Displaying publications 21 - 40 of 44 in total

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  1. Fulltext Dissemination of streptococcal pyrogenic exotoxin G (spegg) with an IS-like element in fish isolates of Streptococcus dysgalactiae
    Abdelsalam M, Chen SC, Yoshida T
    FEMS Microbiol Lett, 2010 Aug 1;309(1):105-13.
    PMID: 20528946 DOI: 10.1111/j.1574-6968.2010.02024.x
    The Lancefield group C alpha-hemolytic Streptococcus dysgalactiae ssp. dysgalactiae (GCSD) causes systemic granulomatous inflammatory disease and high mortality rates in infected fish. Superantigen and streptolysin S genes are the most important virulence factors contributing to an invasive streptococcal infection. PCR amplification revealed that all strains isolated from moribund fish harbored the streptolysin S structural gene (sagA). GCSD fish isolates were PCR negative for emm, speA, speB, speC, speM, smeZ, and ssa. However, the size of the streptococcal pyrogenic exotoxin G (spegg) locus, a superantigen, in positive S. dysgalactiae fish and pig strains was variable. The ORF of the spegg locus of 26 GCSD fish strains and one GCSD pig strain was inserted with IS981SC. Interestingly, the ORF of the spegg locus of two fish strains of GCSD collected in Malaysia was inserted with an IS981SC-IS1161 hybrid IS element. The hybrid IS element was found in all of the GCSD fish isolates and one GCSD pig through PCR screening. Although no insertion sequence (IS) was detected in the spegg locus of S. dysgalactiae ssp. equisimilis (GCSE) strains, a five-nucleotide deletion mutation was detected in the ORF of the spegg locus of one GCSE strain at the supposed site of IS981SC insertion, resulting in a frameshift mutation.
    Matched MeSH terms: Fish Diseases/microbiology*
  2. Comparison of four antibiotics with indigenous marine Bacillus spp. in controlling pathogenic bacteria from shrimp and Artemia
    Banerjee S, Devaraja TN, Shariff M, Yusoff FM
    J Fish Dis, 2007 Jul;30(7):383-9.
    PMID: 17584435
    Use of antibiotics for the control of bacterial diseases in shrimp culture has caused several adverse impacts to the industry. This has resulted in the search for alternative environment friendly approaches to overcome bacterial infections. This study was conducted to investigate the use of beneficial bacteria as an alternative to antibiotics. Ten pathogenic bacterial species isolated from shrimp, Penaeus monodon, and Artemia cysts were tested for susceptibility to indigenous marine Bacillus subtilis AB65, Bacillus pumilus AB58, Bacillus licheniformis AB69 and compared with oxytetracycline, chloramphenicol, gentamicin and bacitracin, which are common antibiotics used in Asian aquaculture. The Bacillus spp. were isolated from the local marine environment for bioremediation use in shrimp hatcheries and were proven to reduce total ammonium nitrogen. The pathogenic bacterial isolates were 90% susceptible to B. subtilis AB65, 70% susceptible to B. pumilus AB58 and B. licheniformis AB69 and 100% susceptible to oxytetracycline, chloramphenicol and gentamicin but only 40% to bacitracin. Two representative isolates of the vibrio group, Vibrio alginolyticus VaM11 and Vibrio parahaemolyticus VpM1, when tested for competitive exclusion by a common broth method using the marine Bacillus spp., showed decreased viable counts from 10(8) to 10(2) cfu mL(-1). The results suggest that the action of the marine bacteria appears to be significant in protecting the host shrimp against pathogenic bacteria. In addition to the alternative use of antibiotics, the selected marine bacteria had additional bioremediation properties of reducing ammonia.
    Matched MeSH terms: Fish Diseases/microbiology
  3. Transmission of Streptococcus agalactiae from a hatchery into a newly established red hybrid tilapia, Oreochromis niloticus (L.) × Oreochromis mossambicus (Peters), farm
    Amal MN, Zamri-Saad M, Siti-Zahrah A, Zulkafli AR
    J Fish Dis, 2013 Aug;36(8):735-9.
