RESUMEN
Although the genus Aeromonas inhabits the natural environment, it has also been isolated from hospital patient specimens as a causative agent of Aeromonas infections. However, it is not known whether clinical strains live in the natural environment, and if these strains have acquired antimicrobial resistance. In this study, we performed the typing of flagellin A gene (flaA) of clinical and environmental strains of Aeromonas hydrophila and A. veronii biovar sobria using Polymerase Chain Reaction (PCR) assay with newly designed primers. Detection rates of the clinical and environmental flaA types of A. hydrophila were 66.7% and 88.2%, and the corresponding rates for A. veronii biovar sobria were 66.7% and 90.9%. The PCR assays could significantly discriminate between clinical and environmental strains of both species in approximately 4 h. Also, among the 63 clinical Aeromonas strains used, only one extended-spectrum ß-lactamase-producing bacteria, no plasmid-mediated quinolone resistance bacteria, and only four multidrug-resistant bacteria were detected. Therefore, the PCR assays could be useful for the rapid diagnosis of these Aeromonas infections and the monitoring of clinical strain invasion into water-related facilities and environments. Also, the frequency of drug-resistant Aeromonas in clinical isolates from Okinawa Prefecture, Japan, appeared to be low.
Asunto(s)
Aeromonas hydrophila , Flagelina , Infecciones por Bacterias Gramnegativas , Reacción en Cadena de la Polimerasa , Aeromonas hydrophila/genética , Aeromonas hydrophila/efectos de los fármacos , Aeromonas hydrophila/aislamiento & purificación , Humanos , Infecciones por Bacterias Gramnegativas/microbiología , Reacción en Cadena de la Polimerasa/métodos , Flagelina/genética , Aeromonas veronii/genética , Aeromonas veronii/aislamiento & purificación , Aeromonas veronii/efectos de los fármacos , Farmacorresistencia Bacteriana/genética , Antibacterianos/farmacología , Pruebas de Sensibilidad Microbiana , Microbiología AmbientalRESUMEN
Bacterial pathogens cause high fish mortalities and in turn economic losses in fish farms. Innovative strategies should be applied to control bacterial infections instead of antibiotics to avoid the resistance problem. Consequently, the present investigation studied the curative potential of Azadirachta indica leave ethanolic extract (AILEE) on Aeromonas veronii infection in Oreochromis niloticus. A preliminary trial was assessed to evaluate the curative dose of AILEE which was found to be 2.5 mg/L. One hundred and sixty fish were divided into equal four groups in four replications, where group 1 and group 2 were non-challenged and treated with 0- and 2.5-mg/L AILEE, respectively. Group 3 and group 4 were challenged with A. veronii and treated with 0- and 2.5-mg/L AILEE, respectively for 10 days. A. veronii infection produced severe clinical manifestations and a high mortality rate in the infected fish. Furthermore, the infected fish exhibited a significant rise in the hepatorenal indices (aspartate aminotransferase, alanine aminotransferase, and creatinine), the oxidant biomarker (malondialdehyde), and the stress indicators (glucose and cortisol). A significant reduction in the protein profile and antioxidant/immune parameters (catalase, immunoglobulin M, lysozyme, nitric oxide, and phagocytic activity) was observed in the infected fish. Water application of the infected group to 2.5-mg/L AILEE notably ameliorated the hepatorenal indices, the oxidant biomarker, and the stress indicators. Furthermore, AILEE improved the antioxidant/immune indices. Water application of 2.5-mg/L AILEE could be useful against A. veronii infection in O. niloticus culture.
