Sequencing and multiple antimicrobial resistance of Pseudomonas fluorescens isolated from Nile tilapia fish in Egypt / Sequenciamento e resistência antimicrobiana múltipla de Pseudomonas fluorescens isoladas de tilápia-do-nilo no Egito

Pseudomonas fluorescens is one of the main causes of septicemic diseases among freshwater fish, causing severe economic losses and decreasing farm efficiency. Thus, this research was aimed to investigate the occurrence of P. fluorescens in Nile Tilapia (O. niloticus) fish in Egypt, gene sequencing of 16SrDNA gene, and antimicrobial susceptibility. P. fluorescens strains were detected in 32% (128/400) of apparently healthy (9%; 36/400) and diseased (23%; 92/400) Nile tilapia fish. The highest prevalence was observed in gills of fish, 31.3% followed by intestine 26.9%, liver 24.2%, and kidneys 17.6%. The PCR results for the 16SrDNA gene of P. fluorescens showed 16SrDNA gene in 30% of examined isolates. Moreover, Homogeny and a strong relationship between strains of P. fluorescens was confirmed using 16SrDNA sequences. Beside the responsibility of 16SrDNA gene on the virulence of P. fluorescens. The results of antimicrobial susceptibility tests revealed that all strains were resistant to piperacillin (100%), followed by ceftazidime (29.7%), and cefepime (25.8%). The strains of P. fluorescence were highly sensitive to cefotaxime (74.2%), followed by ceftriaxone and levofloxacin (70.3% each). Interestingly, 29.7% of strains of P. fluorescens were multiple antimicrobial-resistant (MAR).

Pseudomonas fluorescens é uma das principais causas de doenças septicêmicas em peixes de água doce, causando graves perdas econômicas e diminuindo a eficiência da fazenda. Assim, esta pesquisa teve como objetivo investigar a ocorrência de P. fluorescens em peixes de tilápia-do-nilo (O. niloticus) no Egito, sequenciamento do gene 16S rDNA e suscetibilidade antimicrobiana. Cepas de P. fluorescens foram detectadas em 32% (128/400) de peixes tilápia-do-nilo aparentemente saudáveis ​​(9%; 36/400) e doentes (23%; 92/400). A maior prevalência foi observada nas brânquias dos peixes, 31,3%, seguida pelo intestino 26,9%, fígado 24,2% e rins 17,6%. Os resultados da PCR para o gene 16SrDNA de P. fluorescens mostraram o gene 16SrDNA em 30% dos isolados examinados. Além disso, a homogeneidade e uma forte relação entre cepas de P. fluorescens foi confirmada usando sequências de 16SrDNA. Além da responsabilidade do gene 16SrDNA na virulência de P. fluorescens. Os resultados dos testes de suscetibilidade antimicrobiana revelaram que todas as cepas foram resistentes à piperacilina (100%), seguida pela ceftazidima (29,7%) e cefepima (25,8%). As cepas de P. fluorescens foram altamente sensíveis à cefotaxima (74,2%), seguida pela ceftriaxona e levofloxacina (70,3% cada). Curiosamente, 29,7% das cepas de P. fluorescens eram multirresistentes a antimicrobianos (MAR).

Sequencing and multiple antimicrobial resistance of Pseudomonas fluorescens isolated from Nile tilapia fish in Egypt

Abstract Pseudomonas fluorescens is one of the main causes of septicemic diseases among freshwater fish, causing severe economic losses and decreasing farm efficiency. Thus, this research was aimed to investigate the occurrence of P. fluorescens in Nile Tilapia (O. niloticus) fish in Egypt, gene sequencing of 16SrDNA gene, and antimicrobial susceptibility. P. fluorescens strains were detected in 32% (128/400) of apparently healthy (9%; 36/400) and diseased (23%; 92/400) Nile tilapia fish. The highest prevalence was observed in gills of fish, 31.3% followed by intestine 26.9%, liver 24.2%, and kidneys 17.6%. The PCR results for the 16SrDNA gene of P. fluorescens showed 16SrDNA gene in 30% of examined isolates. Moreover, Homogeny and a strong relationship between strains of P. fluorescens was confirmed using 16SrDNA sequences. Beside the responsibility of 16SrDNA gene on the virulence of P. fluorescens. The results of antimicrobial susceptibility tests revealed that all strains were resistant to piperacillin (100%), followed by ceftazidime (29.7%), and cefepime (25.8%). The strains of P. fluorescence were highly sensitive to cefotaxime (74.2%), followed by ceftriaxone and levofloxacin (70.3% each). Interestingly, 29.7% of strains of P. fluorescens were multiple antimicrobial-resistant (MAR).