    PMID: 23347250 DOI: 10.1111/jfd.12056
    Matched MeSH terms: Fish Diseases/microbiology
  4. Genome characterization of a novel vibriophage VpKK5 (Siphoviridae) specific to fish pathogenic strain of Vibrio parahaemolyticus
    Lal TM, Sano M, Ransangan J
    J Basic Microbiol, 2016 Aug;56(8):872-88.
    PMID: 26960780 DOI: 10.1002/jobm.201500611
    Vibrio parahaemolyticus has long been known pathogenic to shrimp but only recently it is also reported pathogenic to tropical cultured marine finfish. Traditionally, bacterial diseases in aquaculture are often treated using synthetic antibiotics but concern due to side effects of these chemicals is elevating hence, new control strategies which are both environmental and consumer friendly, are urgently needed. One promising control strategy is the bacteriophage therapy. In this study, we report the isolation and characterization of a novel vibriophage (VpKK5), belonging to the family Siphoviridae that was specific and capable of complete lysing the fish pathogenic strain of V. parahaemolyticus. The VpKK5 exhibited short eclipse and latent periods of 24 and 36 min, respectively, but with a large burst size of 180 pfu/cell. The genome analysis revealed that the VpKK5 is a novel bacteriophage with the estimated genome size of 56,637 bp and has 53.1% G + C content. The vibriophage has about 80 predicted open reading frames consisted of 37 complete coding sequences which did not match to any protein databases. The analysis also found no lysogeny and virulence genes in the genome of VpKK5. With such genome features, we suspected the vibriophage is novel and could be explored for phage therapy against fish pathogenic strains of V. parahaemolyticus in the near future.
    Matched MeSH terms: Fish Diseases/microbiology*
  5. The effect of feed-based vaccination on tilapia farm endemic for streptococcosis
    Ismail MS, Syafiq MR, Siti-Zahrah A, Fahmi S, Shahidan H, Hanan Y, et al.
    Fish Shellfish Immunol, 2017 Jan;60:21-24.
    PMID: 27864157 DOI: 10.1016/j.fsi.2016.11.040
    A tilapia farm experiencing endemic streptococcosis was selected to study the effect of vaccination with a feed-based vaccine on naturally ocurring streptococcosis. A total of 9000 red tilapia, Oreochromis niloticus × Oreochromis mossambicus of 100 ± 20 g were divided into 9 cages. Fish of Group 1 in cages 1, 2 and 3 were not vaccinated. Group 2 in cages 4, 5 and 6 were vaccinated on days 0 and 14 (single booster) while Group 3 in cages 7, 8 and 9 were vaccinated on days 0, 14 and 42 (double booster). Vaccination was done by oral administration of the feed-based bacterin vaccine at 4% bodyweight. Samples of serum for antibody study and the brain, eyes and kidney for bacterial isolation were collected at 14-day intervals. The study was carried out during the critical months between April and June. Following vaccination and booster, there was significant (p fish. In week 4, the isolation rate was 13 ± 5.7% but increased to 18 ± 7.6% in week 8, to 25 ± 10.0% in week 10, to 28 ± 5.8% in week 12 and 25 ± 7.3% in week 14. The average isolation rate was 28 ± 7.2%, 18 ± 7.1% and 13 ± 8.2% of the fish sampled from unvaccinated, single booster and double booster groups, respectively. At the end of the study period, the survival rate was 45.2 ± 2.45% for unvaccinated, 65.3 ± 4.8% for single booster and 75.1 ± 2.1% for double booster groups. Vaccinating fish in endemic farm might not eliminate the disease but was able to significantly improve the survival rate.
    Matched MeSH terms: Fish Diseases/microbiology
  6. Comparative evaluation of dietary probiotics Bacillus subtilis WB60 and Lactobacillus plantarum KCTC3928 on the growth performance, immunological parameters, gut morphology and disease resistance in Japanese eel, Anguilla japonica
    Lee S, Katya K, Park Y, Won S, Seong M, Hamidoghli A, et al.
