Abstract:This study determined the minimum inhibitory concentrations (MICs) for oxytetracycline hydrochloride (OTC) and erythromycin (Em), along with the a-glucosidase (a-glu) activities in 110 Nocardia seriolae strains isolated in Miyazaki and Kagoshima prefectures in 2008-2009. The strains were examined for the presence of the tet(K), tet(L), tet(M), tet(O), tet(S), erm(A), erm(B), mph(A), mef(A), and msr(D) genes. All the a-glu-positive strains (n = 15) were OTC resistant and Em sensitive, with MICs of 32-64 and \0.… Show more
“…In the genomes of Nocardia strains, resistance genes against several kinds of antibiotics were detected with more than 30% similarity to previously known antibiotic resistance genes (Figure ). According to Yasuike et al., the N. seriolae strains can be divided into two groups according to their α‐glucosidase activity and susceptibility to erythromycin or oxytetracycline (Ismail, Takeshita, Umeda, Itami, & Yoshida, ; Yasuike et al., ). All N. seriolae strains analyzed in this study contained the gene encoding α‐glucosidase, but did not have resistance genes against erythromycin or oxytetracycline.…”
Section: Resultsmentioning
confidence: 99%
“…Resistance against several kinds of antibiotics is a major feature of the genus Nocardia (Hashemi‐Shahraki et al., ; Ismail et al., ). Pathogens possessing diverse antibiotic resistance genes can cause severe problems, such as the transfer of antibiotic resistance genes to other bacteria and an increase in multi‐drug resistant pathogens.…”
Members of the genus Nocardia are widespread in diverse environments; a wide range of Nocardia species are known to cause nocardiosis in several animals, including cat, dog, fish, and humans. Of the pathogenic Nocardia species, N. seriolae is known to cause disease in cultured fish, resulting in major economic loss. We isolated two N. seriolae strains, CK-14008 and EM15050, from diseased fish and sequenced their genomes using the PacBio sequencing platform. To identify their genomic features, we compared their genomes with those of other Nocardia species. Phylogenetic analysis showed that N. seriolae shares a common ancestor with a putative human pathogenic Nocardia species. Moreover, N. seriolae strains were phylogenetically divided into four clusters according to host fish families. Through genome comparison, we observed that the putative pathogenic Nocardia strains had additional genes for iron acquisition. Dozens of antibiotic resistance genes were detected in the genomes of N. seriolae strains; most of the antibiotics were involved in the inhibition of the biosynthesis of proteins or cell walls. Our results demonstrated the virulence features and antibiotic resistance of fish pathogenic N. seriolae strains at the genomic level. These results may be useful to develop strategies for the prevention of fish nocardiosis.
“…In the genomes of Nocardia strains, resistance genes against several kinds of antibiotics were detected with more than 30% similarity to previously known antibiotic resistance genes (Figure ). According to Yasuike et al., the N. seriolae strains can be divided into two groups according to their α‐glucosidase activity and susceptibility to erythromycin or oxytetracycline (Ismail, Takeshita, Umeda, Itami, & Yoshida, ; Yasuike et al., ). All N. seriolae strains analyzed in this study contained the gene encoding α‐glucosidase, but did not have resistance genes against erythromycin or oxytetracycline.…”
Section: Resultsmentioning
confidence: 99%
“…Resistance against several kinds of antibiotics is a major feature of the genus Nocardia (Hashemi‐Shahraki et al., ; Ismail et al., ). Pathogens possessing diverse antibiotic resistance genes can cause severe problems, such as the transfer of antibiotic resistance genes to other bacteria and an increase in multi‐drug resistant pathogens.…”
Members of the genus Nocardia are widespread in diverse environments; a wide range of Nocardia species are known to cause nocardiosis in several animals, including cat, dog, fish, and humans. Of the pathogenic Nocardia species, N. seriolae is known to cause disease in cultured fish, resulting in major economic loss. We isolated two N. seriolae strains, CK-14008 and EM15050, from diseased fish and sequenced their genomes using the PacBio sequencing platform. To identify their genomic features, we compared their genomes with those of other Nocardia species. Phylogenetic analysis showed that N. seriolae shares a common ancestor with a putative human pathogenic Nocardia species. Moreover, N. seriolae strains were phylogenetically divided into four clusters according to host fish families. Through genome comparison, we observed that the putative pathogenic Nocardia strains had additional genes for iron acquisition. Dozens of antibiotic resistance genes were detected in the genomes of N. seriolae strains; most of the antibiotics were involved in the inhibition of the biosynthesis of proteins or cell walls. Our results demonstrated the virulence features and antibiotic resistance of fish pathogenic N. seriolae strains at the genomic level. These results may be useful to develop strategies for the prevention of fish nocardiosis.