Asunto(s)
Aeromonas veronii , Azadirachta , Cíclidos , Enfermedades de los Peces , Infecciones por Bacterias Gramnegativas , Extractos Vegetales , Hojas de la Planta , Animales , Azadirachta/química , Extractos Vegetales/farmacología , Extractos Vegetales/química , Enfermedades de los Peces/tratamiento farmacológico , Enfermedades de los Peces/microbiología , Infecciones por Bacterias Gramnegativas/veterinaria , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Aeromonas veronii/efectos de los fármacos , Hojas de la Planta/química , Etanol/químicaRESUMEN
Aeromonas spp. are associated with seafood-related outbreaks worldwide. In seafood industry, shellfish play a major role in global seafood production. With this emerging trend of shellfish consumption, shellfish-related bacterial infections are being reported frequently. Aeromonas spp. are natural contaminants found in shellfish. Although 36 species have been identified, some species including Aeromonas hydrophila, Aeromonas caviae and Aeromonas veronii biotype sobria have dragged major attention as foodborne pathogenic bacteria. The ability to elaborate a variety of virulence factors of Aeromonas spp. contributes to the pathogenic activities. Also, emerging antimicrobial resistance in Aeromonas spp. has become a huge challenge in seafood industry. Furthermore, multidrug resistance increases the risk of consumer health. Studies have supplied pieces of evidence about the emerging health risk of Aeromonas spp. isolated from seafood. Therefore, the present review was intended to highlight the prevalence, virulence and antimicrobial resistance of Aeromonas spp. isolated from various types of shellfish.
Asunto(s)
Aeromonas/efectos de los fármacos , Aeromonas/patogenicidad , Farmacorresistencia Bacteriana , Mariscos/microbiología , Virulencia , Aeromonas caviae/efectos de los fármacos , Aeromonas caviae/patogenicidad , Aeromonas hydrophila/efectos de los fármacos , Aeromonas hydrophila/patogenicidad , Aeromonas veronii/efectos de los fármacos , Aeromonas veronii/patogenicidad , Animales , Antibacterianos/farmacología , Biopelículas , Contaminación de Alimentos , Microbiología de Alimentos , Humanos , Prevalencia , Alimentos Marinos/microbiología , Factores de VirulenciaRESUMEN
Despite progress achieved, there is limited available information about the antibacterial activity of constituents of essential oils (EOs) from different medicinal-aromatic plants (MAPs) against fish pathogens and the complex interactions of blended EOs thereof. The present study aimed to investigate possible synergistic antimicrobial effects of EOs from seven Greek MAPs with strong potential against Aeromonas veronii bv. sobria, a fish pathogen associated with aquaculture disease outbreaks. The main objective was to evaluate whether blending of these EOs can lead to increased antimicrobial activity against the specific microorganism. A total of 127 combinations of EOs were prepared and their effect on A. veronii bv. sobria growth was tested in vitro. We examined both the inhibitory and bactericidal activities of the individual EOs and compared them to those of the blended EOs. The vast majority of the investigated combinations exhibited significant synergistic and additive effects, while antagonistic effects were evident only in a few cases, such as the mixtures containing EOs from rosemary, lemon balm and pennyroyal. The combination of EOs from Greek oregano and wild carrot, as well as the combinations of those two with Spanish oregano or savoury were the most promising ones. Overall, Greek oregano, savoury and Spanish oregano EOs were the most effective ones when applied either in pure form or blended with other EOs.
Asunto(s)
Aeromonas veronii/efectos de los fármacos , Antibacterianos/farmacología , Peces/microbiología , Infecciones por Bacterias Gramnegativas/prevención & control , Aceites Volátiles/farmacología , Extractos Vegetales/farmacología , Animales , Apiaceae , Técnicas de Química Sintética , Daucus carota , Sinergismo Farmacológico , Cromatografía de Gases y Espectrometría de Masas , Infecciones por Bacterias Gramnegativas/veterinaria , Concentración 50 Inhibidora , Melissa , Mentha , Pruebas de Sensibilidad Microbiana , Origanum , Plantas Medicinales/química , Rosmarinus , SaturejaRESUMEN
Aeromonas veronii is one of the main pathogens causing various diseases in humans and animals. It is currently difficult to eradicate drug-resistant A. veronii due to the biofilm formation by conventional antibiotic treatments. In this study, a marine peptide-N6NH2 and its analogs were generated by introducing Orn or replacing with D-amino acids, Val and Pro; their enzymic stability and antibacterial/antibiofilm ability against multi-drug resistant (MDR) A. veronii ACCC61732 were detected in vitro and in vivo, respectively. The results showed that DN6NH2 more rapidly killed A. veronii ACCC61732 and had higher stability in trypsin, simulated gastric/intestinal fluid, proteinase K, and mouse serum than the parent peptide-N6NH2. DN6NH2 and other analogs significantly improved the ability of N6NH2 to penetrate the outer membrane of A. veronii ACCC61732. DN6NH2, N6PNH2 and V112N6NH2 protected mice from catheter-associated biofilm infection with MDR A. veronii ACCC61732, superior to N6NH2 and CIP. DN6NH2 had more potent efficacy at a dose of 5 µmol/kg (100% survival) in a mouse peritonitis model than other analogs (50-66.67%) and CIP (83.33%), and it inhibited the bacterial translocation, downregulated pro-inflammatory cytokines, upregulated the anti-inflammatory cytokine, and ameliorated multiple-organ injuries (including the liver, spleen, lung, and kidney). These data suggest that the analogs of N6NH2 may be a candidate for novel antimicrobial and antibiofilm agents against MDR A. veronii infections.