    Fish Shellfish Immunol, 2017 Feb;61:201-210.
    PMID: 28034835 DOI: 10.1016/j.fsi.2016.12.035
    The current experiment was conducted to evaluate and compare the efficacy of two different probiotics Bacillus subtilis WB60 and Lactobacillus plantarum KCTC3928 in diet of Japanese eel, Anguilla japonica. Seven experimental diets were formulated to contain no probiotics (CON), three graded levels of B. subtilis at 106 (BS1), 107 (BS2), 108 (BS3) and L. plantarum at 106 (LP1), 107 (LP2), 108 (LP3) CFU/g diet. Twenty fish averaging 8.29 ± 0.06 g were distributed in to 21 aquaria and were randomly assigned to one of the experimental diets in triplicate groups. Average weight gain (WG), feed efficiency (FE), and protein efficiency ratio (PER) of fish fed B. subtilis at 107 (BS2) and 108 (BS3) CFU/g diet were significantly higher than those of fish fed other experimental diets (P fish fed B. subtilis at 107 (BS2) and 108 (BS3) CFU/g diet were detected to be significantly higher than that from fish fed CON diet (P fish fed B. subtilis at 107 and 108 CFU/g diet were recorded to be significantly higher than those of fish fed other experimental diets (P fish fed108 (BS3) CFU/g diet as compared to other treatment groups. Whereas, results from the disease challenge test with bacteria Vibrio angulillarum showed significantly lower survival rate for fish fed CON diet than those of fish fed other experimental diets. Therefore, these results indicated that oral supplement of B. subtilis at 108 (BS3) CFU/g diet could be a more effective source of probiotic compared to L. plantarum in Japanese eel.
    Matched MeSH terms: Fish Diseases/microbiology
  7. Study on Streptococcus agalactiae infection in Javanese medaka (Oryzias javanicus Bleeker, 1854) model
    Amal MNA, Ismail A, Saad MZ, Md Yasin IS, Nasruddin NS, Mastor SS, et al.
    Microb Pathog, 2019 Jun;131:47-52.
    PMID: 30940607 DOI: 10.1016/j.micpath.2019.03.034
    This study determines the median lethal dose, and describes the clinico-pathological changes and disease development following Streptococcus agalactiae infection in Javanese medaka model. Javanese medakas were infected with S. agalactiae via intraperitoneal (IP) from 104 to 108 CFU/mL, and immersion (IM) route from 103 to 107 CFU/mL. The LD50-240h and clinico-pathological changes of the fish was determined until 240 h post infection (hpi). Next, the disease development was determined for 96 hpi in the fish following IP and IM infection at 103 CFU/mL and 104 CFU/mL, respectively. The LD50-240h of S. agalactiae in Javanese medaka was lower following IP injection (4.5 × 102 CFU/mL), compared to IM route (3.5 × 103 CFU/mL). The clinical signs included separating from the schooling group, swimming at the surface of water column, lethargy, erratic swimming pattern, corneal opacity and exophthalmia. Histopathological examinations revealed generalized congestion in almost all internal organs, particularly in liver and brain, while the kidney displayed tubular necrosis. Both IP and IM routes showed significant positive correlation (p fish tissue and fish deaths. Moreover, the lesions for histopathological scoring in selected organs following IP and IM challenges were also reflecting the CFU/g and fish deaths. This study indicates the capability of Javanese medaka as a model organism in study of streptococcosis development.
    Matched MeSH terms: Fish Diseases/microbiology*
  8. Recombinant ferritin-H induces immunosuppression in European sea bass larvae (Dicentrarchus labrax) rather than immunostimulation and protection against a Vibrio anguillarum infection
    Yaacob EN, De Geest BG, Goethals J, Bajek A, Dierckens K, Bossier P, et al.
    Vet Immunol Immunopathol, 2018 Oct;204:19-27.
