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1.
World J Microbiol Biotechnol ; 35(8): 127, 2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31375931

RESUMO

Aeromonas hydrophila is a Gram-negative bacterium that causes serious infections in aquaculture and exhibits significant multidrug resistance. The LysR-type transcriptional regulator (LTTR) family proteins are a well-known group of transcriptional regulators involved in diverse physiological functions. However, the role of LTTRs in the regulation of bacterial resistance to antibiotics is still largely unknown. In this study, to further investigate the role of four putative LTTR family proteins (A0KIU1, A0KJ82, A0KPK0, and A0KQ63) in antibiotic resistance in A. hydrophila, their genes were cloned and overexpressed in engineered Escherichia coli. After the optimization of experimental conditions including incubation time, temperature, and IPTG concentration, these proteins were successfully purified, and their specific antibodies against mice were obtained. Using western blot analysis, we found that these LTTR family proteins were downregulated in A. hydrophila following antibiotic treatment, indicating that they may be involved in the regulation of antibiotic resistance. Additionally, minimum inhibitory concentration (MIC) assays of chloramphenicol (CM), chlortetracycline (CTC), ciprofloxacin (CF), furazolidone (FZ), and balofloxacin (BF) in E. coli showed that overexpression of these LTTRs led to increased sensitivity to several antibiotics. To further validate their functional role in antibiotic resistance, we demonstrated that bacteria with loss of A0KQ63 (ΔAHA_3980) exhibited multi-drug resistance properties. Our results indicate that these LTTR family proteins may play an important role in the antibiotic resistance of A. hydrophila, and the that underlying mechanisms controlling antibiotic resistance should be further investigated.


Assuntos
Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/genética , Farmacorresistência Bacteriana , Regulação Bacteriana da Expressão Gênica , Genes Reguladores , Fatores de Transcrição/metabolismo , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Western Blotting , Clonagem Molecular , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/metabolismo , Deleção de Genes , Expressão Gênica , Perfilação da Expressão Gênica , Genes Bacterianos , Camundongos , Testes de Sensibilidade Microbiana , Fatores de Transcrição/análise , Fatores de Transcrição/genética
2.
Sheng Wu Gong Cheng Xue Bao ; 35(5): 759-765, 2019 May 25.
Artigo em Chinês | MEDLINE | ID: mdl-31222994

RESUMO

As one of the most common pathogens in aquatic animals, Aeromonas hydrophila exhibits a wide range of pathogenicity. Due to factors like unreasonable use of antibiotics and horizontal gene transfer mediated by plasmids, many resistant strains of Aeromonas hydrophila were isolated from ready-to-eat seafood products in retail markets, supermarkets and restaurants. These strains carry many resistance genes. Therefore, it is essential to explore the key control points, and seek for prevention and control strategies so as to effectively alleviate antibiotic resistance. We review here the prevalence of drug resistance of Aeromonas hydrophila in China, and its main infection and resistance mechanisms, and the main means and strategies for reducing and preventing drug resistance. We also address further research directions and focus on drug resistance in Aeromonas hydrophila of the aquatic product.


Assuntos
Aeromonas hydrophila , Antibacterianos , Farmacorresistência Bacteriana , Doenças dos Peixes , Infecções por Bactérias Gram-Negativas , Aeromonas hydrophila/efeitos dos fármacos , Animais , Antibacterianos/farmacologia , China/epidemiologia , Doenças dos Peixes/epidemiologia , Doenças dos Peixes/microbiologia , Pesqueiros , Peixes , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Pesquisa
3.
Ecotoxicol Environ Saf ; 180: 309-316, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31102840

RESUMO

Triclosan (TCS) is a biocide commonly used in household and personal care items to prevent the microbial growth and is currently considered as an emerging pollutant. It has a ubiquitous distribution which can substantially contribute towards antimicrobial resistance. The present study was designed to evaluate the effect of different concentrations of TCS exposure on the antibiotic sensitivity of aquatic bacteria. Aeromonas hydrophila ATCC® 49140™ and Edwardsiella tarda ATCC® 15947™ exposed to TCS for short (30 min) and long duration (serial passages). The agar-disc diffusion assay during the serial passages of TCS exposure and subsequent exposure withdrawal showed clinically insignificant changes in the zone of inhibition for six selected antibiotics in both bacterial strains at all exposure concentrations. Four folds concentration-dependent increase in the minimum inhibitory concentrations (MICs) of TCS was observed in both the strains following TCS exposure. Similarly, a concentration-dependent increase in the MICs of oxytetracycline (OTC) up to 4 folds in A. hydrophila, and up to 8 folds in E. tarda, was also documented during the TCS exposure. In all the cases, withdrawal of TCS exposure effectively reduced the MICs of TCS and OTC in blank passages suggesting a decline in acquired resistance. The frequencies of mutation during 30 min TCS exposure for E. tarda and A. hydrophila ranged between >10-6 and 10-7 levels. Nevertheless, the TCS exposure did not cause any detectable mutation on the fabV gene of A. hydrophila indicating that the TCS may elicit phenotypic adaptation or other resistance mechanism. Although the reduction in MICs due to exposure withdrawal did not restore the bacterial susceptibility up to the initial level, the study proved that the reduced TCS use could significantly help reduce the antimicrobial-resistance and cross-resistance in pathogenic bacteria.