“…0.5 McFarland standard as previously reported (Ismail et al 2011a), and were diluted 100-fold with sterile 0.85% NaCl (10 5 to 10 6 CFU/ml). Cinnamon (Cinnamomum zeylanicum), thyme (Thymus vulgaris), lemongrass (Cymbopogon flexuosus) and tea tree (Melaleuca alternifolia) EOs were obtained from Naturas Psychos (http:// www.naturas-psychos.com) as 100% pure oils.…”
“…The previously proposed environmental selective pressure for the routinely used oxytetracycline (OTC) and erythromycin (Em) antibiotics in the Asian aquaculture resulted in a marked prevalence of the h-glucosidase (glu)-positive N. seriolae that were OTC resistant and Em sensitive in Asian countries, while the h-glu-negative N. seriolae that were OTC sensitive and Em resistant prevailed in Japan (Ismail et al 2011a(Ismail et al , 2011b. For these reasons, the search for antimicrobial safer compounds that have no harmful effects on fish, consumers and the environment is greatly encouraged.…”
Microplate resazurin assay was applied to investigate the in vitro activity of four essential oils (EOs); cinnamon (Cinnamomum zeylanicum), thyme (Thymus vulgaris), lemongrass (Cymbopogon flexuosus) and tea tree (Melaleuca alternifolia) oils against 80 clinical isolates of the fish pathogen Nocardia seriolae. The checkerboard test was then used to determine the possible synergistic effect of EOs combination against reference type strains of fish nocardiosis. All tested EOs had antibacterial activity against N. seriolae isolates. Among the tested EOs, cinnamon and thyme oils both exhibited the lowest minimum inhibitory concentrations (MICs) with 5-160 and 10-160 μg/ml, respectively. The activities of lemongrass and tea tree EOs were noted to be less effective with MICs of 20-640 and 160->5120 μg/ml, respectively. The checkerboard panel of cinnamon-thyme EOs combination against N. seriolae ATCC43993 demonstrated a synergistic effect with a fractional inhibitory concentration (FIC) index of 0.75. For N. salmonicida ATCC27463, the combination panel showed an additive effect with an FIC index of 1.0. For N. asteroides ATCC19247, the combination panel demonstrated an indifference effect with an FIC index of 1.125. These results indicate that thyme and cinnamon oils alone or the combination of them at a given ratio has a promising potent clinical significance in the treatment of fish nocardiosis. Despite the promising results given by our in vitro studies, the clinical benefits of these EOs combinations can only be determined through carefully designed in vivo experimental studies.
“…seriolae causes nocardiosis mainly in cultured yellowtail ( Seriola quinqueradiata ) and amberjack ( Seriola dumerili ) (4), which can be controlled by using sulfamonomethoxine and sulfisozole sodium (http://www.maff.go.jp/j/syouan/suisan/suisan_yobo/). On the other hand, the emergence of resistant strains to macrolide antibiotics (i.e., erythromycin, spiramycin, and kitasamycin) and oxytetracycline has previously been reported (5–7). We isolated seven N .…”
In Japan, the emergence of macrolide- and oxytetracycline-resistant strains of Nocardia seriolae has previously been reported. Here, we describe the draft genome sequence of N. seriolae strain U-1, isolated in 2011 from a diseased yellowtail in Kagoshima Prefecture. The draft genome does not have any genes responsible for macrolide and tetracycline resistance.
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