Ampicillin-resistant Bacteria Research Articles

Selection of antibiotic-resistant bacterial populations in the dairy cow gut following intramuscular ceftiofur treatment for metritis

Third-generation cephalosporins such as ceftiofur are critically important antibiotics because human pathogens with resistance to these drugs contribute to high mortality rates. These antibiotics are also frequently given to dairy cattle for treating infections, emphasizing the critical role they play in both human and veterinary medicine. To investigate the impact of intramuscular ceftiofur treatment on the concentration of resistant bacteria in the gut, we focused on cows with metritis, a common bacterial infection that frequently requires antibiotic intervention. Twelve cows with metritis (cases) were enrolled and treated with intramuscular ceftiofur for 5 d along with 12 matched healthy cows that were not given ceftiofur (controls). Fecal samples were collected weekly from cows in both the case and control groups for 4 weeks, starting before the treatment of the case group. Five fecal samples per cow were used for analysis (n = 120 samples). The abundance of Gram-negative bacteria was quantified per sample after plating on MacConkey agar, which was also used to quantify the abundance of Gram-negative bacteria with resistance to ceftiofur, ampicillin, and tetracycline. Interestingly, the case cows with metritis had a greater abundance of Gram-negative bacteria than the control cows just before treatment, but no difference in abundance was observed between groups at wk 1-4. The abundance of ceftiofur-resistant Gram-negative bacteria was also similar between the case and control cows immediately before treatment of the cases. However, a significant increase in abundance of ceftiofur-resistant Gram-negative bacteria was observed in the case cows 1-week after treatment that persisted through wk 3. Although the recovery of ampicillin- and tetracycline-resistant bacteria was similar between the 2 groups post-treatment, cases had significantly higher levels of ampicillin-resistant bacteria before treatment. Collectively, these findings demonstrate that intramuscular ceftiofur treatment can affect the abundance of cultivable Gram-negative bacteria and select for ceftiofur-resistant populations that can persist for up to 3 weeks. Judicious use practices are needed to ensure that ceftiofur and other critically important antibiotics are administered only when necessary to minimize the spread of resistance and safeguard public and animal health.

Synthesis of a tetralone derivative of ampicillin to control ampicillin-resistant Staphylococcusaureus

Due to the rapid emergence of antibiotic resistant new bacterial strains and new infections, there is an urgent need for novel or newly modified and efficient alternatives of treatment. However, conventional antibiotics are still used in therapeutic settings but their efficacy is uncertain due to the rapid evolution of drug resistance. In the present study, we have synthesized a new derivative of conventional antibiotic ampicillin using SN2-type substitution reaction. NMR and mass analysis of the newly synthesized derivative of ampicillin confirmed it as ampicillin-bromo-methoxy-tetralone (ABMT). Importantly, ABMT is revealed to have efficient activity against Staphylococcus aureus (S. aureus) with a MIC value of 32 μg ml−1 while ampicillin was not effective, even at 64 μg ml−1 of concentration. Electron microscopy results confirmed the membrane-specific killing of S. aureus at 1 h of treatment. Additionally, molecular docking analysis revealed a strong binding affinity of ABMT with β-lactamase via the formation of a closed compact bridge. Our findings, avail a new derivative of ampicillin that could be a potential alternative to fight ampicillin-resistant bacteria possibly by neutralizing the β-lactamase action.

Incidence of co-resistance to antibiotics and chlorine in bacterial biofilm of hospital water systems: Insights into the risk of nosocomial infections