    PMID: 30596377 DOI: 10.1016/j.vetimm.2018.09.001
    Vibrio anguillarum causes high mortality in European sea bass (Dicentrarchus labrax) larviculture. In this study, we evaluated if the recombinant sea bass ferritin-H could stimulate the innate immune system of gnotobiotic European sea bass larvae resulting in protection against a V. anguillarum challenge. We also evaluated the effect of a V. anguillarum infection on the transcription of immune-related genes in gnotobiotic European sea bass larvae. Recombinant sea bass ferritin-H was produced, encapsulated in calcium alginate microparticles and orally delivered to sea bass larvae at seven days after hatching. Our results showed V. anguillarum caused an acute infection, resulting in high mortality. The infection significantly upregulated the expression of tlr3, tlr5, cas1, il1β, tnfα, mif, il10, cc1, cxcl8 at 18, 24 and 36 h post infection, but not of the chemokine receptor genes cxcr4 and ccr9. There was no protective effect of ferritin-H. Remarkably, ferritin-H caused significantly higher transcript levels for cxcr4 and ccr9. Sea bass ferritin-H was more likely involved in immune-suppression and results point in the direction of a negative regulation of CXCR4 resulting in inhibition of cell proliferation, differentiation and migration which is detrimental to innate immunity and might explain the non-protective effect of ferritin-H in fish larvae.
    Matched MeSH terms: Fish Diseases/microbiology*
  9. Phenotypic and genotypic characteristics of Mycobacterium isolates from fighting fish Betta spp. in Malaysia
    Najiah M, Lee KL, Noorasikin H, Nadirah M, Lee SW
    Res Vet Sci, 2011 Dec;91(3):342-5.
    PMID: 20971487 DOI: 10.1016/j.rvsc.2010.09.010
    Mycobacteriosis due to mycobacteria is one of the most common bacterial diseases in ornamental fish. We describe here the phenotypic and genotypic characteristics of Mycobacterium isolates from fighting fish Betta spp. using ATCC Mycobacterium marinum, Mycobacterium fortuitum and Mycobacterium chelonae as references. A total of four isolates (M1, M2, M3, M4) were obtained from four out of 106 fish samples using selective agar, and identified to Mycobacterium genus using acid-fast staining and 16s rRNA gene-based genus specific polymerase chain reaction. DNA sequencing and NCBI-BLAST analysis further identified isolate M1 as M. marinum and isolates M2, M3, M4 as M. fortuitum. Morphological, physiological and biochemical tests were carried out for phenotypic characterizations. Universal M13 and wild-type phage M13 RAPD dendogram was generated to illustrate the genetic relationship of the isolates and reference strains.
    Matched MeSH terms: Fish Diseases/microbiology*
  10. The effects of fish gender on susceptibility to acute Streptococcus agalactiae infection in Javanese medaka Oryzias javanicus
    Amal MNA, Zarif ST, Suhaiba MS, Aidil MRM, Shaqinah NN, Zamri-Saad M, et al.
    Microb Pathog, 2018 01;114:251-254.
    PMID: 29217326 DOI: 10.1016/j.micpath.2017.11.069
    This study describes the susceptibility of different fish gender following acute Streptococcus agalactiae infection by using Javanese medaka Oryzias javanicus as test fish. The fish were grouped into four groups, which were: (1) all-male; (2) all-female; (3) mixed-gender (1 male: 1 female ratio); and (4) control non-infected (1 male: 1 female ratio). The fish in group 1, 2 and 3 were intraperitoneally exposed to 5.4 × 108 CFU/mL of S. agalactiae, while for group 4, the fish were exposed using sterile broth. The main clinical signs and histopathological changes of infected Javanese medaka were commonly observed in S. agalactiae infected fishes. However, no difference on clinical signs and histopathological changes of fish in group 1, 2 and 3 were noticed. The Javanese medaka mortality in group 1, 2 and 3 were observed from 4 h post infection (hpi) to 6 hpi, with the cumulative mortality from 3% to 30%. Then, the mortality increased at 12 hpi, with the range from 53% to 80%. However, 100% of the infected fish dead at 24 hpi. No clinical sign, histopathological change and fish mortality recorded in group 4. Generally, the clinical signs, mortality patterns, cumulative mortality and histopathological changes of Javanese medaka infected by S. agalactiae did not show any difference between the all-male, all-female and mixed-gender groups. This indicates that the susceptibility of fish to S. agalactiae infection is not influenced by their gender.
