Pathogens

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13 pages, 836 KiB

Open AccessArticle

Occurrence and Antimicrobial Susceptibility Profiles of Multidrug-Resistant Aeromonads Isolated from Freshwater Ornamental Fish in Chiang Mai Province

by Banthita Saengsitthisak, Wasana Chaisri, Veerasak Punyapornwithaya, Raktham Mektrirat, Srikanjana Klayraung, John K. Bernard and Surachai Pikulkaew

Pathogens 2020, 9(11), 973; https://doi.org/10.3390/pathogens9110973 - 22 Nov 2020

Cited by 26 | Viewed by 3465

Abstract

Antimicrobials are commonly used to prevent and treat disease in the ornamental fish industry. However, the indiscriminate and comprehensive overuse of unregulated antimicrobials without appropriate diagnostic examination could contribute to the development of antimicrobial-resistant strains of bacterial pathogens. Moreover, human infections caused by [...] Read more.

Antimicrobials are commonly used to prevent and treat disease in the ornamental fish industry. However, the indiscriminate and comprehensive overuse of unregulated antimicrobials without appropriate diagnostic examination could contribute to the development of antimicrobial-resistant strains of bacterial pathogens. Moreover, human infections caused by pathogens transmitted from fish or the aquatic environment are quite common. The frequent detection of antimicrobial resistance in ornamental fish and their environments are inevitable so as to decrease the transfer of antimicrobial-resistant bacteria from aquatic sources to other environments. This study evaluated the prevalence of common bacteria species and the antimicrobial susceptibility profile in ornamental fish that were sold in an ornamental fish shop in Chiang Mai, Thailand. Aeromonas spp. were the most dominant of the isolated species from the ornamental fish samples and accounted for 68.09% of the total. Other species detected included Vibrio spp., Pseudomonas spp., and Citrobacter spp. A high percentage of resistance to amoxicillin (93.75%), oxytetracycline (79.69%), and erythromycin (75.00%) was observed among the Aeromonas spp. The antimicrobial resistance information for ornamental fish is very limited, and the results from this study indicate that the Aeromonas spp. are highly resistant to several important antibiotics. The results suggest that additional steps should be taken to educate store owners to reduce the indiscriminate use of these antibiotics to decrease the antimicrobial resistance in ornamental fish to potentially improve public health. Full article

(This article belongs to the Special Issue Emerging Infectious Diseases in Aquaculture)

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11 pages, 11945 KiB

Open AccessEditor’s ChoiceArticle

Mycobacterium pseudoshottsii in Mediterranean Fish Farms: New Trouble for European Aquaculture?

by Davide Mugetti, Katia Varello, Andrea Gustinelli, Paolo Pastorino, Vasco Menconi, Daniela Florio, Maria Letizia Fioravanti, Elena Bozzetta, Simona Zoppi, Alessandro Dondo and Marino Prearo

Pathogens 2020, 9(8), 610; https://doi.org/10.3390/pathogens9080610 - 27 Jul 2020

Cited by 17 | Viewed by 4222

Abstract

Mycobacterium pseudoshottsii, a slow-growing mycobacterium closely related to M. marinum, has been isolated only in wild fish in the United States and in Japanese fish farms to date. Here, we report cases of mortality in three farmed fish species (Dicentrarchus [...] Read more.

Mycobacterium pseudoshottsii, a slow-growing mycobacterium closely related to M. marinum, has been isolated only in wild fish in the United States and in Japanese fish farms to date. Here, we report cases of mortality in three farmed fish species (Dicentrarchus labrax, Sparus aurata, and Sciaenops ocellatus) caused by M. pseudoshottsii in Italy. Samples underwent necropsy, histology, and culture with pathogen identification based on PCR and sequencing of housekeeping genes (16S rRNA, hsp65, rpoB). Multifocal to coalescing granulomatous and necrotizing inflammation with acid-fast bacilli were observed in the parenchymatous organs, from which M. pseudoshottsii was isolated and identified. Phylogenetic analysis confirmed the results of gene sequencing and allowed subdivision of the isolates into three distinct groups. M. pseudoshottsii poses a potential threat for Mediterranean aquaculture. Its origin in the area under study needs to be clarified, as well as the threat to the farmed fish species. Full article

(This article belongs to the Special Issue Emerging Infectious Diseases in Aquaculture)

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18 pages, 1877 KiB

Open AccessEditor’s ChoiceArticle

Prevalence of Infectious Spleen and Kidney Necrosis Virus (ISKNV), Nervous Necrosis Virus (NNV) and Ectoparasites in Juvenile Epinephelus spp. Farmed in Aceh, Indonesia

by Bakhtiar Sah Putra, Paul M. Hick, Evelyn Hall, Richard J. Whittington, Razi Khairul, Evarianti, Nurbariah and Joy A. Becker

Pathogens 2020, 9(7), 578; https://doi.org/10.3390/pathogens9070578 - 16 Jul 2020

Cited by 11 | Viewed by 4443

Abstract

A cross-sectional survey was used to estimate the prevalence of infections with the Infectious spleen and kidney necrosis virus (ISKNV, Megalocytivirus), nervous necrosis virus (NNV, Betanodavirus), and infestations with ectoparasites during the rainy season in juvenile grouper (Epinephelus spp.) farmed [...] Read more.