Assuntos
Aeromonas hydrophila/efeitos dos fármacos , Antibacterianos/farmacologia , Desinfetantes/toxicidade , Farmacorresistência Bacteriana , Edwardsiella tarda/efeitos dos fármacos , Triclosan/toxicidade , Aeromonas hydrophila/genética , Relação Dose-Resposta a Droga , Farmacorresistência Bacteriana/genética , Edwardsiella tarda/genética , Humanos , Testes de Sensibilidade Microbiana , Fatores de Tempo
4.
Fish Shellfish Immunol ; 87: 202-211, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30639479

RESUMO

The present study reveals purification and characterization of a C-type lectin from the serum of pearl spot, Etroplus suratensis (Es-Lec). The Es-Lec was purified by affinity chromatography with mannose coupled sepharose CL-4B column and it exhibits single band with a molecular weight of 75 kDa in SDS-PAGE. The surface morphology of purified Es-Lec displays the homogeneous nature of protein. A distinct peak with a retention time of 2.958 min was appeared in high performance liquid chromatography (HPLC), X-ray diffraction (XRD) analysis expresses a single peak at 31.8372̊ and MALDI-TOF peaks which shows the purity and crystalline nature of the protein respectively. Functional analysis of purified Es-Lec exhibits yeast agglutination activity against Saccharomyces cerevisiae and has the ability to agglutinate the human erythrocytes, which was observed by light microscopy and haemagglutination inhibition was also done. In addition, purified Es-Lec showed the broad spectrum of antibacterial activity against Gram negative Vibrio parahaemolyticus and Aeromonas hydrophila. Antibiofilm potential of purified Es-Lec against selected Gram-negative bacteria exhibited the disruption of biofilm architecture at the concentration of 50 µg ml-1 and also it exhibited antiviral and anticancer activity.


Assuntos
Anti-Infecciosos/farmacologia , Biofilmes/efeitos dos fármacos , Ciclídeos/fisiologia , Bactérias Gram-Negativas/efeitos dos fármacos , Lectinas Tipo C/análise , Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/fisiologia , Animais , Anti-Infecciosos/análise , Anti-Infecciosos/sangue , Cromatografia de Afinidade/veterinária , Cromatografia Líquida de Alta Pressão/veterinária , Eritrócitos/efeitos dos fármacos , Bactérias Gram-Negativas/fisiologia , Testes de Inibição da Hemaglutinação/veterinária , Humanos , Lectinas Tipo C/sangue , Microscopia/veterinária , Saccharomyces cerevisiae/efeitos dos fármacos , Vibrio parahaemolyticus/efeitos dos fármacos , Vibrio parahaemolyticus/fisiologia , Difração de Raios X/veterinária
5.
Fish Shellfish Immunol ; 87: 129-135, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30615988

RESUMO

Intelectin, a lectin discovered recently, has been identified in various vertebrate species, such as fish, amphibians, and mammals. In one of our previous studies, the efficient bacteria binding and agglutinating activity of the recombinant Megalobrama amblycephala intelectin protein (rMamINTL) and the enhanced immunopositive localization have been observed in the hepatic macrophage-like cells (kupffer cells) post Aeromonas hydrophila infection. Thus, the present study primarily focuses on the regulatory effects of rMamINTL on M. amblycephala macrophages. This study revealed a prominent LPS-binding activity of rMamINTL and a significantly increased phagocytosis of rMamINTL-treated A. hydrophila by M. amblycephala macrophages. However, the rMamINTL-treated M. amblycephala macrophages exhibited no evident regulatory effect on phagocytosis, whereas the enhanced killing activity of the rMamINTL-treated macrophages was observed, which may be attributed to the induced respiratory burst activity and the expression of inflammatory cytokines. In addition, the anti-proliferation effect of rMamINTL on two tumor cells was observed. However, its mechanism remains to be further studied. In short, these results show that MamINTL is a multifunctional immune protein with effective immunomodulatory activity.


