ABSTRACT
The present study was aimed at determining antimicrobial susceptibility by a CLSI standard microdilution testing protocol and detecting the resistance genes of motile Aeromonas species isolated from cultured fish. The importance of the minimum inhibitory concentrations was assessed based on statistically determined epidemiological cut-off values calculated by normalized resistance analysis. Unfortunately, CLSI epidemiological cut-off values are available only for Aeromonas salmonicida, and there is no further detailed data on Aeromonas isolated from aquatic animals. The antimicrobial susceptibilities of pre-identified motile Aeromonas species to florfenicol, tetracycline and sulfamethoxazole were determined by calculating epidemiological cut-off values with fully automated and freely available Excel spreadsheets, applying the normalized resistance interpretation (NRI) method. Furthermore, the presence of the antimicrobial resistance genes floR, tetA, tetB, tetC, tetD, tetE, tetH, sulI, sulII and sulIII was detected by PCR analysis and confirmed by sequence analysis. The presence of up to six different genes (multiple antimicrobial resistance) was determined in the Aeromonas isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: Significance and Impact of the Study: In this study, we investigated phenotypic and genotypic antimicrobial resistance characteristics by a novel method based on epidemiological cut-off values. This is the second comprehensive study on the antimicrobial susceptibility characteristics of Aeromonas species using NRI and epidemiological cut-off values. The present research is related to our previous researches focussed on the identification of motile Aeromonads, their prevalence in relation to different fish lengths, seasons and regions, and covered the investigation of Lactococcus garvieae, Yersinia ruckeri, Flavobacterium spp., Enterobacter spp. and Citrobacter spp.
Subject(s)
Aeromonas salmonicida/drug effects , Anti-Bacterial Agents/pharmacology , Sulfamethoxazole/pharmacology , Tetracycline/pharmacology , Thiamphenicol/analogs & derivatives , Aeromonas salmonicida/genetics , Aeromonas salmonicida/isolation & purification , Animals , Drug Resistance, Bacterial/genetics , Fishes/microbiology , Microbial Sensitivity Tests , Thiamphenicol/pharmacologyABSTRACT
Turkey was the largest rainbow trout producer of the European countries in 2016, and the reason for this production is mainly attributed to its egg and fry production. Flavobacterium psychrophilum cause the highest rates of mortality in the starting to feeding stages of the fish. In the present study, twenty-five F. psychrophilum isolates recovered from rainbow trout, coruh trout and brook trout were analysed by RAPD-PCR, ERIC-PCR, REP-PCR and PCR-RFLP, including 16S rRNA, gyrA and gyrB gene regions and PCR-based serotyping method. The PCR-based molecular analysis showed that the isolates could not be differentiated exactly according to isolation source and geographical region. Most isolates were of type-1 and type-2, and some of them were of type-0 and type-3; in addition, one isolate showed a unique serotype. The combined analysis results showed that F. psychrophilum isolates discriminated as five different genotypes and all isolates were successfully discriminated based on host.
Subject(s)
Fish Diseases/microbiology , Flavobacteriaceae Infections/veterinary , Flavobacterium/genetics , Trout , Animals , DNA Gyrase/analysis , Fisheries , Flavobacteriaceae Infections/microbiology , Flavobacterium/classification , Flavobacterium/physiology , Oncorhynchus mykiss , Polymerase Chain Reaction/veterinary , Polymorphism, Restriction Fragment Length , RNA, Bacterial/analysis , RNA, Ribosomal, 16S/analysis , Serotyping/veterinary , TurkeyABSTRACT
Infectious pancreatic necrosis virus (IPNV) is a common pathogen of rainbow trout (Oncorhynchus mykiss) in Turkey. We found that 455 of 1,676 sample pools tested were IPNV positive. Positive samples were found in all geographical regions where sampling was conducted. Sequence and phylogenetic analyses of VP2 from 30 isolates representing all regions showed that the viruses were highly similar in sequence and grouped within Genogroup 5 (serotype Sp-A2). No correlations between sequences, sampling sites or geographical origins were identified. Although clinical disease was evident in several farms, analyses of the amino acid sequence of VP2 showed that all virus strains harboured the P217 T221 motif, assumed to be associated with low virulence. We conclude that IPNV is prevalent in Turkish rainbow trout farms and that the viruses are very homogenous and likely to be of European origin. Frequent exchange of eggs and live fish within the farming industry may explain the homogeneity of the IPNV.
