Effectiveness of alternative sanitizer treatments for inactivating Piscirickettsia salmonis.
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1
Centro de Investigación Marina Quintay, Facultad de Ecología y Recursos Naturales, Universidad Andrés Bello, Chile
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2
Universidad de Zaragoza, Spain
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3
ADL Diagnostic Chile Ltda., Laboratorio de Diagnóstico y Biotecnología, Chile
The bacterium Piscirickettsia salmonis is the causal agent for salmonid rickettsial septicemia (SRS). SRS is arguably the most important disease affecting farmed salmon in Chile, accounting for annual loses of about US$ 700 million. The process of cleaning and applying disinfectants to inactivate pathogenic agents on potentially contaminated items is a common disease management tool in aquaculture establishments as part of an integral practice in biosecurity. From the experimental studies performed on P. salmonis, antibiotics and all disinfectants commonly used in aquaculture are effective against Piscirickettsia spp. (Fryer et al., 1990; Fryer et al., 1992). However, such effectiveness can be affected in field conditions and therefore, methods that effectively and reliably reduce or eliminate pathogenic bacteria on meat are needed.
In this study, we evaluated the differences between disinfectants types, doses of application and time of action in the elimination of P. salmonis using a quantitative suspension test for the evaluation of bactericidal activity. Eight different postharvest treatments for removal of P. salmonis were examined, including active and inactive chlorine dioxides, glutaraldehyde, hypochlorite disinfectants and detergents, peracetic acid, peroxides and others. A 3 replicate set of each of the sample groups was stored at 20 ºC and 95% relative humidity and retested after 1, 5 and 30 minutes with varying doses. According to the standard protocol, greater than 5.0-log CFU/ml reductions of P. salmonis were considered as a successful reduction. In addition, mean and standard deviation for each product was calculated globally and stratified by dose (ppm) and time (minutes) of application. All paired data were analyzed by nonparametric tests including the Wilcoxon test and McNemar’s test for nominal data. To compare categories, we used the multiple comparison test of Duncan establishing a ranking and classifying disinfectants in a number of subsets (Duncan, 1977). From these results and ranking, the influence of the dose and the application time for each family product was analyzed. Statistically significant differences was set at a p value of 0.05, for all analysis using the statistical software R (R Development Core Team, 2015).
Overall, disinfection using peracetic acid, peroxides, and both active and inactive chlorine dioxides caused significantly (p < 0.05) highest reduction of >7.5 log CFU/ml in samples, respectively, among all other tested sanitizers. The lowest reduction was obtained after disinfection with hypochlorite detergents. As expected, as doses and time of action increase, there was a significant reduction of the overall counts of P. salmonis (Fig. 1). However, at lowest doses, only the paracetic acids showed zero counts. At medium doses, most disinfectants counted zero with the exception of others, hypochlorite disinfectants and detergents. Again, only the paracetic acids showed zero counts at 1 min; increasing time to 5 min resulted in both paracetic acids and peroxides showing zero counts. Results from this study provide evidences that most efficient disinfectants were paracetic acids and peroxides. The interactions between compounds, doses and times are shown in Figure 2. Only the use of peracetic acid, peroxides, glutaraldehyde and active chlorine dioxide were shown to be the most effective for minimizing the load of P. salmonis contaminated on salmon fillets. This study provides the first quantification of the efficacy of several disinfectants that are used in the Chilean salmon industry. The choice of an adequate disinfectant will be key in the success of any biosecurity program aimed to minimize P. salmonis incidence. This is particularly true when considering that P. salmonis that is a major disease affecting the Chilean farmed salmon population.
Acknowledgements
This research was funded by CORFO-INNOVA project No 12BPC2-13531 and a project funded by the Chilean Fund for Scientific and Technological Development (FONDECYT) (Project 3140235). We thank industry representatives that were willing to participate in this project. The Ministerio de Educación of Spain is acknowledged by the FPU/MEC doctorate fellowship for Ana Muniesa.
References
Duncan, D.B., 1977. Citation Classics - Multiple Range and Multiple-F Tests. Curr Contents, 10-10.
Fryer, J.L., Lannan, C.N., Garces, L.H., Larenas, J.J., Smith, P.A., 1990. Isolation of a Rickettsiales-Like Organism from Diseased Coho Salmon (Oncorhynchus-Kisutch) in Chile. Fish Pathol25, 107-114.
Fryer, J.L., Lannan, C.N., Giovannoni, S.J., Wood, N.D., 1992. Piscirickettsia salmonis gen. nov., sp. nov., the causative agent of an epizootic disease in salmonid fishes. Int J Syst Bacteriol42, 120-126.
R Development Core Team, 2015. R: A language and environment for statistical computing., R Foundation for Statistical Computing. Vienna, Austria.
Keywords:
Disinfectants,
Chlorine,
Glutaraldehyde,
Hypochlorite,
Peracetic Acid,
peroxide,
Piscirickettsia salmonis,
Salmon Farming
Conference:
AquaEpi I - 2016, Oslo, Norway, 20 Sep - 22 Sep, 2016.
Presentation Type:
Oral
Topic:
Aquatic Animal Epidemiology
Citation:
Mardones
FO,
Muniesa
A,
Silva
N,
Henriquez
P and
Bustos
P
(2016). Effectiveness of alternative sanitizer treatments for inactivating Piscirickettsia salmonis..
Front. Vet. Sci.
Conference Abstract:
AquaEpi I - 2016.
doi: 10.3389/conf.FVETS.2016.02.00002
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Received:
24 May 2016;
Published Online:
14 Sep 2016.
*
Correspondence:
DVM. Ana Muniesa, Universidad de Zaragoza, ZARAGOZA, ZARAGOZA, Spain, animuni@unizar.es