Assuntos
Aeromonas hydrophila/efeitos dos fármacos , Cyprinidae/imunologia , Lectinas/farmacologia , Fagocitose/efeitos dos fármacos , Animais , Cyprinidae/microbiologia , Citocinas/metabolismo , Doenças dos Peixes/imunologia , Doenças dos Peixes/microbiologia , Proteínas de Peixes/metabolismo , Infecções por Bactérias Gram-Negativas/imunologia , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Imunidade Inata , Lectinas/química , Lectinas/metabolismo , Macrófagos , Explosão Respiratória
6.
Lett Appl Microbiol ; 68(3): 212-218, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30609084

RESUMO

Hundreds of farmed Siamese crocodiles (Crocodylus siamensis) died during July 2016 at a farm in Wenchang, Hainan, China. In two necropsied crocodiles, we observed symptoms of dermatorrhagia, hepatomegaly and hepatic congestion. Pulmonitis was diagnosed by pulmonary congestion and pulmonary fibrinous exudate. Septicaemia was diagnosed by isolation of three Aeromonas species from blood and visceral tissues; A. dhakensis, A. hydrophila and A. jandaei were identified by biochemical and molecular tests. We used a zebrafish model to determine the half-maximal lethal dose (LD50 ), and A. dhakensis was found to be the most virulent species, with an LD50 of 8·91 × 105 CFU per ml. The results of a drug sensitivity test indicated that these species were sensitive to 11 antibiotics. This is the first report of A. dhakensis, A. hydrophila and A. jandaei being isolated from a mixed infection in Siamese crocodiles. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, we isolated three species of Aeromonas (A. dhakensis, A. hydrophila and A. jandae) from farmed Siamese crocodiles with fatal fibrinous pneumonia and septicaemia. This is the first description of a mixed infection with three Aeromonas species among captive crocodilians.


Assuntos
Aeromonas hydrophila/classificação , Aeromonas hydrophila/isolamento & purificação , Jacarés e Crocodilos/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Pneumonia/microbiologia , Sepse/microbiologia , Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/genética , Animais , Antibacterianos/farmacologia , China , Coinfecção , DNA Girase/genética , RNA Polimerases Dirigidas por DNA/genética , Água Doce , Testes de Sensibilidade Microbiana , Fator sigma/genética , Peixe-Zebra/microbiologia
7.
J Med Microbiol ; 67(11): 1535-1537, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30289383

RESUMO

Several species of Aeromonas produce the enzyme CphA metallo-ß-lactamase. This study describes an isolate of Aeromonas hydrophila harbouring an acquired gene encoding the carbapenemase GES-24. This isolate was obtained from an inpatient in Okinawa, Japan, with no apparent record of travelling overseas. The minimum inhibitory concentrations of carbapenems against this isolate were 8 µg ml-1 for imipenem and 16 µg ml-1 for meropenem. Recombinant GES-24 hydrolyzed all of the tested ß-lactams, including imipenem and meropenem. The genomic environment surrounding blaGES-24 was intI1-blaGES-24-aac(6')-IIc-qacEdelta1-sulI-orfX-tetR-tetE. This is the first report of A. hydrophila producing a GES-type carbapenemase.


Assuntos
Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/genética , Carbapenêmicos/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Infecções por Bactérias Gram-Negativas/epidemiologia , beta-Lactamases/genética , Aeromonas hydrophila/enzimologia , Aeromonas hydrophila/isolamento & purificação , Idoso de 80 Anos ou mais , Antibacterianos/farmacologia , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/efeitos dos fármacos , Bile/microbiologia , DNA Bacteriano/genética , Feminino , Genes Bacterianos , Genoma Bacteriano , Infecções por Bactérias Gram-Negativas/microbiologia , Hospitalização , Humanos , Japão/epidemiologia , Testes de Sensibilidade Microbiana , Análise de Sequência de DNA , beta-Lactamases/biossíntese , beta-Lactamases/efeitos dos fármacos
8.
Mar Drugs ; 16(6)2018 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-29874792

RESUMO

We report on the isolation and characterization of an acid- and bile-tolerant bacterial strain, Bacillus sp. YB1701 with antibacterial and quorum-quenching activity. Strain YB1701 was isolated from coastal sediment samples and characterized by biochemical tests and 16S rRNA sequencing. In vitro study indicated that strain YB1701 can survive at pH 2.0 for up to 3 h and tolerate bile up to 2.0% concentration even after 12 h of exposure. Strain YB1701 showed antimicrobial activity against fish pathogens Aeromonas hydrophila and Vibrio parahemolyticus using an agar well diffusion assay. The trial test showed dietary supplementation of YB1701 significantly improved the resistance of Carassius auratus gibelio against A. hydrophila challenge. The safety assessment revealed that the isolate Bacillus sp. YB1701 was not cytotoxic to Carassius auratus gibelio or mice and did not exhibit hemolytic activity on rabbit blood agar plate. Disc-diffusion assays using a panel of antibiotics listed by the European Food Safety Authority (EFSA) showed that YB1701 was susceptible to selected antibiotics. Under laboratory conditions, the degradation rate of organic waste (predominately fish excrement) for 14 days by YB1701 was 79.69%. Results from the present study suggest that strain YB1701 is a potential probiotic strain and can be used in aquaculture for degrading organic waste and improving disease resistance of fish against bacterial infection. Further study is needed to assess the utility of strain YB1701 on a commercial scale.