Asunto(s)
Aeromonas veronii/efectos de los fármacos , Antibacterianos/farmacología , Biopelículas/crecimiento & desarrollo , Resistencia a Múltiples Medicamentos/efectos de los fármacos , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Insuficiencia Multiorgánica/tratamiento farmacológico , Úlcera Cutánea/tratamiento farmacológico , Aeromonas veronii/crecimiento & desarrollo , Animales , Biopelículas/efectos de los fármacos , Femenino , Infecciones por Bacterias Gramnegativas/complicaciones , Infecciones por Bacterias Gramnegativas/microbiología , Ratones , Ratones Endogámicos ICR , Pruebas de Sensibilidad Microbiana , Insuficiencia Multiorgánica/complicaciones , Insuficiencia Multiorgánica/microbiología , Úlcera Cutánea/complicaciones , Úlcera Cutánea/microbiologíaRESUMEN
Pathogenic Aeromonas veronii results in great healthy and economic losses in fishes and human. The multiple drug tolerance of bacterial persister is the major cause for recurrent infections. Ubiquitous RNA-binding protein Hfq is liable for antibiotic tolerance and persisiter production. We showed that the hfq deletion in A. veronii retarded the growth, reduced the tolerances to diverse antibiotics, and lowered the persistence. Such effects might be mediated by the downregulations of RelE, CspD, ClpB, RpoS, OxyR, and upregulation of OppB. Our study supports the role of Hfq in persister formation and provides clues for the avoidance of recalcitrant infections.
Asunto(s)
Aeromonas veronii/crecimiento & desarrollo , Aeromonas veronii/genética , Antibacterianos/farmacología , Proteína de Factor 1 del Huésped/genética , Proteína de Factor 1 del Huésped/fisiología , Aeromonas veronii/efectos de los fármacos , Farmacorresistencia Bacteriana/genética , Eliminación de Gen , Regulación Bacteriana de la Expresión Génica , Genes Bacterianos/genética , Pruebas de Sensibilidad Microbiana , ARN , Transcriptoma , Virulencia/genéticaRESUMEN
Aeromonas veronii is an important type of gram-negative pathogen of human-livestock-aquatic animal and causes great economic losses in the aquaculture industry. Vaccination is an effective method of defence against A. veronii. There are many factors that restrict the use of vaccination, and the development of new oral vaccines is urgently needed. The selection of suitable antigens is of great significance for the development of aquaculture vaccines. Bacterial flagellin can specifically bind to TLR5 and induce the release of cytokines from the organism, which could be used in the development of vaccines. In this study, we constructed two recombinant Lactobacillus casei (L. casei) (surface-displayed or secretory) expressing the flaB of A. veronii and evaluated the effect of immune responses in common carp. The flaB gene (900 bp) of A. veronii was subcloned into the L. casei expression plasmids pPG-1 (surface-displayed) and pPG-2 (secretory). Western blot and immunofluorescence assays confirmed the expression of the recombinant flaB protein. Common carp immunized with Lc-pPG-1-flaB and Lc-pPG-2-flaB via oral administration route exhibited induction of antibody expression and innate immune responses. The results indicated that Lc-pPG-1-flaB and Lc-pPG-2-flaB can induce high levels of IgM, ACP, AKP, LZM and SOD activity in organisms, and Lc-pPG-1-flaB can induce even higher levels. The recombinant L. casei may effectively induce humoral immunity and increase the serum immunological index. Furthermore, leukocytes phagocytosis percentage and index of the recombinant L. casei were enhanced. The results of qRT-PCR showed that recombinant L. casei can significantly increase the expression of IL-10, IL-ß, IFN-γ and TNF-α in the tissues of immunized common carp, compared with control groups. Viable recombinant L. casei strains, which were delivered directly survived throughout the intestinal tract. Common carp that received Lc-pPG-1-flaB (66.7%) and Lc-pPG-2-flaB (53.3%) exhibited higher survival rates than the controls after challenge with the pathogen A. veronii. Our work indicated that Lc-pPG-1-flaB and Lc-pPG-2-flaB had beneficial effects on immune response and enhanced the disease resistance of common carp against A. veronii infection. The combination of flaB delivery and the Lactic acid bacteria (LAB) approach may be a promising method for the development of oral vaccines for treating A. veronii. In future research, we will focus on the colonization ability of LAB in the intestines and on the impact of these bacteria on intestinal flora.