    Matched MeSH terms: Fish Diseases/microbiology*
  11. Streptococcus agalactiae isolates from cultured fishes in Malaysia manifesting low resistance pattern towards selected antibiotics
    Aisyhah MA, Amal MN, Zamri-Saad M, Siti-Zahrah A, Shaqinah NN
    J Fish Dis, 2015 Dec;38(12):1093-8.
    PMID: 25704397 DOI: 10.1111/jfd.12351
    Matched MeSH terms: Fish Diseases/microbiology
  12. Fulltext Molecular characterization of a novel proto-type antimicrobial protein galectin-1 from striped murrel
    Arasu A, Kumaresan V, Sathyamoorthi A, Chaurasia MK, Bhatt P, Gnanam AJ, et al.
    Microbiol Res, 2014 Nov;169(11):824-34.
    PMID: 24780642 DOI: 10.1016/j.micres.2014.03.005
    In this study, we reported a molecular characterization of a novel proto-type galectin-1 from the striped murrel Channa striatus (named as CsGal-1). The full length CsGal-1 was identified from an established striped murrel cDNA library and further we confirmed the sequence by cloning. The complete cDNA sequence of CsGal-1 is 590 base pairs (bp) in length and its coding region encoded a poly peptide of 135 amino acids. The polypeptide contains a galactoside binding lectin domain at 4-135. The domain carries a sugar binding site at 45-74 along with its signatures (H(45)-X-Asn(47)-X-Arg(49) and Trp(69)-X-X-Glu(72)-X-Arg(74)). CsGal-1 shares a highly conserved carbohydrate recognition domain (CRD) with galectin-1 from other proto-type galectin of teleosts. The mRNA expressions of CsGal-1 in healthy and various immune stimulants including Aphanomyces invadans, Aeromonas hydrophila, Escherchia coli lipopolysaccharide and poly I:C injected tissues of C. striatus were examined using qRT-PCR. CsGal-1 mRNA is highly expressed in kidney and is up-regulated with different immune stimulants at various time points. To understand its biological activity, the coding region of CsGal-1 gene was expressed in an E. coli BL21 (DE3) cloning system and its recombinant protein was purified. The recombinant CsGal-1 protein was agglutinated with mouse erythrocytes at a concentration of 4μg/mL in a calcium independent manner. CsGal-1 activity was inhibited by d-galactose at 25mM(-1) and d-glucose and d-fructose at 100mM(-1). The results of microbial binding assay showed that the recombinant CsGal-1 protein agglutinated only with the Gram-negative bacteria. Interestingly, we observed no agglutination against Gram-positive bacteria. Overall, the study showed that CsGal-1 is an important immune gene involved in the recognition and elimination of pathogens in C. striatus.
    Matched MeSH terms: Fish Diseases/microbiology
  13. Development and efficacy of feed-based recombinant vaccine encoding the cell wall surface anchor family protein of Streptococcus agalactiae against streptococcosis in Oreochromis sp
    Nur-Nazifah M, Sabri MY, Siti-Zahrah A
    Fish Shellfish Immunol, 2014 Mar;37(1):193-200.