Resumo Pseudomonas fluorescens é uma das principais causas de doenças septicêmicas em peixes de água doce, causando graves perdas econômicas e diminuindo a eficiência da fazenda. Assim, esta pesquisa teve como objetivo investigar a ocorrência de P. fluorescens em peixes de tilápia-do-nilo (O. niloticus) no Egito, sequenciamento do gene 16S rDNA e suscetibilidade antimicrobiana. Cepas de P. fluorescens foram detectadas em 32% (128/400) de peixes tilápia-do-nilo aparentemente saudáveis (9%; 36/400) e doentes (23%; 92/400). A maior prevalência foi observada nas brânquias dos peixes, 31,3%, seguida pelo intestino 26,9%, fígado 24,2% e rins 17,6%. Os resultados da PCR para o gene 16SrDNA de P. fluorescens mostraram o gene 16SrDNA em 30% dos isolados examinados. Além disso, a homogeneidade e uma forte relação entre cepas de P. fluorescens foi confirmada usando sequências de 16SrDNA. Além da responsabilidade do gene 16SrDNA na virulência de P. fluorescens. Os resultados dos testes de suscetibilidade antimicrobiana revelaram que todas as cepas foram resistentes à piperacilina (100%), seguida pela ceftazidima (29,7%) e cefepima (25,8%). As cepas de P. fluorescens foram altamente sensíveis à cefotaxima (74,2%), seguida pela ceftriaxona e levofloxacina (70,3% cada). Curiosamente, 29,7% das cepas de P. fluorescens eram multirresistentes a antimicrobianos (MAR).

Beta-lactamase and integron-associated antibiotic resistance genes of Klebsiella pneumoniae isolated from Tilapia fishes (Oreochromis niloticus)

Tilapia fishes (Oreochromis niloticus) are commonly consumed and exported in Thailand. Bacterial isolation anddrug resistance from farmed tilapia fished in Thailand were previously reported. This study was purposed to studyon the distribution of human pathogenic bacteria in tilapia fishes, which were collected from Thai farms (n = 180)and fresh markets (n = 160) by identification, antibiotic susceptibility test; and conduct to identify virulence genesby molecular technique. Pathogen isolations were collected from internal organs of fish samples for identificationand test of antibiotic susceptibility according to Clinical and Laboratory Standards Institute (CLSI) criteria. blaCTX-Mand Int1 genes detection of antibiotic resistance bacteria was performed by molecular based techniques. Klebsiellapneumoniae, Edwardsiella tarda, and coagulase-negative Staphylococci were most frequent bacteria isolated fromfarming tilapia fishes, respectively. However, Escherichia coli, coagulase-negative Staphylococci, and K. pneumoniawere frequently distributed from tilapia fishes in markets of Bangkok area. Klebsiella pneumoniae, E. coli, and Proteusmirabilis were resisted to penicillin and ampicillin. Klebsiella pneumoniae is the most important isolated bacteria dueto the distribution in tilapia fishes and positive for blaCTX-M and Int1 gene detection. However, E. coli and P. mirabiliswere lack of blaCTX-M and Int1 genes, possibly there may reserve other antibiotic resistance genes

Au@PVP Core-Shell Nanoparticles Used as Surface-Enhanced Raman Spectroscopic Substrate to Detect Malachite Green / 分析化学

The core-shell nanopaticles of Au@polyvinyl-pyrrolidone ( PVP) with uniform size and controllabe shell-thickness were prepared by hydrothermal method. The core-shell nanoparticles could be assembled to be the monolayer array on Si substrate relying on the dispersion of core-shell nanoparticles arising from PVP shell. The malachite green ( MG ) absorbed by H-bond could be detected on the array under the electromagnetic enhancement of inner-core Au nanoparticles. Under the conditions of the optimum shell-thickness of Au@PVP and the appropriate absorbed time of MG, the detection of MG could be realized in the linear range from 1 × 10-10 mol/L to 1 × 10-5 mol/L with the correlation coefficient ( R2 ) of 0. 98. The detection limit was 10-12 mol/L. This method was applied to the determination of MG in tilapia fish fillets of Xiagang market. No MG was found in this real sample. The spiked recoveries of the sample ranged from 70. 8% to 126. 0%. This method is simple and accurate, and can be used for detection of MG in the fish.