Asunto(s)
Aeromonas veronii/efectos de los fármacos , Vacunas Bacterianas/inmunología , Carpas/inmunología , Flagelina/farmacología , Inmunización/veterinaria , Inmunogenicidad Vacunal/inmunología , Lacticaseibacillus casei/inmunología , Administración Oral , Animales , Anticuerpos Antibacterianos/inmunología , Formación de Anticuerpos/inmunología , Flagelina/administración & dosificación , Vacunas Sintéticas/inmunologíaRESUMEN
Bacterial persisters comprise a small fraction of phenotypically heterogeneous variants with transient capability for survival when exposed to high concentrations of antibiotic. In aquatic pathogenic bacteria Aeromonas veronii, Small Protein B (SmpB), the core factor of trans-translation system, was identified as a new persistence-related gene. The SmpB deletion exhibited a higher susceptibility and lower persister cell formation under aminoglycosides antibiotics pressure compared with wild type. The transcriptional and translational activities of smpB gene were significantly enhanced by the gentamicin challenge in exponential phase, but not changed in stationary phase. The transcriptomic analysis revealed that the smpB deletion stimulated the production of proton-motive force (PMF). The cell survival induced by carbonyl cyanide m-chlorophenyl hydrazone (CCCP) further verified that SmpB variation affected the quantities of PMF. Taken together, these results uncovered a novel mechanism of persister formation mediated by SmpB under aminoglycosides treatments.
Asunto(s)
Aeromonas veronii/metabolismo , Aminoglicósidos/farmacología , Regulación hacia Abajo/efectos de los fármacos , Fuerza Protón-Motriz/efectos de los fármacos , Proteínas de Unión al ARN/metabolismo , Aeromonas veronii/efectos de los fármacos , Antibacterianos/farmacología , Transporte de Electrón/efectos de los fármacos , Eliminación de Gen , Gentamicinas/farmacología , Pruebas de Sensibilidad Microbiana , Biosíntesis de Proteínas/efectos de los fármacosRESUMEN
Unusual persistent natural mortality occurred in a floating in-pond raceway system intensively stocked with channel and hybrid catfish beginning in early November 2016 up until March 2017. The temperature during the period of outbreak ranged from 7.2 to 23.7°C. Gross examination of freshly dead and moribund fish revealed pale gills, slight abdominal distension and swollen inflamed vents. Comprehensive necropsy of 20 fish demonstrated vast amounts of bloody ascitic fluid in the coelomic cavity, visceral congestion, splenomegaly and pale friable livers but macroscopically normal kidneys, suggesting systemic bacterial infection. Bacterial cultures were initiated from skin, gills and major internal organs. Following incubation, a mixture of three bacterial colony phenotypes was observed on agar plates. Presumptive biochemical characterization of the isolates followed by 16S-rRNA sequence analysis resulted in the identification of Aeromonas veronii, Streptococcus parauberis and Shewanella putrefaciens. Channel catfish juveniles were experimentally infected with the recovered isolates to fulfil Koch's postulates. Moreover, an antibiogram was used to evaluate the susceptibility of the isolates to antimicrobial drugs approved for use in aquaculture. Aquaflor was used successfully for treatment. Here, we report bacterial coinfection lead by A. veronii and the first identification of S. parauberis and S. putrefaciens from cultured catfish in North America.