The presence of biofilms in drinking water distribution systems (DWDS) in healthcare settings poses a considerable risk to the biological security of water, particularly when the biofilm bacteria demonstrate antimicrobial resistance characteristics. This study aimed to investigate the occurrence of antibiotic-resistant bacteria (ARB) in biofilms within DWDS of hospitals. The chlorine resistance of the isolated ARB was analyzed, and then chlorine-resistant bacteria (CRB) were identified using molecular methods. Additionally, the presence of several antibiotic resistance genes (ARGs) was monitored in the isolated ARB. Out of the 41 biofilm samples collected from hospitals, ARB were detected in 32 (78%) of the samples. A total of 109 colonies of ARB were isolated from DWDS of hospitals, with β-lactam resistant bacteria, including ceftazidime-resistant and ampicillin-resistant bacteria, being the most frequently isolated ARB. Analyzing of ARGs revealed the highest detection of aac6, followed by sul1 gene. However, the β-lactamase genes blaCTX-M and blaTEM were not identified in the ARB, suggesting the presence of other β-lactamase genes not included in the tested panel. Exposure of ARB to free chlorine at a concentration of 0.5 mg/l showed that 64% of the isolates were CRB. However, increasing the chlorine concentration to 4 mg/l decreased the high fraction of ARB (91%). The domi‌‌nant CRB identified were Sphingomonas, Brevundimonas, Stenotrophomonas, Bacillus and Staphylococcus with Bacillus exhibiting the highest frequency. The results highlight the potential risk of biofilm formation in the DWDS of hospitals, leading to the dissemination of ARB in hospital environments, which is a great concern for the health of hospitalized patients, especially vulnerable individuals. Surveillance of antimicrobial resistance in DWDS of hospitals can provide valuable insights for shaping antimicrobial use policies and practices that ensure their efficacy.

Metabolic phenotyping of acquired ampicillin resistance using microbial volatiles from Escherichia coli cultures.

This study sought to assess the volatile organic compound (VOC) profiles of ampicillin-resistant and -susceptible Escherichia coli to evaluate whether VOC analysis may be utilized to identify resistant phenotypes. An E. coli BL21 (DE3) strain and its pET16b plasmid transformed ampicillin-resistant counterpart were cultured for 6h in drug-free, low- and high-concentrations of ampicillin. Headspace analysis was undertaken using thermal desorption-gas chromatography-mass spectrometry. Results revealed distinct VOC profiles with ampicillin-resistant bacteria distinguishable from their susceptible counterparts using as few as six compounds. A minimum of 30 compounds (fold change >2, p ≤ 0.05) were differentially expressed between the strains across all set-ups. Furthermore, three compounds (indole, acetoin and 3-methyl-1-butanol) were observed to be significantly more abundant (fold change >2, p ≤ 0.05) in the resistant strain compared to the susceptible strain both in the presence and in the absence of drug stress. Results indicate that E. coli with acquired ampicillin resistance exhibit an altered VOC profile compared to their susceptible counterpart both in the presence and in the absence of antibiotic stress. This suggests that there are fundamental differences between the metabolisms of ampicillin-resistant and -susceptible E. coli which may be detected by means of VOC analysis. Our findings suggest that VOC profiles may be utilized to differentiate between resistant and susceptible bacteria using just six compounds. Consequently, the development of machine-learning models using VOC signatures shows considerable diagnostic applicability for the rapid and accurate detection of antimicrobial resistance.

Antimicrobial Resistance of Heterotrophic Bacteria in Drinking Water-Associated Biofilms

Antimicrobial resistance (AMR) is one of the major threats to human health and is becoming an environmental challenge for water resources too. Our study’s aim was: to assess the AMR of heterotrophic bacteria in drinking water-associated biofilms against six clinically important antibiotics; to compare the prevalence of antibiotic resistant bacteria (ARB) in drinking water and in the associated biofilms; to estimate biofilm formation ability of selected isolates. Culture-dependent methods were used in the population-based study of the biofilms and in assessment of the single-species biofilm formation ability and the AMR phenotype of the isolated strains. The population proportion of the bacteria resistant to each tested antibiotic significantly differed in the biofilms formed in drinking water from different sampling points. In all biofilms, the abundance of tetracycline- and ampicillin-resistant bacteria was low, and of streptomycin-resistant bacteria was high. An increased proportion of the bacteria resistant to ciprofloxacin, chloramphenicol and streptomycin was detected in the biofilms compared to those found in the drinking water. The prevalence of ARB in the biofilms implies an impact on the drinking water quality and an assessment of the attached and the planktonic bacteria is needed to clarify the prevalence of AMR in the drinking water distribution system.

