engleski

Antimicrobial resistance surveillance in Croatian marine farms – preliminary results

ANTIMICROBIAL RESISTANCE SURVEILLANCE IN CROATIAN MARINE FARMS- PRELIMINARY RESULTS D. Oraić*1, S.Zrnčić1, Ž. Mihaljević1, I. Sučec2, T.Veić3, S.Duvnjak1 1Croatian Veterinary Institute, Zagreb, Croatia 2Ministry of Agriculture, Veterinary Directorate, Zagreb, Croatia 3 Faculty of Sciences, University of Zagreb, Croatia *Corresponding author: oraic@veinst.hr Introduction Aquaculture development and intensification as well as international trade are favouring spreading of infectious diseases. One of the most effective ways to control infectious diseases is use of antimicrobial treatment. Inappropriate use of antimicrobials without reliable diagnosis and control of fish health could evoke the problems of bacterial resistance with negative impacts on the effective control of other bacterial agents, to environment and finally to human health (Bondad-Reantaso and al. 2012). There is a possibility of resistance genes transfer and spreading among bacteria in aquatic environment. Apart of spreading of resistance genes, injudicious use of antimicrobials could also result in occurrence of residues in aquaculture products, resulting in unacceptable quality of the seafood and economic losses in the aquaculture sector. Since the diseases occur in well managed aquaculture facilities, antimicrobials usage is inevitable but the special care should be put in place to avoid the antimicrobial resistance development (Cabello, 2006). Croatian mariculture industry is developing business with increasing quantities of cultivated European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata).Health problems during the cultivation cycle are almost the same as in other Mediterranean countries and in cooperation with Ministry of Agriculture, Veterinary Directorate, a one year surveillance program, with aim to get a preliminary insight in susceptibility of bacterial pathogens was conceived. Sensitivity of the most devastating bacterial pathogensVibrio anguillarum andTenacibaculum maritimum, recovered from infected sea bass and sea bream to most often administered antimicrobials, was tested and evaluated. Material and methods Specimen collected during the disease outbreaks were collected and submitted to the laboratory for diagnostics. External examination and necropsy were performed prior isolation of bacteria from external lesion and internal organs on the appropriate media like Marine agar (Franse et al., 2011) and FMM, Flexibacter maritimum medium (Pazos et al. 1996). Pure cultures were identified by determination of biochemical properites using phenotypic test (API). The identification was confirmed by PCR using specific primers sets encoding amiB gene for V. anguillarum (Xiao et al., 2009) and MAR1 and MAR2 for T. maritimum (Avendano-Herrera et al., 2004). Susceptibility to antimicrobials (potentiated sulphonamids, oxytetracycline, quinolons, florphenicol and erythromycin) was tested using disc diffusion method and broth dilution method with aim to determine minimal inhibitory concentrations (Alderman and Smith, 2001). Statistical analysis of the obtained results was performed. Results Prevalence of both bacterial species was detected as moderate with empahisis on coinfection during early spring connected to the increase of the water temperature in sea bass. Sometimes, samples of sick fish were submitted after unsuccessful treatment and usually resistence was detected to oxytetracycline and potentiated sulphonamides, two more often used antimicrobials. In the paper statistical analysis with comparison of the results obtained as results of both methods will be presented. It could be concluded that more efforts should be put to create comprehensive prophylactic programme as a part of the technological protocol of cultivation of both Mediterranean species. References Alderman, D.J., P. Smith. 2001. Development of draft protocols of standard reference methods for antimicrobial agent susceptibility testing of bacteria associated with fish diseases. Aquaculture, 196, :211–243. Austin, B., D.A.Austin. 1989. Methods for the microbiological examination of fish and shellfish. Chichester, UK. Ellis Horwood. Avendaño-Herrera, R., B.Margarinos, A.E.Toranzo, R.Beaz, J.L.Romalde. 2004. Species-specific polymerase chain reactionprimer sets for the diagnosis of Tenacibaculummaritimum infection. Diseases of Aquatic Organisms, 62:75-83. Bondad-Reantaso, M.G., J.R.Arthur, R.P.Subasinghe, eds. 2012. Improving biosecurity through prudent and responsible use of veterinary medicines in aquatic food production. FAO Fisheries and Aquaculture Technical Paper. No. 547. Rome, FAO. 207 pp. Cabello, F.C. 2006. Heavy use of prophylactic antibiotics in aquaculture: a growing problem for human and animal health and for the environment. Environmental Microbiology, 8: 1137–1144. Frans, I., D.W.Michiels, P.Bossier, K.A.Willems, B. Lievens, H.Rediers (2011) Vibrio anguillarum as a fish pathogen: virulence factors, diagnosis and prevention. Journal of Fish Diseases, 34, 643-661. Pazos, F., Y.Santos, A.R.Macias, S.Nuñez, A.E.Toranzo. 1996. Evaluation of media for the successful culture of Flexibactermaritimus. Journal of Fish Diseases, 19:193–197 Xiao P., Mo Z.L., Mao Y.X., Wang C.L., Zou Y.X. & Li J.2009.Detection of Vibrio anguillarum by PCR amplification of the empAgene. Journal of Fish Diseases, 32: 293–296.

bacterial diseases, sea bass, antibacterial sensitivity

nije evidentirano