Characteristics of an Enterococcus-like bacterium from Australia and South Africa, pathogenic for rainbow trout, Oncorhynchus mykiss (Walbaum) (original) (raw)
Foodborne Pathogens and Disease, 2015
The use of lactic acid bacteria of aquatic origin as probiotics constitutes an alternative strategy to the antibiotic treatment for disease control in aquaculture. Enterococci are currently used as probiotics in human and animal health. In this study, we evaluated the safety of 64 enterococci isolated from rainbow trout (Oncorhynchus mykiss, Walbaum), feed and rearing environment, and their antimicrobial activity against 9 fish pathogens. The 64 enterococcal isolates were identified to the species level by polymerase chain reaction (PCR), using specific primers for the different enterococcal species, and confirmed by superoxide dismutase gene sequencing. Enterococcus faecium and E. hirae were the most common species (42.2 and 35.9%, respectively). A total of 48 isolates (75%) showed phenotypic resistance to at least 1 antibiotic determined by a disk-diffusion method, and 25 isolates (39.1%) harbored at least 1 antibiotic resistance gene [erm(B), tet(M), tet(S), tet(K), tet(L), tet(T), vanC2, and aad(E)], detected by PCR. One (1.6%) isolate produced gelatinase and none produced hemolysin, using a plate assay. The virulence genes gelE (46.9%), efaAfs (17.2%), agg (1.6%), and hyl (1.6%) were detected by PCR. A total of 48 isolates (75%) exerted antimicrobial activity against 1 or more of the tested fish pathogens, using a stab-on-agar test. From these isolates, 21 (43.8%) harbored at least 1 bacteriocin-encoding gene (entP, entL50A and entL50B, hirJM79, entSE-K4, entQ and entA), detected by PCR. None of the enterococci showed bile deconjugation and mucin degradation abilities. A total of 17 enterococcal isolates (26.6%) that did not harbor any antibiotic resistance or virulence factor were considered safe for application as probiotics, including 6 isolates (35.3%) that showed antimicrobial activity against at least 1 fish pathogen and harbored at least 1 bacteriocin-encoding gene. Rainbow trout, feed, and rearing environment constitute an appropriate source for the isolation of enterococci as potential probiotic for aquaculture.
Enterococcus seriolicida sp. nov. a Fish Pathogen
1991
The properties and taxonomic position of bacterial strains isolated from diseased specimens of cultured yellowtail and eels were examined. The isolates were gram-positive, short-chain-forming, catalase-negative, facultatively anaerobic cocci. Growth at 10 and 45°C in 6.5% NaCl (pH 9.6) with 40% bile and in 0.1% methylene blue-milk were both positive. The isolates could be distinguished from other species of the genus Enterococcus by several biochemical characteristics and by Lancefield's group antigen. Guanine-plus-cytosine content of DNA was 44 mol% as determined by the thermal melting temperature. The value for DNA-DNA hybridization was sufficiently low to warrant distinguishing this species from reported Enterococcus species. The name Enterococcus seriolicida is proposed. The type strain is YT-3 (=ATCC 49156).
International Journal of Oceanography & Aquaculture
Background: The opportunistic fish pathogen are the main cause of mass mortality in several fish species and severe economic losses in different countries. This study was conducted to determine occurrence and characterization of Enterococcus faecalis from infected farmed African catfish in Ogun State, Nigeria. Methodology: The bacteria was isolated from infected farmed African catfish (Clarias gariepinus, n=128) with clinical signs of atrophied or reduced barbels, desquamation or abrasion of the skin, and ascites were purposively sampled in Ogun State. The isolates were identified based on morphological, biochemical tests, and 16S rRNA molecular characterization. The 16S rRNA gene sequence was analyzed using BLAST, submitted to the NCBI database, and an accession number was generated. Results: The percentage occurrence of Enterococcus faecalis isolates in infected Clarias gariepinus from Ogun State were; Ogun East 30.00% (18/60); Ogun Central 17.86% (5/28); Ogun West 12.50% (5/40). ...