A cross-sectional survey was used to estimate the prevalence of infections with the Infectious spleen and kidney necrosis virus (ISKNV, Megalocytivirus), nervous necrosis virus (NNV, Betanodavirus), and infestations with ectoparasites during the rainy season in juvenile grouper (Epinephelus spp.) farmed in Aceh, Indonesia. The survey was intended to detect aquatic pathogens present at 10% prevalence with 95% confidence, assuming 100% sensitivity and specificity using a sample size of 30 for each diagnostic test. Eight populations of grouper from seven farms were sampled. Additional targeted sampling was conducted for populations experiencing high mortality. Infection with NNV was detected at all farms with seven of the eight populations being positive. The apparent prevalence for NNV ranged from 0% (95% CI: 0–12) to 73% (95% CI: 54–88). All of the fish tested from the targeted samples (Populations 9 and 10) were positive for NNV and all had vacuolation of the brain and retina consistent with viral nervous necrosis (VNN). Coinfections with ISKNV were detected in five populations, with the highest apparent prevalence being 13% (95% CI: 4–31%). Trichodina sp., Cryptocaryon irritans and Gyrodactylus sp. were detected at three farms, with 66% to 100% of fish being infested. Hybrid grouper sourced from a hatchery were 5.4 and 24.9 times more likely to have a NNV infection and a higher parasite load compared to orange-spotted grouper collected from the wild (p < 0.001). This study found that VNN remains a high-impact disease in grouper nurseries in Aceh, Indonesia. Full article

(This article belongs to the Special Issue Emerging Infectious Diseases in Aquaculture)

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15 pages, 8034 KiB

Open AccessArticle

First Isolation and Characterization of Chryseobacterium cucumeris SKNUCL01, Isolated from Diseased Pond loach (Misgurnus anguillicaudatus) in Korea

by Sang Guen Kim, Sib Sankar Giri, Sang Wha Kim, Jun Kwon, Sung Bin Lee and Se Chang Park

Pathogens 2020, 9(5), 397; https://doi.org/10.3390/pathogens9050397 - 21 May 2020

Cited by 6 | Viewed by 3883

Abstract

Loaches are widely distributed throughout the natural environment and are consumed for medicinal purposes in East Asia. Usually, loaches are cultured in ponds where the water conditions can easily cause bacterial infections. Infections due to bacterial pathogens such as Aeromonas have been well [...] Read more.

Loaches are widely distributed throughout the natural environment and are consumed for medicinal purposes in East Asia. Usually, loaches are cultured in ponds where the water conditions can easily cause bacterial infections. Infections due to bacterial pathogens such as Aeromonas have been well described in cultured loaches; however, there is no report regarding Chryseobacterium infection. This study focused on the elucidation of the pathogenic and antibiotic resistance characteristics of C. cucumeris, SKNUCL01, isolated from diseased loaches (Misgurnus anguillicaudatus). SKNUCL01 forms a biofilm, which is associated with its virulence. Koch’s postulates were satisfied with a lethal dose 50 (LD₅₀) of 8.52 × 10⁷ colony-forming units (CFU)/ml. Abrasion facilitates the mortality of the fish, which makes it a possible infection route for C. cucumeris. The strain showed resistance to nearly all tested antibiotics, such as trimethoprim/sulfamethoxazole, levofloxacin, and ciprofloxacin, formerly considered effective treatments. Phenotypic analyses for antibiotic resistance—the combined disk test, double-disk synergy test, modified Hodge test, and efflux pump inhibition test—revealed that the resistance of SKNUCL01 originated from metallo-beta lactamases (MBLs) and efflux pumps. Our findings provide evidence that could result in a breakthrough against multidrug-resistant Chryseobacterium infection in the aquaculture industry; the antibiotic resistance-related genes can be elucidated through future study. Full article

(This article belongs to the Special Issue Emerging Infectious Diseases in Aquaculture)

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12 pages, 1588 KiB

Open AccessArticle

Identification and Genome Analysis of Vibrio coralliilyticus Causing Mortality of Pacific Oyster (Crassostrea gigas) Larvae

by Hyoun Joong Kim, Jin Woo Jun, Sib Sankar Giri, Cheng Chi, Saekil Yun, Sang Guen Kim, Sang Wha Kim, Se Jin Han, Jun Kwon, Woo Taek Oh, Sung Bin Lee, Ji Hyung Kim and Se Chang Park

Pathogens 2020, 9(3), 206; https://doi.org/10.3390/pathogens9030206 - 11 Mar 2020

Cited by 14 | Viewed by 3784

Abstract

Vibrio coralliilyticus is known as a coral pathogen that also infects marine bivalve larvae worldwide. It is considered to be one of the major constraints in artificial marine bivalve seed production as it causes mortality. In this study, we first isolated and characterized [...] Read more.