Asunto(s)
Bacterias/aislamiento & purificación , Coinfección/microbiología , Enfermedades de los Peces/microbiología , Infecciones por Bacterias Gramnegativas/veterinaria , Infecciones por Bacterias Grampositivas/veterinaria , Ictaluridae/microbiología , Estaciones del Año , Aeromonas veronii/efectos de los fármacos , Aeromonas veronii/genética , Aeromonas veronii/aislamiento & purificación , Aeromonas veronii/fisiología , Animales , Antiinfecciosos/farmacología , Acuicultura , Enfermedades de los Peces/epidemiología , Infecciones por Bacterias Gramnegativas/sangre , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Infecciones por Bacterias Gramnegativas/mortalidad , Infecciones por Bacterias Grampositivas/sangre , Infecciones por Bacterias Grampositivas/tratamiento farmacológico , Infecciones por Bacterias Grampositivas/mortalidad , América del Norte/epidemiología , Estanques/microbiología , Propofol/administración & dosificación , Propofol/farmacología , Propofol/uso terapéutico , ARN Ribosómico 16S/genética , Shewanella putrefaciens/efectos de los fármacos , Shewanella putrefaciens/genética , Shewanella putrefaciens/aislamiento & purificación , Infecciones Estreptocócicas/veterinaria , Streptococcus/efectos de los fármacos , Streptococcus/genética , Streptococcus/aislamiento & purificación , Streptococcus/fisiologíaRESUMEN
Two adjacent colistin resistance gene variants, termed mcr-3.3 and mcr-3-like, were identified in the chromosome of an Aeromonas veronii isolate obtained from retail chicken meat. The variants showed 95.20% and 84.19% nucleotide sequence identity, respectively, to mcr-3 from porcine Escherichia coli Functional cloning indicated that only mcr-3.3 conferred polymyxin resistance in both E. coli and Aeromonas salmonicida The mcr-3.3-mcr-3-like segment was also observed in other Aeromonas species, including A. media, A. caviae, and A. hydrophila.
Asunto(s)
Aeromonas veronii/efectos de los fármacos , Aeromonas veronii/genética , Pollos/microbiología , Farmacorresistencia Bacteriana/genética , Aeromonas veronii/aislamiento & purificación , Animales , Antibacterianos/farmacología , Proteínas Bacterianas/genética , China , Cromosomas Bacterianos , Clonación Molecular , Colistina/farmacología , Farmacorresistencia Bacteriana/efectos de los fármacos , Microbiología de Alimentos , Pruebas de Sensibilidad Microbiana , Polimixinas/farmacologíaRESUMEN
Aeromonas species are important pathogens of fishes and aquatic animals capable of infecting humans and other animals via food. Due to the paucity of pan-genomic studies on aeromonads, the present study was undertaken to analyse the pan-genome of three clinically important Aeromonas species (A. hydrophila, A. veronii, A. caviae). Results of pan-genome analysis revealed an open pan-genome for all three species with pan-genome sizes of 9181, 7214 and 6884 genes for A. hydrophila, A. veronii and A. caviae, respectively. Core-genome: pan-genome ratio (RCP) indicated greater genomic diversity for A. hydrophila and interestingly RCP emerged as an effective indicator to gauge genomic diversity which could possibly be extended to other organisms too. Phylogenomic network analysis highlighted the influence of homologous recombination and lateral gene transfer in the evolution of Aeromonas spp. Prediction of virulence factors indicated no significant difference among the three species though analysis of pathogenic potential and acquired antimicrobial resistance genes revealed greater hazards from A. hydrophila. In conclusion, the present study highlighted the usefulness of whole genome analyses to infer evolutionary cues for Aeromonas species which indicated considerable phylogenomic diversity for A. hydrophila and hitherto unknown genomic evidence for pathogenic potential of A. hydrophila compared to A. veronii and A. caviae.