Current Microbiology, 1996
The reference strains of Enterococcus seriolicida (ATCC 49156T) (T = type strain) and of Lactococcus garvieae (ATCC 43921T) and 30 field strains of Gram-positive cocci isolated from diseased rainbow trout in Italy were found to be phenotypically (API 20 STREPT and API 50 CH) and genetically (DNA-DNA hybridization) similar. The high DNA-DNA homologies (70–100%) and the low ΔTm(e) (less than 1.1°C) among these strains showed that Enterococcus seriolicida and Lactococcus garvieae are synonyms, describing a single bacterial species. E. seriolicida strains should be classified as L. garvieae, which must be considered as a major pathogen of freshwater and salt water fish with a world-wide distribution.
Science of The Total Environment, 2018
The role of European fish farms in the spread of antimicrobial-resistance in the environment and food chain, as well as possible sources of their contamination by clinically relevant antimicrobial-resistance bacteria is scarcely known. This study aimed to assess the contribution of Portuguese rural trout farms on dispersion of Enterococcus with antimicrobial-resistance and putative virulence genes in the environment and food chain, as well as to identify farms contamination sources. We also assessed the presence of Enterococcus with low-levels of antimicrobialresistance using epidemiological cutoffs (ECOFFs). Enterococcus spp. (n = 391) from water/sediment recovered upstream, within and downstream trout tanks, feed, trout (2 aquacultures; no antibiotic use) and marketed trout (8 supermarkets) showed variable resistance to tetracycline, erythromycin, ciprofloxacin, chloramphenicol, quinupristin-dalfopristin, nitrofurantoin or aminoglycosides. Antimicrobial-resistance rates were similar among upstream, within and downstream trout tank samples (P N 0.05), positioning water-supplying aquacultures as a source of multidrug-resistant (MDR) strains. Nevertheless, predominance of MDR E. faecium in feed, trout tanks and trout comparing to upstream samples, suggests feed as an additional aquaculture contamination source. The observation of E. faecium and E. faecalis susceptible to ampicillin and gentamicin by clinical breakpoints but with low-levels of resistance to those antimicrobials by ECOFFs breakpoints is of concern, as they might evolve throughout secondary genetic events to resistance levels with human clinical impact. Multiple
Diseases of Aquatic Organisms, 1997
A chronic condition of juvenile and adult rainbow trout was recorded in a trout farm over several years and resulted in significant mortality. The disease occurred mainly at low temperature. Necropsy findings were associated with hyperaemia and haemorrhage, in gills and viscera, with extensive cardiovascular lesions including myocarditis and epicarditis. Most of the losses were attributed to heart lesions and mortality peaked under stress conditions. A Gram-positive, chain-forming, coccoid to ovoid-shaped coccus identified as Vagococcus salmoninarum on the basis of phenotypic and genetic characteristics was regularly isolated from diseased fish. It was demonstrated to be the causative agent of the condition by infection experiments and histopathology, which also confirmed the affinity of the bacterium for the circulatory system. V. salmoninarum was resistant to inost of the antimicrobial drugs tested in vitro, and the treatments conducted in the field were ineffective. An attempt at vaccination did not provide encouraging results. V salmoninarum joins a list of Gram-positive bacteria responsible for chronic infections which do not respond to control procedures and which pose a serious threat to broodstock and large-sized fish. KEY WORDS: Vagococcus sal~noninarum . Rainbow trout . Gram-posit~ve bacteria . Natural infection .
Antibiotics, 2023
Fish has always been an integral part of Bengali cuisine and economy. Fish could also be a potential reservoir of pathogens. This study aimed to inquisite the distribution of virulence, biofilm formation, and antimicrobial resistance of Enterococcus faecalis isolated from wild and cultivated fish in Bangladesh. A total of 132 koi fish (Anabas scandens) and catfish (Heteropneustes fossilis) were collected from different markets in the Mymensingh district and analyzed to detect E. faecalis. E. faecalis was detected by conventional culture and polymerase chain reaction (PCR), followed by the detection of virulence genes by PCR. Antibiotic susceptibility was determined using the disk diffusion method, and biofilm-forming ability was investigated by crystal violet microtiter plate (CVMP) methods. A total of 47 wild and 40 cultured fish samples were confirmed positive for E. faecalis by PCR. The CVMP method revealed four per cent of isolates from cultured fish as strong biofilm formers, but no strong producers were found from the wild fish. In the PCR test, 45% of the isolates from the wild and cultivated fish samples were found to be positive for at least one biofilm-producing virulence gene, where agg, ace, gelE, pil, and fsrC genes were detected in 80, 95, 100, 93, and 100% of the isolates, respectively. Many of the isolates from both types of samples were multidrug resistant (MDR) (73% in local fish and 100% in cultured fish), with 100% resistance to erythromycin, linezolid, penicillin, and rifampicin in E. faecalis from cultured fish and 73.08, 69.23, 69.23, and 76.92%, respectively, in E. faecalis from wild fish. This study shows that E. faecalis from wild fish have a higher frequency of virulence genes and biofilm-forming genes than cultivated fish. However, compared to wild fish, cultured fish were found to carry E. faecalis that was more highly multidrug resistant. Present findings suggest that both wild and cultured fish could be potential sources for MDR E. faecalis, having potential public health implications.