Concentrations, Size Distribution, and Community Structure Characteristics of Culturable Airborne Antibiotic-Resistant Bacteria in Xinxiang, Central China

Antimicrobial resistance is considered an important threat to global health and has recently attracted significant attention from the public. In this study, the concentrations and size distribution characteristics of culturable airborne total bacteria (TB) and four antibiotic-resistant bacteria (tetracycline-resistant bacteria (TRB), ciprofloxacin-resistant bacteria (CRB), erythromycin-resistant bacteria (ERB), and ampicillin-resistant bacteria (ARB)) were investigated for approximately one year to explore their variations under different seasons, diurnal periods, and air quality levels. The concentrations of TB and four antibiotic-resistant bacteria in winter and night were higher than during other seasons and diurnal periods. Their maximum concentrations were detected from air under moderate pollution or heavy pollution. PM2.5, PM10, SO2, and NO2 were positively related to TB and four antibiotic-resistant bacteria (p < 0.01), whereas O3 and wind speed were negatively related to them (p < 0.05). The particle size of TB and four antibiotic-resistant bacteria were mainly distributed in stage V (1.1–2.2 µm). Bacillus was the dominant genus of ARB (75.97%) and CRB (25.67%). Staphylococcus and Macrococcus were the dominant genera of TRB (46.05%) and ERB (47.67%), respectively. The opportunistic pathogens of Micrococcus, Sphingomonas, Enterococcus, Rhodococcus, and Stenotrophomonas were also identified. This study provides important references for understanding the threat of bioaerosols to human health.

Beta-lactam resistance development during the treatment processes of municipal wastewater treatment plants

This work monitored the effect of a municipal and a village wastewater treatment plant (WWTP) technology on the fate of beta-lactam resistance genes in bacterial populations in different phases of the wastewater treatment process. In case of the municipal WWTP1, the bacteria possessing a high ampicillin resistance (minimal inhibitory concentration (MIC) values of 20 mg/mL) accumulated in the sedimentation tank, which was accompanied with a higher concentration of ampicillin in the wastewater samples (28.09 ng/L) and an increase in the relative abundance of the blaTEM gene in the bacterial population. However, an opposite trend was revealed with the blaNDM-1 gene, making the sedimentation processes of WWTP1 crucial only for the accumulation of the blaTEM gene. Similarly, the comparison with the WWTP2 showed that the accumulation of the ampicillin resistance in bacterial population probably depended on the WWTP technology and wastewater composition. Out of the four tested resistance genes (blaTEM, blaKPC, blaNDM-1, and blaOXA-48), blaTEM and blaNDM-1 genes were the only two detected in this study. According to NGS analysis of bacterial 16 S rRNA gene, Gammaproteobacteria dominated the ampicillin-resistant bacteria of the WWTP sedimentation tanks. Their relative abundance in the bacterial population also increased during the sedimentation processes in WWTP1. It could indicate the role of the bacterial taxon in ampicillin resistance accumulation in this WWTP and show that only 9.29% of the original bacterial population from the nitrification tank is involved in the documented shifts in beta-lactam resistance of the bacterial population.

Ampicillin-resistant bacteria in amniotic fluid in cases of preterm premature rupture of membranes

Ampicillin-resistant bacteria in amniotic fluid in cases of preterm premature rupture of membranes

Anti-infective Effects of a Fish-Derived Antimicrobial Peptide Against Drug-Resistant Bacteria and Its Synergistic Effects With Antibiotic.

