pigs present, during the optimisation steps; no A. pleuropneumoniae was isolated from the empty weaning rooms during the fogging experiments
Summary
Bacterial and/or viral respiratory diseases are a major economic cost for pork production systems. In association with vaccination and the use of antibiotics, the prevention of porcine respiratory disease complex has been achieved by managing the environmental stressors through usage of disinfectants such as sodium hypochlorite, hydrogen peroxide, chlorine dioxide, formaldehyde, quaternary ammonium compounds, peroxyacetic acid and iodophors. While all these chemicals are very effective in reducing microbial load, there are limitations including differential effectiveness against a variety of bacteria [8], co-selection of antibiotic resistance [9], corrosiveness [10], concerns with skin irritation, and cross resistance to other disinfectants and antibiotics [11]. To assess the effectiveness of the Ecas fogging technique in decontamination of the emptied weaning room, we optimised an air sampling technique for bacteria detection and quantification using a Coriolis cyclonic air sampler
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