Vibrio coralliilyticus is known as a coral pathogen that also infects marine bivalve larvae worldwide. It is considered to be one of the major constraints in artificial marine bivalve seed production as it causes mortality. In this study, we first isolated and characterized a high virulent of V. coralliilyticus designated as SNUTY-1 that was the cause of Pacific oyster larvae mortality in Korea. In the pathogenicity test, exposure to 2.14 × 10⁵ CFU/mL for 24 h caused mortality to 88.65 ± 2.4% of the tested healthy Pacific oyster larvae. SNUTY-1 showed anti-microbial resistance to β-lactams, such as penicillins, cephalosporins, and carbapenems. We sequenced and assembled the complete genome of SNUTY-1 (5,842,676 bp), consisting of two chromosomes (Chr I and Chr II) and two plasmids (pSNUTY1 and pSNUTY2). The COG functional analysis confirmed that Chr I had more genes associated with basic cellular functions in comparison to Chr II. The results of the phylogenetic trees based on OrthoANI values indicated that the SNUTY-1 was closely related to V. coralliilyticus strains. SNUTY-1 had a unique plasmid (pSNUTY2), which could mean that the Korean isolate is different from other sequenced V. coralliilyticus strains from different geographical origins. Toxic proteins such as cytolysin/hemolysin and extracellular metalloprotease genes were encoded on Chr I and Chr II of SNUTY-1. These data facilitate the control of V. coralliilyticus infections in aquaculture by providing valuable insights into the biodiversity of this organism and valuable information for the study of virulence factors. Full article

(This article belongs to the Special Issue Emerging Infectious Diseases in Aquaculture)

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15 pages, 1712 KiB

Open AccessArticle

The B Subunit of PirAB^vp Toxin Secreted from Vibrio parahaemolyticus Causing AHPND Is an Amino Sugar Specific Lectin

by Marcelo Victorio-De Los Santos, Norberto Vibanco-Pérez, Sonia Soto-Rodriguez, Ali Pereyra, Edgar Zenteno and Patricia Cano-Sánchez

Pathogens 2020, 9(3), 182; https://doi.org/10.3390/pathogens9030182 - 3 Mar 2020

Cited by 16 | Viewed by 4446

Abstract

Vibrio parahaemolyticus (Vp) is the etiological agent of the acute hepatopancreatic necrosis disease (AHPND) in Penaeus vannamei shrimp. Vp possesses a 63–70 kb conjugative plasmid that encodes the binary toxin PirA^vp/PirB^vp. The 250 kDa PirAB^vp complex [...] Read more.

Vibrio parahaemolyticus (Vp) is the etiological agent of the acute hepatopancreatic necrosis disease (AHPND) in Penaeus vannamei shrimp. Vp possesses a 63–70 kb conjugative plasmid that encodes the binary toxin PirA^vp/PirB^vp. The 250 kDa PirAB^vp complex was purified by affinity chromatography with galactose-sepharose 4B and on a stroma from glutaraldehyde-fixed rat erythrocytes column, as a heterotetramer of PirA^vp and PirB^vp subunits. In addition, recombinant pirB (rPirB^vp) and pirA (rPirA^vp) were obtained. The homogeneity of the purified protein was determined by SDS-PAGE analysis, and the yield of protein was 488 ng/100 μg of total protein of extracellular products. The PirAB^vp complex and the rPirB^vp showed hemagglutinating activity toward rat erythrocytes. The rPirA^vp showed no hemagglutinating capacity toward the animal red cells tested. Among different mono and disaccharides tested, only GalNH₂ and GlcNH₂ were able to inhibit hemagglutination of the PirAB^vp complex and the rPirB^vp. Glycoproteins showed inhibitory specificity, and fetuin was the glycoprotein that showed the highest inhibition. Other glycoproteins, such as mucin, and glycosaminoglycans, such as heparin, also inhibited the activity. Desialylation of erythrocytes enhanced the hemagglutinating activity. This confirms that Gal or Gal (β1,4) GlcNAc are the main ligands for PirAB^vp. The agglutinating activity of the PirAB^vp complex and the rPirB^vp is not dependent on cations, because addition of Mg²⁺ or Ca²⁺ showed no effect on the protein capacity. Our results strongly suggest that the PirB^vp subunit is a lectin, which is part of the PirA/PirB^vp complex, and it seems to participate in bacterial pathogenicity. Full article