Asunto(s)
Aeromonas caviae/genética , Aeromonas hydrophila/genética , Aeromonas veronii/genética , Aeromonas caviae/efectos de los fármacos , Aeromonas caviae/patogenicidad , Aeromonas hydrophila/efectos de los fármacos , Aeromonas hydrophila/patogenicidad , Aeromonas veronii/efectos de los fármacos , Aeromonas veronii/patogenicidad , Animales , Antibacterianos/farmacología , Farmacorresistencia Microbiana , Evolución Molecular , Transferencia de Gen Horizontal , Variación Genética , Genoma Bacteriano , Genotipo , Recombinación Homóloga , Humanos , Pruebas de Sensibilidad Microbiana , Filogenia , Virulencia/genética , Factores de Virulencia/genéticaRESUMEN
Aeromonas spp. are frequently encountered in aquatic environments, with Aeromonas veronii emerging as an opportunistic pathogen causing a range of diseases in both humans and animals. Recent reports have raised public health concerns due to the emergence of multidrug-resistant Aeromonas spp. This is particularly noteworthy as these species have demonstrated the ability to acquire and transmit antimicrobial resistance genes (ARGs). In this study, we report the genomic and phenotypic characteristics of the A. veronii TR112 strain, which harbors a novel variant of the Vietnamese Extended-spectrum ß-lactamase-encoding gene, blaVEB-28, and two mcr variants recovered from an urban river located in the Metropolitan Region of São Paulo, Brazil. A. veronii TR112 strain exhibited high minimum inhibitory concentrations (MICs) for ceftazidime (64 µg/mL), polymyxin (8 µg/mL), and ciprofloxacin (64 µg/mL). Furthermore, the TR112 strain demonstrated adherence to HeLa and Caco-2 cells within 3 h, cytotoxicity to HeLa cells after 24 h of interaction, and high mortality rates to the Galleria mellonella model. Genomic analysis showed that the TR112 strain belongs to ST257 and presented a range of ARGs conferring resistance to ß-lactams (blaVEB-28, blaCphA3, blaOXA-912) and polymyxins (mcr-3 and mcr-3.6). Additionally, we identified a diversity of virulence factor-encoding genes, including those encoding mannose-sensitive hemagglutinin (Msh) pilus, polar flagella, type IV pili, type II secretion system (T2SS), aerolysin (AerA), cytotoxic enterotoxin (Act), hemolysin (HlyA), hemolysin III (HlyIII), thermostable hemolysin (TH), and capsular polysaccharide (CPS). In conclusion, our findings suggest that A. veronii may serve as an environmental reservoir for ARGs and virulence factors, highlighting its importance as a potential pathogen in public health.
Asunto(s)
Aeromonas veronii , Antibacterianos , Pruebas de Sensibilidad Microbiana , Ríos , beta-Lactamasas , beta-Lactamasas/genética , beta-Lactamasas/metabolismo , Humanos , Antibacterianos/farmacología , Ríos/microbiología , Aeromonas veronii/genética , Aeromonas veronii/aislamiento & purificación , Aeromonas veronii/efectos de los fármacos , Brasil , Células HeLa , Células CACO-2 , Animales , Farmacorresistencia Bacteriana Múltiple/genéticaRESUMEN
Aeromonas veronii, a significant pathogen in aquatic environments, poses a substantial threat to both human and animal health, particularly in aquaculture. In this study, we isolated A. veronii strain GD2019 from diseased largemouth bass (Micropterus salmoides) during a severe outbreak of aeromonad septicemia in Guangdong Province, China. The complete genome sequence of A. veronii GD2019 revealed that GD2019 contains a single chromosome of 4703,168â¯bp with an average G+C content of 58.3%. Phylogenetic analyses indicated that GD2019 forms a separate sub-branch in A. veronii and comparative genomic analyses identified the existence of an intact Type III secretion system. Moreover, to investigate the genes that are required for the conditional fitness of A. veronii under various stresses, a high-density transposon insertion library in GD2019 was generated by a Tn5-based transposon and covers 6311 genomic loci including 4155 genes and 2156 intergenic regions. Leveraging this library, 630 genes were classified as essential genes for growth in rich-nutrient LB medium. Furthermore, the genes GE001863/NtrC and GE002550 were found to confer tolerance to sodium hypochlorite in A. veronii. GE002562 and GE002614 were associated with the resistance to carbenicillin. Collectively, our results provide abundant genetic information on A. veronii, shedding light on the pathogenetic mechanisms of Aeromonas.