Assuntos
Antibacterianos/farmacologia , Organismos Aquáticos/química , Bacillus/química , Doenças dos Peixes/tratamento farmacológico , Probióticos/farmacologia , Aeromonas hydrophila/efeitos dos fármacos , Ração Animal , Animais , Antibacterianos/química , Aquicultura/métodos , Bactérias/efeitos dos fármacos , Infecções Bacterianas/tratamento farmacológico , Percepção de Quorum/efeitos dos fármacos , RNA Ribossômico 16S/genética , Vibrio parahaemolyticus/efeitos dos fármacos
9.
Microb Pathog ; 122: 137-143, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29885365

RESUMO

Quorum sensing (QS) is a signal sensing system by which bacteria monitor the density of their population, thus, targeting to QS system may be an alternative approach to control diverse cellular processes including the microbial contamination and the virulence of human and plant pathogens as bacteria have been evolving resistance to antibiotics. In this study, curcumin liposomes were prepared by film dispersion method to increase its bioavailability against QS systems of food-borne epathogenic bacteria, i.e. Aeromonas hydrophila and Serratia grimesii. And their physicochemical properties were measured including particle size, zeta-potential entrapment rate as well as drug-loading rate. Meanwhile, the effects of curcumin liposomes on QS phenomenon of food-borne pathogens including biofilm formation, extracellular protease, swimming motility et al. were determined. Results showed that the average diameter of curcumin liposomes was (207 ±â€¯8.2) nm and the entrapment rate and drug-loading rate were 82.71% and 23.33%. The zeta-potential of curcumin liposomes were (-37 ±â€¯1.56) mv. Curcumin liposomes showed uniform structures by scanning electron microscopy (SEM). The curcumin liposomes could significantly inhibit QS systems of the two pathogens and the biological availability of curcumin has been improved.


Assuntos
Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/fisiologia , Curcumina/metabolismo , Lipossomos/metabolismo , Percepção de Quorum/efeitos dos fármacos , Serratia/efeitos dos fármacos , Serratia/fisiologia , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Lipossomos/ultraestrutura , Locomoção/efeitos dos fármacos , Microscopia Eletrônica de Varredura , Peptídeo Hidrolases/metabolismo
10.
J Appl Microbiol ; 125(3): 655-665, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29741243

RESUMO

AIMS: This study investigated the antibacterial activity of five phytochemicals (carvacrol, citral, eugenol, linalool and thymol) alone or in combination with florfenicol or oxytetracycline against bacteria isolated from silver catfish (Rhamdia quelen). We also analysed the potential of these compounds to inhibit biofilm formation and haemolysis caused by the bacteria. METHODS AND RESULTS: Bacteria were tested with antimicrobials to calculate the multiple antibiotic resistances. The checkerboard assay was used to evaluate a putative synergy between five phytochemicals and antimicrobials against the strains isolated. The biofilm formation inhibition assay was performed with phytochemicals and antimicrobials, and the haemolysis inhibition assay was performed with the phytochemicals. Carvacrol, eugenol and thymol were the most effective phytochemicals. Three combinations (linalool with florfenicol or oxytetracycline against Aeromonas hydrophila and citral with oxytetracycline against Citrobacter freundii) demonstrated synergy in the checkerboard assay. All phytochemicals inhibited biofilm formation and haemolysis activity. CONCLUSION: The tested phytochemicals showed satisfactory activity against fish pathogenic bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: The phytochemicals did not present antagonistic interactions with the antimicrobials, allowing their combined use, which may contribute to a decrease in the use of conventional drugs and their residues in aquatic environment.


Assuntos
Antibacterianos/farmacologia , Peixes-Gato/microbiologia , Doenças dos Peixes/microbiologia , Monoterpenos/farmacologia , Compostos Fitoquímicos/farmacologia , Aeromonas hydrophila/efeitos dos fármacos , Animais , Citrobacter/efeitos dos fármacos
11.
Int J Biol Macromol ; 113: 1105-1115, 2018 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-29545064

RESUMO

Despite the potential antimicrobial and water purification benefits of chitosan-based nanocomposites, there are growing concerns regarding the hazards of leached nanoparticles (NPs) to the in-contact circumference. The antibacterial performance of the nanocomposites of chitosan with silver and copper NPs and carbon nanotubes was assessed with an emphasis on their impact on fish health. The minimal inhibitory concentrations of each preparation and the growth curves of Aeromonas hydrophila exposed to different nanocomposites were measured. Five groups of Oreochromis niloticus were exposed to chitosan nanocomposites for three weeks. A combination of a low concentration of the NPs in the chitosan matrix improved their antimicrobial properties. However, aqueous exposure to these materials still had hazardous effects on fish health. Experimental groups of O. niloticus exposed to these nanocomposites exhibited oxidative stress, tissue DNA fragmentation and higher expression of pro-inflammatory and immune-related genes such as TNF-α and IL1ß. Various pathological tissue alterations were observed in gills, liver, spleen and intestine. Exposure to some of the prepared nanocomposites led to significant DNA damage in hepatic cells with a marked increase in the apoptotic index.


