Aims: This study aimed to isolate and characterize putative new probiotic with antimicrobial properties against common fish pathogens from the gut of Oreochromis spp. (red tilapia). Methodology and results: A total of 28 colonies were isolated from gut of Oreochromis spp. and characterized phenotypically. Eight isolates were selected for probiotic characterization. Temperature, salinity, pH and bile salt tolerance, antibiotic susceptibility and antimicrobial test against selected fish pathogens (Aeromonas hydrophila, Edwardsiella tarda and Staphylococcus aureus subsp. aureus ATCC 25923) were conducted. Characterization studies revealed isolates suited for freshwater environment and exhibited tolerance against wide range of salinity, pH and bile salt. Isolates displayed different antibiotic susceptibility profile, with six exhibited antimicrobial properties against E. tarda. Molecular identification based on 16S rRNA gene sequencing showed 99.44%, 98.59% and 91.21% sequence similarity with Leuconostoc pseudomesenteroides strain 3832T, Leuconostoc lactis strain KCC202369T and Leuconostoc mesenteroides strain 4332T, respectively as compared to known sequence in the GenBank. When identified Leuconostoc spp. were coated on feed pellets, no major decrease in viability over 21 days of storage at 4 °C were observed, with an average of 8 log CFU/mL. Conclusion, significance and impact of study The characterized species allow further application assessment of the probiotic-supplemented tilapia feed. Host-originated Leuconostoc displayed potential antimicrobial properties against fish pathogen E. tarda. The isolates Leuconostoc is expected to provide protective effect for Oreochromis spp. against edwardsiellosis and to exert beneficial effects more efficiently as compared to commercial probiotics which are not specifically target for Oreochromis spp., thereby indirectly helping fish farmers in achieving economic sustainability and increase affordability of fish.
Leuconostoc ; Anti-Infective Agents ; Tilapia ; Edwardsiella tarda--pathogenicity ; Probiotics

Edwardsiella (E.) ictaluri is a major bacterial pathogen that affects commercially farmed striped catfish (Pangasius hypothalamus) in Vietnam. In a previous study, 19 strains of E. ictaluri collected from striped catfish were biochemically identified with an API-20E system. Here, the same 19 strains were used to assess the ability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS; applied using a MALDI Biotyper) to conduct rapid, easy and accurate identification of E. ictaluri. MALDI-TOF MS could directly detect the specific peptide patterns of cultured E. ictaluri colonies with high (> 2.0, indicating species-level identification) scores. MALDI Biotyper 3.0 software revealed that all of the strains examined in this study possessed highly similar peptide peak patterns. In addition, electrophoresis (SDS-PAGE) and subsequent immuno-blotting using a specific chicken antibody (IgY) against E. ictaluri revealed that the isolates had highly similar protein profiles and antigenic banding profiles. The results of this study suggest that E. ictaluri isolated from striped catfish in Vietnam have homologous protein compositions. This is important, because it indicates that MALDI-TOF MS analysis could potentially outperform the conventional methods of identifying E. ictaluri.
Agriculture ; Asian Continental Ancestry Group* ; Catfishes* ; Chickens ; Edwardsiella ictaluri* ; Edwardsiella* ; Electrophoresis ; Humans ; Mass Spectrometry* ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ; Vietnam

Edwardsiella tarda is a member of the family Enterobacteriaceae, commonly found in tropical and subtropical aquatic environments. Most E. tarda infections are linked to exposure to water or animals that inhabit water. However, it is still an uncommon pathogen in humans and causes mainly watery diarrhea. We describe a case of liver abscess caused by E. tarda. A 60-yr-old Korean man, with underlying diabetes mellitus, had a 10-day stay in Egypt 15 days before presentation. Ultrasound-guided percutaneous transhepatic abscess aspiration was performed. Pus culture revealed E. tarda, which was susceptible to all the antibiotics commonly used against Gram-negative organisms. The patient was treated with cefobactam for 10 days and piperacillin/tazobactam for another 5 days combined with an additional abscess aspiration due to recurrent fever. This therapy led to clinical improvement. The possible source of infection in this case may have been the drinking water supplied during travel in Egypt, but we cannot completely rule out a domestic source, because a liver abscess caused by E. tarda has been reported in a Japanese patient without travel history. Considering the Korean custom of eating raw fish or shrimp, climate changes, and increasing international travel, infections due to E. tarda may increase in Korea. Clinical microbiologists should be aware of this potential pathogen, and prompt investigation of the infection source and site is needed.
Abscess ; Animals ; Anti-Bacterial Agents ; Asian Continental Ancestry Group ; Climate Change ; Diabetes Mellitus ; Diarrhea ; Drinking Water ; Eating ; Edwardsiella ; Edwardsiella tarda ; Egypt ; Enterobacteriaceae ; Fever ; Humans ; Korea ; Liver ; Liver Abscess ; Suppuration ; Water