Asunto(s)
Aeromonas veronii , Elementos Transponibles de ADN , Farmacorresistencia Bacteriana , Enfermedades de los Peces , Genoma Bacteriano , Filogenia , Hipoclorito de Sodio , Secuenciación Completa del Genoma , Aeromonas veronii/genética , Aeromonas veronii/efectos de los fármacos , Elementos Transponibles de ADN/genética , Animales , Hipoclorito de Sodio/farmacología , Farmacorresistencia Bacteriana/genética , Enfermedades de los Peces/microbiología , China , Infecciones por Bacterias Gramnegativas/microbiología , Lubina/microbiología , Antibacterianos/farmacología , Composición de Base , Mutagénesis InsercionalRESUMEN
Flumequine was nano-immobilized by self-assembly on iron oxide nanoparticles, called surface active maghemite nanoparticles (SAMNs). The binding process was studied and the resulting core-shell nanocarrier (SAMN@FLU) was structurally characterized evidencing a firmly immobilized organic canopy on which the fluorine atom of the antibiotic was exposed to the solvent. The antibiotic efficacy of the SAMN@FLU nanocarrier was tested on a fish pathogenic bacterium (Aeromonas veronii), a flumequine sensitive strain, in comparison to soluble flumequine and the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were assessed. Noteworthy, the MIC and MBC of soluble and nanoparticle bound drug were superimposable. Moreover, the interactions between SAMN@FLU nanocarrrier and microorganism were studied by transmission electron microscopy evidencing the ability of the complex to disrupt the bacterial wall. Finally, a preliminary in vivo test was provided using Daphnia magna as animal model. SAMN@FLU was able to protect the crustacean from the fatal consequences of a bacterial infection and showed no sign of toxicity. Thus, in contrast with the strength of the interaction, nano-immobilized FLU displayed a fully preserved antimicrobial activity suggesting the crucial role of fluorine in the drug mechanism of action. Besides the importance for potential applications in aquaculture, the present study contributes to the nascent field of nanoantibiotics.
Asunto(s)
Aeromonas veronii/efectos de los fármacos , Antibacterianos/farmacología , Daphnia/efectos de los fármacos , Fluoroquinolonas/farmacología , Nanopartículas de Magnetita/química , Animales , Antibacterianos/química , Daphnia/microbiología , Fluoroquinolonas/química , Pruebas de Sensibilidad Microbiana , Estructura MolecularRESUMEN
Bacterial persisters are a small proportion of phenotypically heterogeneous variants with the transient capability to survive in high concentrations of antibiotics, causing recurrent infections in both human and aquatic animals. Transfer-messenger RNA (tmRNA), which was encoded by the ssrA gene, was identified as a determinant regulator mediating the persistence to ß-lactams in the pathogenic Aeromonas veronii C4. The deletion of tmRNA exhibited the increased ability of persister formation most probably due to the reduction of protein synthesis. Transcriptomic and metabolomic analyses revealed that the absence of tmRNA not only significantly elevated the intercellular levels of metabolite GlcNAc and promoted NaCl osmotic tolerance, but also upregulated the expression of metabolic genes in both the upstream biosynthesis pathway and the downstream metabolic flux of peptidoglycan (PG) biosynthesis. Finally, exogenous GlcNAc stimulated significant bacterial growth, enhanced content of GlcNAc in the cell wall, higher resistance to osmotic response, and higher persistence to cefotaxime in a concentration-dependent manner, implying its potential role in promoting the multiple phenotypes observed in tmRNA deletion strains. Taken together, these results hint at a potential mechanism of persister formation mediated by tmRNA against the ß-lactam challenges in A. veronii.