Assuntos
Anti-Infecciosos/química , Organismos Aquáticos/efeitos dos fármacos , Quitosana/química , Cobre/química , Nanocompostos/química , Nanotubos de Carbono/química , Prata/química , Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/crescimento & desenvolvimento , Animais , Anti-Infecciosos/farmacologia , Anti-Infecciosos/toxicidade , Ciclídeos/metabolismo , Citocinas/metabolismo , Relação Dose-Resposta a Droga , Ecotoxicologia , Regulação da Expressão Gênica/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Estresse Oxidativo/efeitos dos fármacos , Medição de Risco
12.
J Chem Ecol ; 44(3): 312-325, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29427191

RESUMO

Most amphibians produce their own defensive chemicals; however, poison frogs sequester their alkaloid-based defenses from dietary arthropods. Alkaloids function as a defense against predators, and certain types appear to inhibit microbial growth. Alkaloid defenses vary considerably among populations of poison frogs, reflecting geographic differences in availability of dietary arthropods. Consequently, environmentally driven differences in frog defenses may have significant implications regarding their protection against pathogens. While natural alkaloid mixtures in dendrobatid poison frogs have recently been shown to inhibit growth of non-pathogenic microbes, no studies have examined the effectiveness of alkaloids against microbes that infect these frogs. Herein, we examined how alkaloid defenses in the dendrobatid poison frog, Oophaga pumilio, affect growth of the known anuran pathogens Aeromonas hydrophila and Klebsiella pneumoniae. Frogs were collected from five locations throughout Costa Rica that are known to vary in their alkaloid profiles. Alkaloids were isolated from individual skins, and extracts were assayed against both pathogens. Microbe subcultures were inoculated with extracted alkaloids to create dose-response curves. Subsequent spectrophotometry and cell counting assays were used to assess growth inhibition. GC-MS was used to characterize and quantify alkaloids in frog extracts, and our results suggest that variation in alkaloid defenses lead to differences in inhibition of these pathogens. The present study provides the first evidence that alkaloid variation in a dendrobatid poison frog is associated with differences in inhibition of anuran pathogens, and offers further support that alkaloid defenses in poison frogs confer protection against both pathogens and predators.


Assuntos
Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/fisiologia , Alcaloides/metabolismo , Anuros/metabolismo , Anuros/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/fisiologia , Aeromonas hydrophila/crescimento & desenvolvimento , Alcaloides/farmacologia , Animais , Relação Dose-Resposta a Droga , Klebsiella pneumoniae/crescimento & desenvolvimento
13.
J Appl Microbiol ; 124(6): 1629-1637, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29453863

RESUMO

AIMS: Aeromonas hydrophila has been isolated from various fish species in Egypt and is known to carry virulence and antimicrobial resistance genes, which pose a risk for public health. The aim of the present study is to report, for the first time, the infection of mullet (Mugil cephalus) with A. hydrophila and to clarify the potential association between antimicrobial resistance and virulence traits encoded in A. hydrophila. METHODS AND RESULTS: In this study, the occurrence of A. hydrophila in marketed mullet and the antimicrobial resistance phenotypes of these isolates were determined. Aeromonas hydrophila isolates were screened for the presence of virulence and ß-lactam resistance genes; the correlation between both gene groups was also investigated. The infection rate of examined mullet with A. hydrophila was 37% (50/135). The highest antimicrobial resistance was detected to cefoxitin (100%), followed by ampicillin (84%), ceftazidime (56%) and cefotaxime (40%). Only 4% of the isolates were resistant to erythromycin; 6% were resistant to both gentamicin and kanamycin with no resistance to ciprofloxacin. Variable frequencies of virulence and ß-lactam resistance genes were evident from PCR, where aerA and blaTEM predominated. The study also indicated a general weak positive correlation (R = 0·3) between both virulence and ß-lactam resistance genes. Some of the studied virulence genes (e.g. aerA:hlyA and hlyA:ast) were found to correlate positively. CONCLUSIONS: The presence of virulence and resistance genes in A. hydrophila from food sources poses a serious threat to public health. To our knowledge, this is the first report describing the occurrence of A. hydrophila in mullet and highlighting the coexistence of virulence and ß-lactam resistance genes encoded by these bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: These data provide insights into the potential association of antimicrobial resistance and virulence genes in A. hydrophila from marketed mullet in Egypt, which could pose threats to humans even if a weak positive correlation exists between both genes.