Antimicrobial peptides (AMPs) play pivotal roles in protecting against microbial infection in fish. However, AMPs from topmouth culter (Erythroculter ilishaeformis) are rarely known. In our study, we isolated an AMP from the head kidney of topmouth culter, which belonged to liver-expressed antimicrobial peptide 2 (LEAP-2) family. Topmouth culter LEAP-2 showed inhibitory effects on aquatic bacterial growth, including antibiotic-resistant bacteria, with minimal inhibitory concentration values ranging from 18.75 to 150 μg/ml. It was lethal for Aeromonas hydrophila (resistant to ampicillin), and took less than 60 min to kill A. hydrophila at a concentration of 5 × MIC. Scanning electron microscope (SEM) and SYTOX Green uptake assay indicated that it impaired the integrity of bacterial membrane by eliciting pore formation, thereby increasing the permeabilization of bacterial membrane. In addition, it showed none inducible drug resistance to aquatic bacteria. Interestingly, it efficiently delayed ampicillin-induced drug resistance in Vibrio parahaemolyticus (sensitive to ampicillin) and sensitized ampicillin-resistant bacteria to ampicillin. The chequerboard assay indicated that topmouth culter LEAP-2 generated synergistic effects with ampicillin, indicating the combinational usage potential of topmouth culter LEAP-2 with antibiotics. As expected, topmouth culter LEAP-2 significantly alleviated ampicillin-resistant A. hydrophila infection in vivo, and enhanced the therapeutic efficacy of ampicillin against A. hydrophila in vivo. Our findings provide a fish innate immune system-derived peptide candidate for the substitute of antibiotics and highlight its potential for application in antibiotic-resistant bacterial infection in aquaculture industry.

Antibiotic resistant bacteria in surface waters in Slovakia

Abstract This work deals with the occurrence of selected antibiotic resistant bacteria in Slovak surface waters. Total and antibiotic resistant coliform bacteria, enterococci and coagulase positive staphylococci were determined in 34 samples of surface water from rivers and still waters (dams, natural lakes, thermal bath) some of them used for recreational swimming. Sampling was performed during summer season 2017 (July and August). The number of total coliforms ranged from 1.74 log CFU/10 mL to 3.69 log CFU/10 mL. Coliform bacteria were registered in each tested sample. The highest number was observed in the sample from river Hron. Majority of samples contained ampicillin and tetracycline resistant bacteria. Enterococci were determined in 70 % of samples ranging from 0.78 log CFU/10 mL to 3.81 log CFU/10 mL. The highest number of enterococci was observed in river Váh. Ampicillin and vancomycin resistance prevailed over ciprofloxacin and gentamicin resistance. Coagulase positive staphylococci were present in 91 % of samples in the range of 0.70—3.03 log CFU/10 mL. Antibiotic resistant coagulase positive staphylococci were observed only in 32 % of samples, predominantly from rivers. In these samples, chloramphenicol resistance predominated. In three samples of water used for recreational purposes, the limit value for enterococci and E. coli according to Slovak legislation (Decree no. 308/2012 Coll.) for the quality of water in natural swimming pools during bathing season was exceeded.

Ampicillin-mediated functionalized gold nanoparticles against ampicillin-resistant bacteria: strategy, preparation and interaction studies

Antibiotic resistance is a highly challenging concern of infectious diseases, and it requires a rational approach to overcome. Through this work, we have synthesized ampicillin-capped gold nanoparticles (Amp-Au NPs) and studied its interaction with bacterial cells. In this process of synthesis, the primary amine group of ampicillin acts as both reducing as well as capping agent. In addition to synthesized gold nanoparticles, the β-lactam ring remains free to interact with bacteria. This approach not only utilizes the maximum efficiency of nanoparticles and antibiotics towards ampicillin sensitive bacterial cells but also proves to be effective against ampicillin resistance bacteria. Our results illustrate that the optimized system of Amp-Au NPs was formulated by taking 1.25 mM ampicillin and 10−2 of gold ions concentration. UV–vis spectrum of gold nanoparticles and the presence of ampicillin were recorded at around 540 nm and 259 nm, respectively. Microscopic images indicate that particles are nearly spherical and are in size range between 25 and 50 nm. Moreover, formulated Amp-Au NPs show successful accumulation onto the surface of the bacterial cell as a result of which pores were formed into the bacterial membrane. The entry of nanoparticles into bacterial cells was validated through both atomic force microscopy and fluorescent microscopy. The adhesive properties of this coating material and its stability in various pH, i.e. pH 3, pH 7 and pH 10 conditions, could make them a good candidate in the prevention of biofilm formation. Amp-Au NPs show promising antimicrobial activity against ampicillin resistance Escherichia coli bacteria. Furthermore, antimicrobial studies indicate that the efficacy of Amp-Au NPs increased against both ampicillin sensitive and ampicillin resistance bacteria up to sixteen folds and four folds respectively.