Asunto(s)
Acetilglucosamina/metabolismo , Aeromonas veronii/genética , Aeromonas veronii/metabolismo , Cefotaxima/farmacología , ARN Bacteriano/genética , Aeromonas veronii/efectos de los fármacos , Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple/genética , Regulación Bacteriana de la Expresión Génica , Pruebas de Sensibilidad Microbiana , Osmorregulación , Peptidoglicano/metabolismo , Biosíntesis de Proteínas , Regulación hacia Arriba , beta-Lactamas/farmacologíaRESUMEN
Aeromonas are bacteria widely distributed in the environment, and some species are able to cause infections in humans, of which diarrhea is the most common. The objective of this study was to evaluate the presence of virulence and antimicrobial resistance associated characteristics in A. veronii biovar sobria strain 312M isolated from diarrheal stools. For this, the genome sequencing and phenotypical tests were performed. The draft genome annotation revealed several complete pathways associated with carbon metabolism and a mucin-desulfating sulfatase which may contribute to intestine colonization, and a large number of virulence-associated genes encoding structures associated with adhesion, toxins, and secretion systems. The strain exhibited swimming and swarming motility, biofilm formation, and hemolytic activity. It was resistant to ampicillin, ampicillin/sulbactam, and amoxicillin-clavulanic acid. Although a cphA gene encoding a narrow-spectrum carbapenase was identified in the strain genome, no carbapenemase activity was detected in the antimicrobial susceptibility test. When compared with other A. veronii with complete genomes, the main differences in virulence characteristics are related to lateral flagella and type III and VI secretion systems; the antimicrobial resistance spectrum also varied among strains. The results indicated that A. veronii biovar sobria 312M presents high virulence potential and resistance to limited classes of antimicrobials.
Asunto(s)
Aeromonas veronii/efectos de los fármacos , Aeromonas veronii/genética , Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple , Factores de Virulencia/genética , Aeromonas veronii/patogenicidad , Biopelículas/crecimiento & desarrollo , Diarrea/microbiología , Heces/microbiología , Infecciones por Bacterias Gramnegativas/microbiología , Humanos , Pruebas de Sensibilidad Microbiana , Virulencia , Secuenciación Completa del GenomaRESUMEN
To emphasize the importance of the appropriate use of antibiotics in aquaculture systems, the prevalence of resistance to 25 antimicrobials was investigated in 42 Aeromonas veronii strains isolated from farm-raised channel catfish in China in 2006-2012. All experiments were based on minimal inhibitory concentrations (MICs), and susceptibility was assessed according to the Clinical and Laboratory Standards Institute. Some isolates displayed antibiotic resistance to the latest-generation fluoroquinolones (i.e., ciprofloxacin, levofloxacin, and norfloxacin) in vitro. Therefore, we screened for genes conferring resistance to fluoroquinolones and performed conjugation experiments to establish the resistance mechanisms. The antibiotic resistance rates were 14.29-21.42% to three kinds of fluoroquinolones: ciprofloxacin, levofloxacin, and norfloxacin. Among the 42 strains isolated, 15 carried the qnrS2 gene. The MICs of the fluoroquinolones in transconjugants with qnrS2 were more than fourfold higher compared with the recipient. Among the fluoroquinolone-resistant A. veronii strains, eight had point mutations in both gyrA codon 83 (Ser83âIle83) and parC codon 87 (Ser87âIle87). However, five isolates with point mutations in parC codon 52 remained susceptible to the three fluoroquinolones. In conclusion, the mechanisms of fluoroquinolone resistance in A. veronii isolates may be related to mutations in gyrA codon 83 and parC codon 87 and the presence of the qnrS2 gene.