Assuntos
Aeromonas hydrophila , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Smegmamorpha/microbiologia , Resistência beta-Lactâmica/genética , Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/genética , Aeromonas hydrophila/patogenicidade , Animais , Antibacterianos/farmacologia , Egito , Genes Bacterianos/genética , Reação em Cadeia da Polimerase , Virulência/genética
14.
J Vet Med Sci ; 80(3): 421-426, 2018 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-29367518

RESUMO

Aeromonas hydrophila is an opportunistic pathogen of a variety of aquatic animals that displays extreme diversity in drug resistance, phenotypes, virulence genes, and virulence. In this study, eight pathogenic A. hydrophila strains were isolated from diseased Amur sturgeons and investigated for their sensitivity to select antibiotics, their phenotype, virulence genes, and virulence. According to the phylogenetic analysis of the DNA gyrase subunit B protein, the eight isolates formed a single branch in the A. hydrophila group. The antibiotics ceftazidime, cefuroxime, cefoperazone, cefotaxime, ceftriaxone, aztreonam, and cefepime appeared effective against them. All of the isolates possessed the virulence genes for aerolysin, flagellin, heat-stable cytotonic enterotoxin, heat-labile cytotonic enterotoxin, hemolysin, and elastase, while only one isolate, HZ8, possessed the gene for lateral flagella. The cytolytic enterotoxin and lipase genes were present in all isolates, except in ZJ10 and ZJ12. Enterobacterial repetitive intergenic consensus sequence PCR indicated that the eight A. hydrophila isolates could be divided into four types. Isolates YW2, TR3, HZ8 and ZJ10, each representing a different type, were selected for challenge experiments. The challenge tests revealed that isolate HZ8 had the lowest lethal dose, causing 50% mortality at 2.30 × 104 colony forming units (cfu)/ml. The isolate ZJ10 had the highest LD50, 1.25 × 106 cfu/ml. Knowledge of the characteristics of the A. hydrophila isolates obtained from Amur sturgeon will be beneficial in developing potential disease control strategies.


Assuntos
Aeromonas hydrophila/patogenicidade , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/genética , Aeromonas hydrophila/isolamento & purificação , Animais , Antibacterianos/farmacologia , Peixes/microbiologia , Genes Bacterianos/genética , Infecções por Bactérias Gram-Negativas/microbiologia , Testes de Sensibilidade Microbiana/veterinária , Filogenia , Virulência
15.
F1000Res ; 7: 1847, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30984371

RESUMO

Background: This study aims to describe the antibacterial and immunostimulant abilities of Boesenbergia pandurata (BP), Solanum ferox (SF) and Zingiber Zerumbet (ZZ) plant extracts to treat and prevent Aeromonas hydrophila and Pseudomonas fluorescens infection on Tilapia ( Oreochromis niloticus). Methods: Tilapia (initial weight 15±2 g) were injected intramuscularly (0.1 ml/fish) with a combination of A. hydrophila and P. fluorescens at a density of 1×10 5 CFU ml -1 of each bacteria. Treatment trials were performed at day 7 post-injection with each combined extract, while the prevention trial was performed by including the combined extract into the diet for six and seven days prior to injection. Various combinations of extract-60 ml SF extract/kg feed with 40 ml ZZ/kg feed (SF60/ZZ40), SF50/ZZ50, BP90/SF10, and BP50/SF50-were mixed with a commercial diet and used in both treatment and prevention trials. Haematological and immunological parameters were performed every week for four weeks. Results: In prevention trials, tilapia fed SF50/ZZ50 showed a significant increase of white and red blood cells from weeks 2 to 4. Similarly, significantly increased haematocrit was also found in tilapia fed SF50/ZZ50 in the treatment trial but not in the prevention trial. However, haemoglobin of tilapia in both trials was not affected by any of the various combinations of extract in the diet. Furthermore, phagocytic, respiratory burst, lysozyme activity indexes and survival rate of fish fed with combined extracts were found to be significantly higher than controls. Moreover, the amount of pathogenic bacteria in fish that were fed combined extracts was also lower than the control and was significantly different at week 4. Conclusions: This study indicates that the addition of combined extract into feed has a positive effect on the tilapia's immune system. The SF50/ZZ50 combination appears to improve the innate immune system of tilapia to treat and prevent bacterial infections.


Assuntos
Aeromonas hydrophila/fisiologia , Ciclídeos/microbiologia , Doenças dos Peixes/tratamento farmacológico , Doenças dos Peixes/microbiologia , Extratos Vegetais/uso terapêutico , Pseudomonas fluorescens/fisiologia , Aeromonas hydrophila/efeitos dos fármacos , Animais , Bornéu , Doenças dos Peixes/sangue , Muramidase/metabolismo , Fagocitose/efeitos dos fármacos , Extratos Vegetais/farmacologia , Pseudomonas fluorescens/efeitos dos fármacos , Explosão Respiratória/efeitos dos fármacos , Análise de Sobrevida
16.
Vet Microbiol ; 211: 119-123, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29102106