(This article belongs to the Special Issue Emerging Infectious Diseases in Aquaculture)

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18 pages, 2232 KiB

Open AccessArticle

Multilocus Sequence Typing (MLST) and Random Polymorphic DNA (RAPD) Comparisons of Geographic Isolates of Neoparamoeba perurans, the Causative Agent of Amoebic Gill Disease

by Jessica C. Johnson-Mackinnon, Philip B. B. Crosbie, Egil Karlsbakk, Mar Marcos-Lopez, Richard Paley, Barbara F. Nowak and Andrew R. Bridle

Pathogens 2019, 8(4), 244; https://doi.org/10.3390/pathogens8040244 - 19 Nov 2019

Cited by 1 | Viewed by 3628

Abstract

Neoparamoba perurans, is the aetiological agent of amoebic gill disease (AGD), a disease that affects farmed Atlantic salmon worldwide. Multilocus sequence typing (MLST) and Random Amplified Polymorphic DNA (RAPD) are PCR-based typing methods that allow for the highly reproducible genetic analysis of [...] Read more.

Neoparamoba perurans, is the aetiological agent of amoebic gill disease (AGD), a disease that affects farmed Atlantic salmon worldwide. Multilocus sequence typing (MLST) and Random Amplified Polymorphic DNA (RAPD) are PCR-based typing methods that allow for the highly reproducible genetic analysis of population structure within microbial species. To the best of our knowledge, this study represents the first use of these typing methods applied to N. perurans with the objective of distinguishing geographical isolates. These analyses were applied to a total of 16 isolates from Australia, Canada, Ireland, Scotland, Norway, and the USA. All the samples from Australia came from farm sites on the island state of Tasmania. Genetic polymorphism among isolates was more evident from the RAPD analysis compared to the MLST that used conserved housekeeping genes. Both techniques consistently identified that isolates of N. perurans from Tasmania, Australia were more similar to each other than to the isolates from other countries. While genetic differences were identified between geographical isolates, a BURST analysis provided no evidence of a founder genotype. This suggests that emerging outbreaks of AGD are not due to rapid translocation of this important salmonid pathogen from the same area. Full article

(This article belongs to the Special Issue Emerging Infectious Diseases in Aquaculture)

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10 pages, 1092 KiB

Open AccessArticle

Janthinobacterium lividum as An Emerging Pathogenic Bacterium Affecting Rainbow Trout (Oncorhynchus mykiss) Fisheries in Korea

by Woo Taek Oh, Sib Sankar Giri, Saekil Yun, Hyoun Joong Kim, Sang Guen Kim, Sang Wha Kim, Jeong Woo Kang, Se Jin Han, Jun Kwon, Jin Woo Jun and Se Chang Park

Pathogens 2019, 8(3), 146; https://doi.org/10.3390/pathogens8030146 - 11 Sep 2019

Cited by 18 | Viewed by 4542

Abstract

Janthinobacterium spp. are normally considered non-pathogenic, and few pathogenesis-related studies have been reported. Here, we report the first isolation of Janthinobacterium lividum in Korea as a pathogenic bacterium infecting rainbow trout. Mass mortality was observed at one rainbow trout hatchery, and dead fish [...] Read more.

Janthinobacterium spp. are normally considered non-pathogenic, and few pathogenesis-related studies have been reported. Here, we report the first isolation of Janthinobacterium lividum in Korea as a pathogenic bacterium infecting rainbow trout. Mass mortality was observed at one rainbow trout hatchery, and dead fish were necropsied. Gram-negative, nonmotile, rod-shaped bacteria that grew on Cytophaga agar were isolated. A specific violet pigmentation was observed after 7 days of cultivation, and the species were characterized on the basis of the analysis of the 16S rRNA gene. Because no research has focused so far on the pathogenicity of these bacteria, our study was directed to their pathogenic role based on infection-induced histopathology. Examination of stained tissue sections revealed severe renal bacteraemia and tubule degeneration. Other tissue sections, including sections from the liver and the spleen, were relatively clear. The measured half-maximal lethal dose (LD₅₀) was approximately 3 × 10⁵ colony-forming units/fish, suggesting that this bacterium may be an opportunistic pathogen in rainbow trout fisheries. Since the bacterium commonly dwells in soil and most water for rainbow trout fisheries in Korea is supplied from ground water, the bacteria may naturally flow into the aquatic environment. Therefore, recognition of any pathogenic role of J. lividum is important for the prevention of disease in aquaculture. Full article

(This article belongs to the Special Issue Emerging Infectious Diseases in Aquaculture)

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