Bacteria From the Multi-Contaminated Tinto River Estuary (SW, Spain) Show High Multi-Resistance to Antibiotics and Point to Paenibacillus spp. as Antibiotic-Resistance-Dissemination Players.

Bacterial resistance to antibiotics is an ever-increasing phenomenon that, besides clinical settings, is generally assumed to be prevalent in environmental soils and waters. The analysis of bacteria resistant to each one of 11 antibiotics in waters and sediments of the Huelva’s estuary, a multi-contaminated environment, showed high levels of bacteria resistant mainly to Tm, among others. To further gain knowledge on the fate of multi-drug resistance (MDR) in environmental bacteria, 579 ampicillin-resistant bacteria were isolated tested for resistance to 10 antibiotics. 92.7% of the isolates were resistant to four or more antibiotic classes, indicating a high level of multi-resistance. 143 resistance profiles were found. The isolates with different MDR profiles and/or colony morphologies were phylogenetically ascribed based on 16S rDNA to phyla Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes, including 48 genera. Putative intrinsic resistance was detected in different phylogenetic groups including genera Altererythrobacter, Bacillus, Brevundimonas, Erythrobacter, Mesonia, Ochrobactrum, and Ponticaulis. Correlation of the presence of pairs of the non-intrinsic-resistances in phylogenetic groups based on the kappa index (κ) highlighted the co-habitation of some of the tested pairs at different phylogenetic levels. Maximum correlation (κ = 1.000) was found for pairs CzR/TcR in Betaproteobacteria, and CcR/TcR and EmR/SmR in Sphingobacteriia at the class level, while at the genus level, was found for CcR/TcR and NxR/TmR in Mesonia, CzR/TmR and EmR/KmR in Paenibacillus, and CcR/EmR and RpR/TcR in Pseudomonas. These results could suggest the existence of intra-class and intra-genus-transmissible genetic elements containing determinants for both members of each pair. Network analysis based on κ values higher than 0.4 indicated the sharing of paired resistances among several genera, many of them centered on the Paenibacillus node and raising the hypothesis of inter-genera transmission of resistances interconnected through members of this genus. This is the first time that a possible hotspot of resistance interchange in a particular environment may have been detected, opening up the possibility that one, or a few, bacterial members of the community could be important promoters of antibiotic resistance (AR) dissemination in this environment’s bacterial population. Further studies using the available isolates will likely give insights of the possible mechanisms and genetic elements involved.

The presence of bla1, bla-SHV and bla-TEM in ampicillin-resistant bacteria from agricultural soil samples

Antibiotic resistance in the environment occurs naturally in bacteria, and is a growing problem due to the use of antibiotics both in human and animal medicine. β-lactamases are the most studied group of antibiotic resistant genes, as these enzymes hydrolyze penicillin, ampicillin, and other β-lactam antibiotics. The purpose of this study was to determine if there was a statistically significant difference between numbers of copies of β-lactamase genes (bla1, bla-TEM, bla-SHV) from ampicillin-resistant bacteria in soil samples from a horse pasture and a crop field. Colony counts suggested there was a significant difference (p 0.05) in bacteria from each soil sample, but there was a significant difference in the presence of bla-SHV (p = 0.0061). A significant difference in ampicillin-resistant colonies and bacteria with bla-SHV suggests that ampicillin used in the horses may be selecting for ampicillin resistance in the soil bacteria. There may also be high concentrations of other ampicillin-resistant genes present in agricultural rich soils, particularly in animal pastures. Future studies need to be undertaken to document the level of antibiotic resistance found in animal pastures to understand the impact this may have on animal and human health.