RESUMO

Aeromonas hydrophila is a common zoonotic pathogen which can cause several infections both in human and animals, particular aquatic animals. Antibiotics have been widely used in the treatment of A. hydrophila infections, however, the development of resistance has limited the treatment for these infections. There is an urgent need for novel agents and strategies against these infections. Aerolysin, a pore-forming toxin secreted by most pathogenic A. hydrophila, is known to contribute to the pathogenesis of A. hydrophila infections. Therefore, aerolysin has been identified as a potential target for drug discovery. In this paper, we found that magnolol, a natural compound without anti -A. hydrophila activity, could significantly inhibit the hemolytic activity of A. hydrophila culture supernatants by inhibiting the transcription of the aerolysin encoding gene aerA at low concentrations. Furthermore, the survival assay showed that magnolol could significantly reduce the mortality induced by A. hydrophila infection in channel catfish (Ictalurus punctatus). Taken together, these findings provide a potent agent against A. hydrophila infections.


Assuntos
Aeromonas hydrophila/efeitos dos fármacos , Toxinas Bacterianas/antagonistas & inibidores , Compostos de Bifenilo/farmacologia , Doenças dos Peixes/prevenção & controle , Infecções por Bactérias Gram-Negativas/veterinária , Lignanas/farmacologia , Proteínas Citotóxicas Formadoras de Poros/antagonistas & inibidores , Aeromonas hydrophila/patogenicidade , Animais , Compostos de Bifenilo/química , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/prevenção & controle , Hemólise/efeitos dos fármacos , Ictaluridae , Lignanas/química , Testes de Sensibilidade Microbiana/veterinária , Fatores de Virulência
17.
An Acad Bras Cienc ; 89(3): 1785-1799, 2017 Jul-Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28767889

RESUMO

The effect of the ethanolic extract of propolis (EEP) on Aeromonas hydrophila was analyzed by determination of minimum inhibitory concentration (MIC). Then, the effects of crude propolis powder (CPP) on growth, hemato-immune parameters of the Nile tilapia, as well as its effects on resistance to A. hydrophila challenge were investigated. The CPP (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0%) was added to the diet of 280 Nile tilapia (50.0 ± 5.7 g fish-1). Hemato-immune parameters were analyzed before and after the bacterial challenge. Red blood cell, hematocrit, hemoglobin, mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), and hydrogen peroxide (H2O2) and nitric oxide (NO) were evaluated. The MIC of the EEP was 13% (v/v) with a bactericidal effect after 24 hours. Growth performance was significantly lower for those fish fed diets containing 2.5 and 3% of CPP compared to the control diet. Differences in CPP levels affected fish hemoglobin, neutrophils number and NO following the bacterial challenge. For others parameters no significant differences were observed. Our results show that although propolis has bactericidal properties in vitro, the addition of crude propolis powder to Nile tilapia extruded diets does not necessarily lead to an improvement of fish health.


Assuntos
Aeromonas hydrophila/efeitos dos fármacos , Ciclídeos/microbiologia , Doenças dos Peixes/dietoterapia , Infecções por Bactérias Gram-Negativas/veterinária , Própole/administração & dosagem , Animais , Ciclídeos/sangue , Suplementos Nutricionais , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/dietoterapia , Infecções por Bactérias Gram-Negativas/microbiologia , Imunidade Inata , Testes de Sensibilidade Microbiana , Própole/uso terapêutico
18.
Biofouling ; 33(7): 580-590, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28685594

RESUMO

The quorum sensing (QS) phenomenon regulates a myriad of pathogenic traits in the biofilm forming fish pathogen, Aeromonas hydrophila. Blocking the QS mechanism of A. hydrophila is a novel strategy to prevent disease in fish. This study evaluated the effect of tannic acid, a QS inhibitor, on A. hydrophila-associated QS regulated phenomena. A streaking assay with Chromobacterium violaceum (CVO26) reported the presence of N-acyl homoserine lactone (AHL) in A. hydrophila, which was confirmed by HPLC and GC-MS analysis. Tannic acid-treated A. hydrophila showed a considerable reduction in violacein production, blood haemolysis activity and the pattern of swarming motility. Biofilm formation was significantly reduced (p < 0.001) (up to 95%), after tannic acid treatment for 48 h. Analysis by qRT-PCR revealed significant downregulation (p < 0.001) of AhyI and AhyR transcripts in A. hydrophila after tannic acid treatment. Co-stimulation of Catla catla with A. hydrophila and tannic acid attenuated pathogen-induced skin haemorrhages and increased the relative survival rate up to 86.6%. The study provides a mechanistic basis of tannic acid as a QS blocker and indicates its therapeutic potential against A. hydrophila-induced pathogenesis.