    PMID: 24486904 DOI: 10.1016/j.fsi.2014.01.011
    This study was carried out to determine the antibody responses and protective capacity of an inactivated recombinant vaccine expressing the cell wall surface anchor family protein of Streptococcus agalactiae following oral vaccination against streptococcosis in tilapia. Tilapia were vaccinated orally with 10(6) CFU/mL of the recombinant vaccine incorporated in feed (feed-based recombinant vaccine) (vaccinated group or Group 1), 10(6) CFU/mL of pET-32 Ek/LIC vector without cell wall surface anchor family protein (control group or Group 2), 10(6) CFU/mL of formalin-killed cells of S. agalactiae vaccine incorporated in feed was also prepared (feed-based vaccine) (vaccinated group or Group 3), and unvaccinated control group or Group 4 (fed with commercial pellets). During the course of study, serum, mucus and gut lavage fluid were collected to evaluate the antibody levels via enzyme-linked immunosorbent assay (ELISA). The results showed that tilapia immunized with the feed-based recombinant vaccine developed a strong and significantly (P 
    Matched MeSH terms: Fish Diseases/microbiology*
  14. Fulltext Unusual long-chain N-acyl homoserine lactone production by and presence of quorum quenching activity in bacterial isolates from diseased tilapia fish
    Chang CY, Koh CL, Sam CK, Chan XY, Yin WF, Chan KG
    PLoS One, 2012;7(8):e44034.
    PMID: 22952864 DOI: 10.1371/journal.pone.0044034
    Growth-dependent cell-cell communication termed quorum sensing is a key regulatory system in bacteria for controlling gene expression including virulence factors. In this study five potential bacterial pathogens including Bacillus sp. W2.2, Klebsiella sp. W4.2, Pseudomonas sp. W3 and W3.1 and Serratia sp. W2.3 were isolated from diseased Tilapia fish in Malaysia, supplied by the leading global fish supplier. Proteolytic activity assays confirmed that with the exception of Klebsiella sp. W4.2, all isolates showed distinct proteolytic activity. Furthermore Bacillus sp. W2.2 and Pseudomonas sp. strains W3 and W3.1 also displayed haemolytic activity. By using high resolution liquid chromatography mass spectrometry, we revealed the presence of unusually long-chain N-(3-oxohexadecanoyl)-homoserine lactone (3-oxo-C16-HSL) from Pseudomonas sp. W3.1 and N-dodecanoyl-homoserine lactone (C12-HSL) from Serratia sp. W2.3, respectively. Interestingly, Pseudomonas sp. W3.1 also produced a wide range of Pseudomonas quinolone signalling (PQS) molecules. Pseudomonas sp. W3 did not show any quorum sensing properties but possessed quorum quenching activity that inactivated AHLs. This study is the first documentation that shows unusual long-chain AHLs production in Serratia sp. and Pseudomonas sp. isolated from diseased fish and the latter also produce a wide range of PQS molecules.
    Matched MeSH terms: Fish Diseases/microbiology*
  15. Fulltext Phenotypic and genetic characterizations of Streptococcus dysgalactiae strains isolated from fish collected in Japan and other Asian countries
    Abdelsalam M, Chen SC, Yoshida T
    FEMS Microbiol Lett, 2010 Jan;302(1):32-8.
    PMID: 19895643 DOI: 10.1111/j.1574-6968.2009.01828.x
    Lancefield group C Streptococcus dysgalactiae is an emerging fish pathogen, which was first isolated in 2002 in Japan. Streptococcus dysgalactiae isolates collected from diseased fish in Japan (n=12), Taiwan (n=12), China (n=2), Malaysia (n=3), and Indonesia (n=1) were characterized using biased sinusoidal field gel electrophoresis (BSFGE), sodA gene sequence analysis, and antimicrobial susceptibility. These isolates exhibited high phenotypic homogeneity irrespective of the countries from where the strains were collected. Seventeen isolates were found to be resistant to oxytetracycline and carried the tet(M) gene, except for the strains collected in Taiwan and the PP1564 strain collected in China. The sodA gene sequence analysis revealed that 23 isolates were identical, except for one Japanese isolate (KNH07902), in which a single nucleotide differed from that of the other isolates. Based on BSFGE typing by ApaI macrorestriction, the isolates - including the Japanese, Taiwanese, and Chinese isolates - could be grouped into one main cluster at a 70% similarity level. However, the macrorestriction genotypes of some isolates were apparently distinct from those of the main cluster.