Avaliação de impactos do efluente do tratamento combinado de lixiviado de aterro de resíduos sólidos urbanos e esgoto doméstico sobre a biota aquática / Assessment of impacts of combined treatment of solid urban waste landfill leachate and sewage on aquatic biota

Foi monitorado o impacto do tratamento combinado de lixiviado e esgoto doméstico de uma estação de tratamento operando em escala piloto por processo de lodos ativados, sobre peixes do gênero Tilapia: Biomarcadores de toxicidade (concentração de metalotioneínas, atividade da acetilcolinesterase, metábolitos de HPA e presença de micronúcleos) foram utilizados na avaliação dos riscos de danos aos organismos aquáticos devido à interação com poluentes contidos nos efluentes pós-tratamento. A concentração de metalotioneínas não apresentou variação significativa entre os grupos expostos e de controle. A atividade da enzima acetilcolinesterase foi inibida em apenas um dos grupos expostos, indicando possível presença de agentes inibidores no efluente tratado. A avaliação dos metabólitos dos HPA naftaleno, pireno, benzo(a)pireno e 1-hidroxipireno sinalizou a provável presença desses compostos em ao menos um dos afluentes do tratamento combinado. As frequências de micronúcleos e outras anormalidade nucleares eritrocitárias também apontam para maior incidência de danos genotóxicos em células dos organismos expostos do que nos controles. O uso de biomarcadores mostrou-se importante para possibilitar uma avaliação de danos subletais presentes em organismos expostos à fonte de poluição estudada.

The impact on tilapia fish of combined treatment of landfill leachate and domestic sewage was monitored in a waste treatment plant that operated on a pilot scale using the activated sludge process. Biomarkers of sub-lethal toxicity were used to indicate the possibility of damage to organisms due to interaction with pollutants. The concentration of metallothioneins did not indicate the increased presence of metals in fish exposed than in control groups. Acetylcholinesterase enzyme activity was inhibited in only one of the exposed groups, indicating the possible presence of organophosphate and/or carbamate pesticides in treated effluent. The PAHs used as biomarkers (naphthalene, pyrene, benzo(a)pyrene and 1-hydroxypyrene) indicated that exposed fish had a greater absorption of PAHs than control groups of fish, indicating the likely presence of these compounds in at least one of the combined treatment effluents. The frequencies of micronuclei and other erythrocytic nuclear abnormalities also indicate greater genotoxic damage in cells of organisms exposed than in control groups. The use of biomarkers proved to be important to permit an evaluation of sub-lethal damage present in organisms exposed to the pollution source studied.

The effects of 4-nonylphenol contamination on livers of Tilapia fish (Oreochromus spilurs) in Jeddah

Alkylphenol polyethoxylates is a group of estrogenic compounds. Natural or synthetic types of these compounds react with the endocrine system by binding hormone receptors, resulting in interference with their action, which is why they are called endocrine disrupting chemicals. Among their hydrolytic products are nonylphenols (NP), which are considered pollutants of aquatic environments. The objective of this study was to evaluate the pathological alterations on liver tissue of fish exposed to these compounds for long durations, starting from beginning of life and during the period of sexual maturity. Tilapia fish were obtained from Abhur fish farms, reared in the laboratory in special basins, and divided into two groups. The first maternal group was untreated and their larvae were divided into three sub-groups: control; exposed to 15μg/L; and exposed to 30 μg/L. The second maternal group was divided into 2 sub-groups: with larvae exposed to 15μg/L; and with their larvae exposed to 30 μg/L. Larvae and mother exposed to different concentrations of NP (15 and 30 μg/L) showed an increased accumulation of NP in both livers and muscles compared to the control group due to bioaccumulation. Tissue section examinations of the treated group (15 μg NP /L) showed disruption of liver architecture, with lyses, loss of nuclei, necrosis, and fatty infiltration. The changes were more marked in tissues exposed to (30 μg NP /L). Although this pollution was not lethal, its effect may be reflected in vital activities and in the economy.