BACKGROUND: In clinical microbiology the accurate and rapid identification of members of the family Enterobacteriaceae is essential for diagnostic and therapeutic purposes and for epidemiologic studies. Accuracy of identification system depends mainly on data base such as positive rate of biochemical reactions, relative frequency of occurrence of biotype, and isolation frequency of microorganisms. The purpose of this study was to analyze the isolation rate and biotype frequency of the family Enterobacteriaceae isolated from tertiary care hospital in Korea. METHODS: Isolation frequency of the family Enterobacteriaceae isolated from clinical specimens during the period of January 1998 to June 1998 were analyzed. And biochemical phenotypes of 2,022 isolates tested by 10 tube system consisting of 14 conventional biochemical tests were also analyzed. RESULTS: Isolation rate of the family Enterobacteriaceae to the genus level in order of decreasing frequency were Escherichia (37.0%), Serratia (15.9%), Klebsiella (14.9%), Enterobacter (11.1%), Providencia (8.1%), Citrobacter (2.8%), Proteus (2.5%), Morganella (2.4%), Salmonella (2.4%), and Cedecea (0.7%). Among the genus of the family Enterobacteriaceae, Budvicia, Edwardsiella, Ewingella, Hafnia, Kluyvera, Leminorella, Moellerella, Shigella, Tatumella, Xenorhabdus, Yersinia, and Yokenella were not isolated. The number of species and genus of the family Enterobacteriaceae by this study were 48 and 12, respectively. Over 95% of all clinical isolates belonged to only 25 species. CONCLUSIONS: Although these data about frequency of relative isolation rate and biotype patterns of the family Enterobacteriaceae is inadequate according to species and genus, yet these data will be utilized for the application and development of identification method of the family Enterobacteriaceae.
Citrobacter ; Edwardsiella ; Enterobacter ; Enterobacteriaceae* ; Escherichia ; Hafnia ; Humans ; Klebsiella ; Kluyvera ; Korea ; Morganella ; Phenotype ; Proteus ; Providencia ; Salmonella ; Serratia ; Shigella ; Tertiary Healthcare ; Xenorhabdus ; Yersinia

Carp which receive intraperitoneal injections of sodium alginate show a high survival rate after being challenged with Edwardsiella tarda. To elucidate the immunoenhancement by sodium alginate, its effects on the non-specific defense system of carp were investigated. Sodium alginate had little influence either on the activity of the alternative complement pathway or on the phagocytic and respiratory burst activities of head kidney phagocytes (HKP), yet it greatly enhanced the migration of HKP to the peritoneal cavity (the site of injection) and concurrently elevated their phagocytic activity. The number of phagocytes mobilized by sodium alginate was 2 to 50 times greater than that by the well-known peritoneal exudate cell-eliciting agents when injected at the same dose. Accordingly, it is highly probable that the early elimination of challenge bacteria by such mobilized and activated phagocytes was responsible for the high survival rate of the alginateinjected fish. In chemotaxis assays, it was revealed that sodium alginate stimulated sorne leukocyte subpopulation (s) within the peritoneal cavity to produce and/or secrete chemotactic factor (s), while concurrently enhancing the sensitivity of HKP to the factor (s).
Bacteria ; Carps* ; Chemotaxis ; Complement Pathway, Alternative ; Edwardsiella tarda ; Exudates and Transudates ; Head Kidney ; Injections, Intraperitoneal ; Leukocytes ; Peritoneal Cavity ; Phagocytes ; Respiratory Burst ; Sodium* ; Survival Rate

A multiplex PCR protocol was established to simultaneously detect major bacterial pathogens in olive flounder (Paralichthys olivaceus) including Edwardsiella (E.) tarda, Streptococcus (S.) parauberis, and S. iniae. The PCR assay was able to detect 0.01 ng of E. tarda, 0.1 ng of S. parauberis, and 1 ng of S. iniae genomic DNA. Furthermore, this technique was found to have high specificity when tested with related bacterial species. This method represents a cheaper, faster, and reliable alternative for identifying major bacterial pathogens in olive flounder, the most important farmed fish in Korea.
Animals ; Edwardsiella tarda/genetics/*isolation & purification ; Enterobacteriaceae Infections/diagnosis/microbiology/*veterinary ; Fish Diseases/*diagnosis/microbiology ; Fisheries/*methods ; *Flatfishes ; Multiplex Polymerase Chain Reaction/economics/*veterinary ; Sensitivity and Specificity ; Streptococcal Infections/diagnosis/microbiology/*veterinary ; Streptococcus/genetics/*isolation & purification

The usage of essential oils as antimicrobial agents is gaining attention. Besides, pet turtles were known to harbor a range of pathogenic bacteria while the turtle keeping is a growing trend worldwide.The current study examined the antimicrobial activity of lemon grass oil (LGO) against seven species of Gram negative bacteria namely; Aeromonas hydrophila, A. caviae, Citrobacter freundii, Salmonella enterica, Edwardsiella tarda, Pseudomonas aeruginosa, and Proteus mirabilis isolated from three popular species of pet turtles. Along with the results of disc diffusion, minimum inhibitory and minimum bactericidal concentration (MIC and MBC) tests, LGO was detected as effective against 6 species of bacteria excluding P. aeruginosa. MIC of LGO for the strains except P. aeruginosa ranged from 0.016 to 0.5% (V/V). The lowest MIC recorded in the E. tarda strain followed by A. hydrophilla, C. freundii, P. mirabilis, and S. enterica. Interestingly, all the bacterial species except E. tarda were showing high multiple antimicrobial resistance (MAR) index values ranging from 0.36 to 0.91 upon the 11 antibiotics tested although they were sensitive to LGO.
Aeromonas hydrophila ; Animals ; Anti-Bacterial Agents ; Anti-Infective Agents ; Bacteria* ; Citrobacter freundii ; Cymbopogon* ; Diffusion ; Edwardsiella tarda ; Gram-Negative Bacteria ; Guinea Pigs ; Mirabilis ; Oils, Volatile ; Proteus mirabilis ; Pseudomonas aeruginosa ; Salmonella enterica ; Turtles*