Microbial diversity and antibiotic resistance in a final effluent-receiving lake

Wastewater treatment plants have been recognised as hotspots for antibiotic resistance genes and antibiotic-resistant bacteria which enter the environment. However, the persistence of these genes and bacteria in receiving ecosystems remains poorly understood. The aim of the study was to evaluate the effect of final effluent release on microbial diversity and the antibiotic resistance gene pool in a final effluent-receiving lake. The numbers of total culturable heterotrophs and unculturable bacteria (represented as the 16S rRNA gene copy number) were significantly reduced during the treatment process. The number of ampicillin-resistant bacteria was higher in the sediment than in water samples, suggesting accumulation of ampicillin-resistant bacteria in freshwater sediments. Using an exogenous method, we captured 56 resistance plasmids which were further characterised. Next-generation sequencing revealed that the microbial phyla represented in the studied metagenomes were typical of corresponding environments. The highest relative abundance of antibiotic resistance genes was observed in the final effluent, suggesting that a considerable number of genes were released from the wastewater treatment plant. However, the lowest relative abundance and lowest diversity of the genes in the lake water, compared to the other studied metagenomes, suggest a negligible effect of treated sewage release on antibiotic resistance within water microbial communities of the lake. Furthermore, uncontrolled sewage dumping into this reservoir in the past as well as lower quality of the water upstream of the lake indicated that the wastewater treatment plant protected the studied ecosystem.

Thermophilic anaerobic digestion is an effective treatment for reducing cefazolin-resistant bacteria and ESBL-producers in dairy manure

The application of thermophilic anaerobic digestion (TAD) treatments to dairy manure in a biogas plant was evaluated to investigate whether the prominent countermeasure was sufficient for the dissemination of antimicrobial-resistant (AMR) bacteria in the dairy industry. To determine the changes in the number of AMR bacteria in dairy manure after TAD, cefazolin-resistant (CEZ-R) and ampicillin-resistant (AMP-R) bacteria in dairy manure and digestate were quantified by plate spread methods performed with combinations of antimicrobials added to agar plates and selective and differential agar plates. In addition, extended-spectrum β-lactamase (ESBL)-producing bacteria were also quantified to evaluate the effect of TAD on plasmid-borne resistant bacteria. CEZ-R and AMP-R bacteria were widely reduced after TAD compared with the susceptible bacteria against these antimicrobials. The classification into E. coli, other coliforms, and non-coliform bacteria revealed that CEZ-R and AMP-R coliform bacteria were more significantly reduced than non-coliform bacteria by TAD. Moreover, ESBL-producing bacteria were reduced significantly among CEZ-R bacteria. From these results, TAD appears to be a useful treatment to counter the dissemination of AMR bacteria in dairy manure by the preferential elimination of AMR bacteria.

Investigation of the Antimicrobial Susceptibility Profile, Virulence Genes, and Epidemiologic Relationship of Clinical Salmonella Isolates.

The objectives of this study were to investigate the epidemiologic relationship, prevalence of the beta-lactamase and virulence genes of clinical ampicillin-resistant Salmonella enterica. In vitro ampicillin susceptibilities of 117 Salmonella enterica isolates obtained between 2011-2012 from Ege University Hospital, Bacteriology Laboratory of Medical Microbiology Department were examined using disc diffusion assays in accordance with the CLSI guidelines. The MIC levels in the ampicillin-resistant bacteria were determined using the broth microdilution method. The resistant strains were serotyped by the Public Health Institution. Epidemiologic relations of resistant strains were evaluated using ERIC-PCR. The presence of beta-lactamase genes and virulence factors were detected using PCR. The 117 S. enterica strains had ten isolates that were resistant to ampicillin, and the MIC range of ampicillin was found as 512-128 μg/mL. Ampicillin-resistant strains were susceptible to nalidixic acid, ciprofloxacin, cefotaxime, sulfamethoxazole/trimethoprim. Four different serotypes were identified and isolates were grouped into seven clusters. Five isolates carried blaTEM , and two carried the blaCTX-M gene. However, it was determined that blaSHV and blaPER genes did not exist in these strains. Virulence genes invA, pipD, and sopB were found in all isolates. sifA, pefA, and sopE genes were found in seven, four, and three isolates, respectively. Our data suggest that the rate of ampicillin resistance in S. enterica isolates was 8.5% in the two year period, but this ratio was generally lower than rates abroad. blaCTX-M and blaTEM genes could be responsible for ampicillin resistance. The blaSHV gene, which is highly prevalent in our country, was not found in any strains. sopB and pipD genes, which might be associated with beta-lactam resistance, were found in all strains. It is also noteworthy that the three isolates containing the sopE gene, which is associated with epidemic cases, were of the same serotypes and epidemiologic clusters.