    Matched MeSH terms: Fish Diseases/microbiology*
  16. Fulltext Nucleospora cyclopteri n. sp., an intranuclear microsporidian infecting wild lumpfish, Cyclopterus lumpus L., in Icelandic waters
    Freeman MA, Kasper JM, Kristmundsson Á
    Parasit Vectors, 2013;6:49.
    PMID: 23445616 DOI: 10.1186/1756-3305-6-49
    Commercial fisheries of lumpfish Cyclopterus lumpus have been carried out in Iceland for centuries. Traditionally the most valuable part is the eggs which are harvested for use as a caviar substitute.Previously reported parasitic infections from lumpfish include an undescribed intranuclear microsporidian associated with abnormal kidneys and mortalities in captive lumpfish in Canada. During Icelandic lumpfish fisheries in spring 2011, extensive enlargements to the kidneys were observed in some fish during processing. The aim of this study was to identify the pathogen responsible for these abnormalities.
    Matched MeSH terms: Fish Diseases/microbiology*
  17. Expression of the serum opacity factor gene and the variation in its upstream region in Streptococcus dysgalactiae isolates from fish
    Nishiki I, Minami T, Chen SC, Itami T, Yoshida T
    J Gen Appl Microbiol, 2012;58(6):457-63.
    PMID: 23337581
    Group C Streptococcus dysgalactiae (GCSD) is a pathogen of farmed fish. Almost all GCSD isolates from Asian countries, including Japan, Taiwan, Malaysia, and China, have a serum opacity factor (SOF-FD). Although the SOF-FD sequences in different GCSD isolates are identical, different opacification activities are observed. Three types of variations were observed in the upstream sequence of the sof-FD gene in GCSD isolates with different SOF-FD activities. Type 1 was characterized by insertion of an IS981-like element into the upstream region of the sof-FD gene. In Type 2, an IS981-like element was inserted into the upstream region in a direction opposite to that in Type 1. In Type 3, no IS element was inserted. Type 1 was predominant among Japanese isolates (129 of 133). Isolates from other Asian countries were generally Type 3 (13 of 16). Except for 1 strain, Type 1 strains exhibited opacification activities with optical densities (ODs)>0.6, while Type 2 and Type 3 strains have low opacification activities (ODs >0.2). Only Type 1 strains have putative -10 and -35 promoter regions upstream of the sof-FD gene, and the expression level of the sof-FD gene was higher in Type 1 strains than in Type 2 and Type 3 strains.
    Matched MeSH terms: Fish Diseases/microbiology*
  18. Fulltext One hypervirulent clone, sequence type 283, accounts for a large proportion of invasive Streptococcus agalactiae isolated from humans and diseased tilapia in Southeast Asia
    Barkham T, Zadoks RN, Azmai MNA, Baker S, Bich VTN, Chalker V, et al.
    PLoS Negl Trop Dis, 2019 06;13(6):e0007421.
    PMID: 31246981 DOI: 10.1371/journal.pntd.0007421
    BACKGROUND: In 2015, Singapore had the first and only reported foodborne outbreak of invasive disease caused by the group B Streptococcus (GBS; Streptococcus agalactiae). Disease, predominantly septic arthritis and meningitis, was associated with sequence type (ST)283, acquired from eating raw farmed freshwater fish. Although GBS sepsis is well-described in neonates and older adults with co-morbidities, this outbreak affected non-pregnant and younger adults with fewer co-morbidities, suggesting greater virulence. Before 2015 ST283 had only been reported from twenty humans in Hong Kong and two in France, and from one fish in Thailand. We hypothesised that ST283 was causing region-wide infection in Southeast Asia.

