Bactericidal Efficiency Of Slightly Acidic Electrolyzed Water Against Salmonella In Layer Houses

Salmonella is an important zoonotic pathogen having a significant economic and health impact on animals and humans worldwide. Salmonellosis is characterized by food poisoning, gastroenteritis and hematosepsis. It is difficult to prevent and control Salmonellosis due to there are a wide variety of Salmonalla and transmission routes. Chemical disinfectants have the disadvantage of pollution and residual problems. Thus, decontamination of Salmonella in laying hen houses using slightly acidic electrolyzed water (SAEW), will provide scientific evidence for prevention and control of Salmonellosis. In our study, Salmonella were isolated and identified by samples collection, bacterial cultivation, biochemical tests, PCR (polymerase chain reaction) and serologic tests. The efficacy of SAEW to inactivate different Salmonella in suspension test, foodborne pathogens and indigenous microbiota on shell eggs, pathogenic microorganism on internal surfaces of layer houses were evaluated. The effectiveness of SAEW in reducing pathogens or bacterial mixtures on stainless surfaces was also evaluated and compared its efficacy with composite phenol solution for reducing total aerobic bacteria in anima transport vehicles. Then the efficacy of SAEW against pathoges on different surfaces was evaluated in a disinfection room using an ultrasonic disinfection system. Finally, the component of available chlorine and bactericidal activity of SAEW produced by different generators were investigated. These results provide the following findings:(1) Feces, dusts and feeds are recognized as the main source of salmonella in laying hen houses. S.enteritidis, S.pullorum, S.dublin, S.calabar and S.papuana are the frequently isolated serovar of Salmonella. The bactericidal efficiency of SAEW increased with increasing ACC, treatment time and temperature.(2) Spraying or immersion shell eggs with SAEW at available chlorine concentration(ACC) of 60-100 mg L-1 significantly reduced the populations of S. enteritidis, E. coli O157.H7, S. aureus, Coliforms, Staphylococci, total aerobic bacteria, and moulds and yeasts on shell eggs, and the difference of disinfection effect between SAEW and acidic electrolyzed water was not significant, whereas the bactericidal activity of SAEW was equivalent to or higher than that of chlorine dioxide and NaCIO solution. SAEW was found to be more effective when used in conjunction with alkaline electrolyzed water, and higher reductions were obtained with the immersion treatment.(3) In the absence of bovine serum albumin, complete inactivation of all S.enteritidis, E.coli and S.aureus, in pure cultures and on cotton fabric surfaces were observed after 2.5 and 5 min treatment with SAEW at 40 mg L-1 of ACC, respectively. The bactericidal efficiency of SAEW increased with increasing ACC and treatment time, but decreased with increasing bovine serum albumin concentration. As compared to tap water, SAEW and povidone iodine significantly reduced microbial populations on each surface of layer house. SAEW at ACC of 60-100 mg L-1 showed higher or equivalent bactericidal efficiency than povidone iodine for total aerobic bacteria, staphylococci, coliforms or yeasts and moulds on the floor, wall, feed trough and egg conveyor belt surfaces.(4) The bactericidal efficiency of SAEW at ACC of 30-90 mg L-1 was higher than or equivalent to that of composite phenol in reducing S.typhimurium, E.coli, S.aureus or bacterial mixtures on stainless steel surfaces. Complete inactivation of pathogens on stainless steel surfaces were observed after treatment with alkaline electrolyzed water followed by SAEW at 50 mg L-1 of ACC for 2 min or alkaline electrolyzed water treatment followed by SAEW treatment at 90 mg L-1 of ACC for 0.5 min. No significant differences in bactericidal efficiency were observed between SAEW and composite phenol for reducing total aerobic bacteria in the vehicles. The bactericidal activity of SAEW increased with increasing available chlorine concentration and spraying time. SAEW was also found to be more effective when used in conjunction with alkaline electrolyzed water.(5) Ultrasonic atomization with SAEW at ACC of 50-150 mg L-1 significantly reduced the population of S.enteritidis, S.typhimurium, E.coli, S.aureus on stainless steel, cotton cloth and rubber surfaces. The reduction of more than 2 log10 CFU cm-2 S.enteritidis or S.typhimurium on cotton cloth and stainless steel surfaces were obtained after treatment with SAEW at ACC of 100 mg L"1 for 4 min, and SAEW at ACC of 150 mg L"1 for 2 min. The bactericidal activity of SAEW increased with increasing available chlorine concentration (ACC) and treatment time, but decreased with increasing bacterial concentration.(6) The HC1O concentration and bactericidal efficiency of SAEW produced by electrolysis of HCl or NaCl and HCl in the electrolytic cell without a diaphragm separation were higher that those produced by electrolysis of NaCl in the electrolytic cell without a membrane with the same ACC. pH affect the HClO concentration and bactericidal activity of electrolyzed water.