Tackling antimicrobial resistance in food-producing animals

Tackling antimicrobial resistance in food-producing animals

Construction of a nucleic acid vaccine against infectious hematopoietic necrosis, and the influence of resistance genes on resistance of environmental bacteria

PDF HTML阅读 XML下载 导出引用 引用提醒 传染性造血器官坏死病核酸疫苗的构建及其抗性基因对环境细菌抗性的影响 DOI: 作者: 作者单位: 1. 中国水产科学研究院 黑龙江水产研究所, 黑龙江 哈尔滨 150070;2. 上海海洋大学 水产与生命学院, 上海 201306 作者简介: 李渊(1989-),硕士研究生,从事鱼类病毒学研究.E-mail:1154662843@qq.com 通讯作者: 中图分类号: S941 基金项目: 黑龙江省应用技术研究与开发计划项目（GA13B401）；中央公益性事业单位基本科研业务费专项经费项目（HSY20-1514，2016HY-ZD0504）. Construction of a nucleic acid vaccine against infectious hematopoietic necrosis, and the influence of resistance genes on resistance of environmental bacteria Author: Affiliation: 1. Heilongjiang River Fishery Research Institute Chinese Academy of Fishery Sciences, Harbin 150070, China;2. College of Fishery and Life Science, Shanghai Ocean University, Shanghai 201306, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:本研究以传染性造血器官坏死病毒（infectious hematopoietic necrosis virus，IHNV）分离株XJ-13为研究对象，克隆其糖蛋白（glycoprotein，G）基因并连接到商业化载体pcDNA3.1（+），成功构建了真核表达载体pIHNxj-G。为了检测该载体作为核酸疫苗的可能性，本研究以2 μg/尾的剂量采用背鳍基部注射免疫虹鳟（的剂量利用IHNV-XJ-13对虹鳟进行腹腔注射攻毒；在免疫后第4天及第7天，利用Real-time PCR技术检测虹鳟头肾及接种部位肌肉组织基因表达情况；在免疫后第4天及30天检测虹鳟血清IHNV中和抗体效价；在免疫后65 d内，分别于不同时间点采集循环水池里的粪便、水以及虹鳟的肠内容物，进行氨苄青霉素抗性菌的分离鉴定。攻毒试验结果显示，核酸疫苗在免疫后第4天和第30天的相对保护率均高于90%；基因在头肾和接种部位肌肉中均显著上调表达；中和抗体效价测定结果显示，在免疫后第4天，所有血清中均不存在中和抗体（效价均<20）；而在免疫后第30天，10尾虹鳟中有8尾血清中存在中和抗体，最高效价为160；抗性菌分离结果显示，分离到的氨苄青霉素抗性菌均是天然具有氨苄青霉素抗性的气单胞菌（ sp.），并未分离到包括大肠杆菌在内的任何具有氨苄青霉素抗性的指示菌，且实验组和对照组的氨苄青霉素抗性菌的种类和数量均没有发生统计学意义的改变。本研究提供了具有良好保护效果的IHN核酸疫苗，并为IHN核酸疫苗的安全评价提供了基础数据。 Abstract:In this study, the glycoprotein (G) gene of the infectious hematopoietic necrosis virus (IHNV) isolate XJ-13 was cloned and inserted into a commercial vector pcDNA3.1 (+) to construct a nucleic acid vaccine (pIHNxj-G). Rainbow trout (5±0.5) g were immunized using this vaccine via the base of the dorsal fin at a dose of 2 μg vaccine per fish. At 4 and 30 days post-vaccination (d.p.v.), the rainbow trout were challenged by IHNV-XJ-13 at a dose of 100 TCID50 by intraperitoneal injection. Expression of the gene in the head kidney and muscle from the vaccine delivery site was detected by real-time PCR at 4 and 7 d.p.v., respectively. During the following 65 days, fecal matter, water, and intestinal contents of the rainbow trout were collected at different time points to identify ampicillin-resistant bacteria. The results of the challenge test showed that the relative protection rate of the nucleic acid vaccine was higher than 90% at 4 and 30 d.p.v. The results of gene was significantly up-regulated in the head kidney and muscle from the vaccine delivery site. Neutralizing antibody titers showed that there was no neutralizing antibody (titer<20) in any of the sera at 4 d.p.v. At 30 d.p.v., neutralizing antibodies were detected from 8 of 10 serum samples, and the highest titer was 160. The ampicillin-resistant bacteria isolated in this study mainly belonged to sp., which are naturally resistant to ampicillin. However, no indicator bacteria like were isolated, and there were no significant differences in the number or the species of the isolated ampicillin-resistant bacteria between the vaccination group and the control. This study not only provided an effective IHNV DNA vaccine, but also provided supportive data for the safety evaluation of the IHNV DNA vaccine. 参考文献 相似文献 引证文献