    METHODOLOGY/PRINCIPAL FINDINGS: We performed a literature review, whole genome sequencing on 145 GBS isolates collected from six Southeast Asian countries, and phylogenetic analysis on 7,468 GBS sequences including 227 variants of ST283 from humans and animals. Although almost absent outside Asia, ST283 was found in all invasive Asian collections analysed, from 1995 to 2017. It accounted for 29/38 (76%) human isolates in Lao PDR, 102/139 (73%) in Thailand, 4/13 (31%) in Vietnam, and 167/739 (23%) in Singapore. ST283 and its variants were found in 62/62 (100%) tilapia from 14 outbreak sites in Malaysia and Vietnam, in seven fish species in Singapore markets, and a diseased frog in China.

    CONCLUSIONS: GBS ST283 is widespread in Southeast Asia, where it accounts for a large proportion of bacteraemic GBS, and causes disease and economic loss in aquaculture. If human ST283 is fishborne, as in the Singapore outbreak, then GBS sepsis in Thailand and Lao PDR is predominantly a foodborne disease. However, whether transmission is from aquaculture to humans, or vice versa, or involves an unidentified reservoir remains unknown. Creation of cross-border collaborations in human and animal health are needed to complete the epidemiological picture.

    Matched MeSH terms: Fish Diseases/microbiology*
  19. Biofilm is associated with chronic streptococcal meningoencephalitis in fish
    Isiaku AI, Sabri MY, Ina-Salwany MY, Hassan MD, Tanko PN, Bello MB
    Microb Pathog, 2017 Jan;102:59-68.
    PMID: 27890651 DOI: 10.1016/j.micpath.2016.10.029
    Biofilms are aggregates of attached microbial organisms whose existence on tissues is often recognised as a mechanism for the establishment of most chronic diseases. Herein we investigated the ability of piscine Streptococcus agalactiae, an important aquatic pathogen, for adaptation to this sessile lifestyle in vitro and in the brain of a tilapia fish model. Piscine S. agalactiae exhibited a weak attachment to polystyrene plates and expressed a low biofilm phenotype under the study conditions. Furthermore, fluorescent in situ hybridization and confocal laser scanning microscopy revealed discrete aggregates of attached S. agalactiae within brain tissues and around meningeal surfaces. They were embedded in an exopolysaccharide containing matrix, intractable to inflammatory response and showed some level of resistance to penicillin despite proven susceptibility on sensitivity test. Intracellular bacterial aggregates were also observed, moreover, antibody mediated response was not demonstrated during infection. Nucleated erythrocytes appear to facilitate brain invasion possibly via the Trojan horse mechanism leading to a granulomatous inflammation. We have demonstrated that biofilm is associated with persistence of S. agalactiae and the development of chronic meningoencephalitis in fish.
    Matched MeSH terms: Fish Diseases/microbiology*
  20. Current knowledge of metabolomic approach in infectious fish disease studies
    Low CF, Rozaini MZH, Musa N, Syarul Nataqain B
    J Fish Dis, 2017 Oct;40(10):1267-1277.
    PMID: 28252175 DOI: 10.1111/jfd.12610
    The approaches of transcriptomic and proteomic have been widely used to study host-pathogen interactions in fish diseases, and this is comparable to the recently emerging application of metabolomic in elucidating disease-resistant mechanisms in fish that gives new insight into potential therapeutic strategies to improve fish health. Metabolomic is defined as the large-scale study of all metabolites within an organism and represents the frontline in the 'omics' approaches, providing direct information on the metabolic responses and perturbations in metabolic pathways. In this review, the current research in infectious fish diseases using metabolomic approach will be summarized. The metabolomic approach in economically important fish infected with viruses, bacteria and nematodes will also be discussed. The potential of the metabolomic approach for management of these infectious diseases as well as the challenges and the limitations of metabolomic in fish disease studies will be explored. Current review highlights the impacts of metabolomic studies in infectious fish diseases, which proposed the potential of new therapeutic strategies to enhance disease resistance in fish.
    Matched MeSH terms: Fish Diseases/microbiology
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