Assuntos
Aeromonas hydrophila/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Cyprinidae/microbiologia , Percepção de Quorum/efeitos dos fármacos , Taninos/farmacologia , 4-Butirolactona/análogos & derivados , 4-Butirolactona/metabolismo , Aeromonas hydrophila/genética , Aeromonas hydrophila/patogenicidade , Aeromonas hydrophila/fisiologia , Animais , Proteínas de Bactérias/genética , Chromobacterium/fisiologia , Relação Dose-Resposta a Droga , Regulação para Baixo , Virulência/efeitos dos fármacos
19.
J Gen Appl Microbiol ; 63(4): 246-253, 2017 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-28747586

RESUMO

The use of probiotic bacteria to control bacterial infection in farmed fish is of clear practical interest. The aims of this study were to isolate and select a probiotic Bacillus sp. and to evaluate the effects of its supplementation on the growth and disease resistance of hybrid catfish. Bacillus siamensis strain B44v, selectively isolated from Thai pickled vegetables (Phak-dong), displayed a high potential as a probiotic in catfish culture. This bacterium produced a bacteriocin-like substance and exhibited a broad-spectrum antibacterial activity inhibiting both Gram-positive and Gram-negative bacteria, especially the fish pathogens Aeromonas hydrophila and Streptococcus agalactiae. The susceptibility to all 14 antibiotics tested implies its less possibility to be the antibiotic-resistant bacterium. Bacillus siamensis strain B44v possessed interesting adhesion properties, as shown by its high percentages of hydrophobicity (64.8%), auto-agglutination (73.8%), co-aggregation (67.2% with A. hydrophila FW52 and 63.5% with S. agalactiae F3S), and mucin binding (88.7%). The strain B44v survived simulated gastrointestinal conditions and produced protease and cellulase enzymes. Hybrid catfish (C. macrocephalus × C. gariepinus) were employed in the feed-trial experiments. Fish fed diet containing strain B44v (107 CFU/g feed) displayed not only no mortality but also growth improvement. At the end of the feed trial, fish were challenged by an intraperitoneal injection of Aeromonas hydrophila FW52. The Bacillus siamensis strain B44v fed fish survived (75.0%; p < 0.05) better than the controls (36.7%; p < 0.05) after a two week challenge. These collective results present for the first time the potential of Bacillus siamensis strain B44v for use as a bacterial probiotic in aquaculture.


Assuntos
Ração Animal , Aquicultura/métodos , Bacillus , Suplementos Nutricionais , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Probióticos , Aeromonas hydrophila/efeitos dos fármacos , Animais , Antibacterianos/farmacologia , Bacillus/química , Bacillus/efeitos dos fármacos , Bacillus/isolamento & purificação , Peixes-Gato/crescimento & desenvolvimento , Peixes-Gato/microbiologia , Resistência à Doença , Doenças dos Peixes/mortalidade , Doenças dos Peixes/prevenção & controle , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/mortalidade , Infecções por Bactérias Gram-Negativas/prevenção & controle , Probióticos/administração & dosagem , Probióticos/isolamento & purificação , Streptococcus agalactiae/efeitos dos fármacos , Tailândia , Produtos Vegetais/microbiologia
20.
PLoS One ; 12(7): e0179549, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28708867

RESUMO

Enrofloxacin is the most commonly used antibiotic to control diseases in aquatic animals caused by A. hydrophila. This study conducted de novo transcriptome sequencing and compared the global transcriptomes of enrofloxacin-resistant and enrofloxacin-susceptible strains. We got a total of 4,714 unigenes were assembled. Of these, 4,122 were annotated. A total of 3,280 unigenes were assigned to GO, 3,388 unigenes were classified into Cluster of Orthologous Groups of proteins (COG) using BLAST and BLAST2GO software, and 2,568 were mapped onto pathways using the Kyoto Encyclopedia of Gene and Genomes Pathway database. Furthermore, 218 unigenes were deemed to be DEGs. After enrofloxacin treatment, 135 genes were upregulated and 83 genes were downregulated. The GO terms biological process (126 genes) and metabolic process (136 genes) were the most enriched, and the terms for protein folding, response to stress, and SOS response were also significantly enriched. This study identified enrofloxacin treatment affects multiple biological functions of A. hydrophila. Enrofloxacin resistance in A. hydrophila is closely related to the reduction of intracellular drug accumulation caused by ABC transporters and increased expression of topoisomerase IV.


Assuntos
Aeromonas hydrophila/genética , Farmacorresistência Bacteriana/genética , Fluoroquinolonas/farmacologia , Transcriptoma/efeitos dos fármacos , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Aeromonas hydrophila/efeitos dos fármacos , Aeromonas hydrophila/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Análise por Conglomerados , DNA Topoisomerase IV/genética , DNA Topoisomerase IV/metabolismo , Bases de Dados Genéticas , Regulação para Baixo/efeitos dos fármacos , Enrofloxacina , Sequenciamento de Nucleotídeos em Larga Escala , RNA Bacteriano/química , RNA Bacteriano/isolamento & purificação , RNA Bacteriano/metabolismo , Análise de Sequência de RNA , Regulação para Cima/efeitos dos fármacos
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