Enterococcus alcedinis sp. nov., isolated from common kingfisher (Alcedo atthis)
INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2013
Two Gram-positive, catalase-negative bacterial strains were isolated from the cloaca of common kingfishers (Alcedo atthis). Repetitive sequence-based PCR fingerprinting using the (GTG) 5 primer grouped these isolates into a single cluster separated from all known enterococcal species. The two strains revealed identical 16S rRNA gene sequences placing them within the genus Enterococcus with Enterococcus aquimarinus LMG 16607 T as the closest relative (97.14 % similarity). Further taxonomic investigation using sequencing of the genes for the superoxide dismutase (sodA), phenylalanyl-tRNA synthase alpha subunit (pheS) and the RNA polymerase alpha subunit (rpoA) as well as application of whole-cell protein fingerprinting, automated ribotyping and extensive phenotyping confirmed that both strains belong to the same species. Based on data from this polyphasic study, these strains represent a novel species of the genus Enterococcus, for which the name Enterococcus alcedinis sp. nov. is proposed. The type strain is L34 T (5CCM 8433 T 5LMG 27164 T ).
Environmental Science & Technology, 2012
In this study, 212 Enterococcus isolates from 23 rainwater tank samples in Southeast Queensland (SEQ), Australia were identified to the species level. The isolates were also tested for the presence of 6 virulence genes associated with Enterococcus related infections. Among the 23 rainwater tank samples, 20 (90%), 10 (44%), 7 (30%), 5 (22%), 4 (17%), 2 (9%), and 1 (4%) samples yielded E. faecalis, E. mundtii, E. casselif lavus, E. faecium, E. hirae, E. avium, and E. durans, respectively. Among the 6 virulence genes tested, gelE and efaA were most prevalent, detected in 19 (83%) and 18 (78%) of 23 rainwater tank samples, respectively. Virulence gene ace was also detected in 14 (61%) rainwater tank samples followed by AS, esp (E. faecalis variant), and cylA genes which were detected in 3 (13%), 2 (9%), and 1 (4%) samples, respectively. In all, 120 (57%) Enterococcus isolates from 20 rainwater tank samples harbored virulence genes. Among these tank water samples, Enterococcus spp. from 5 (25%) samples harbored a single virulence gene and 15 (75%) samples were harboring two or more virulence genes. The significance of these strains in terms of health implications remains to be assessed. The potential sources of these strains need to be identified for the improved management of captured rainwater quality. Finally, it is recommended that Enterococcus spp. should be used as an additional fecal indicator bacterium in conjunction with E. coli for the microbiological assessment of rainwater tanks.
In this study, Enterococcus faecalis was isolated from100 samples of apparently healthy and diseased cultured Tilapia fish (Oreochromis niloticus) collected from 4 different fish farms at different localities in Kafr El-Sheikh governorate with an incidence of (20%) and it, also isolated from 12 samples (8 water samples and 4 ration samples) at the same infected farms with incidence of 50% from water samples, but the ration samples give a negative result for Enterococcus faecalis isolation. The antimicrobial susceptibility test has revealed that isolates were sensitive to vancomycin, amoxicillin, ampicillin, norfloxacin, gentamicin and ciprofloxacin, while resistant to cefotaxime, tetracycline, streptomycin and erythromycin. Molecular detection of some virulence genes from 8 Enterococcus faecalis isolates revealed that 3 isolates produced esp gene, 7 isolates produced asa1gene and all isolates produced EF3314 gene, while the cylA was not detected in any of Entero-coccus faecalis isolates. Also PCR results of some resistance genes showed that 8 isolates and 7 isolates were found to produce blaz and tetk genes respectively. Experimental infection test with some isolated Enterococcus faecalis revealed that the isolates caused mortality in fish with characteristic disease signs.