Antibiotic resistant bacteria in urban sewage: Role of full-scale wastewater treatment plants on environmental spreading

The presence of antibiotic resistant bacteria (ARB) in wastewater was investigated and the role of wastewater treatment plants (WWTPs) in promoting or limiting antibiotic resistance was assessed. Escherichia coli (E. coli) and total heterotrophic bacteria (THB) resistance to ampicillin, chloramphenicol and tetracycline was monitored in three WWTPs located in Milan urban area (Italy), differing among them for the operating parameters of biological process, for the disinfection processes (based on sodium hypochlorite, UV radiation, peracetic acid) and for the discharge limits to be met. Wastewater was collected from three sampling points along the treatment sequence (WWTP influent, effluent from sand filtration, WWTP effluent).Antibiotic resistance to ampicillin was observed both for E. coli and for THB. Ampicillin resistant bacteria in the WWTP influents were 20–47% of E. coli and 16–25% of THB counts. A limited resistance to chloramphenicol was observed only for E. coli, while neither for E. coli nor for THB tetracycline resistance was observed. The biological treatment and sand filtration led to a decrease in the maximum percentage of ampicillin-resistant bacteria (20–29% for E. coli, 11–21% for THB). However, the conventionally adopted parameters did not seem adequate to support an interpretation of WWTP role in ARB spread. Peracetic acid was effective in selectively acting on antibiotic resistant THB, unlike UV radiation and sodium hypochlorite. The low counts of E. coli in WWTP final effluents in case of agricultural reuse did not allow to compare the effect of the different disinfection processes on antibiotic resistance.

Enhanced Antibiotic Resistant Bacteria Removal from Wastewater Treatment Plant by Different Disinfection Technologies

Based on the removal of total heterotrophic bacteria (HPC) and antibiotic resistant bacteria (ARB), including the ampicillin resistant bacteria (AMP), erythromycin resistant bacteria (ERY), tetracycline resistant bacteria (TET), kanamycin resistant bacteria (KAN), and ciprofloxacin resistant bacteria (CIP), this study investigates the enhanced removal performance of ARB by different disinfection technologies. The experimental results showed that ARB removal by ultraviolet (UV) disinfection from the wastewater treatment plant (WWTP) was only 18.2%-40.9% and AMP was the highest in content. ERY could be selectively removed by different disinfection technologies; however, there was no distinguished selective removal performance for other four types of ARB (P<0.05). For ARB, COD and NH4+-N removal, the optimal ozone, chlorination, and UV concentration or dosage were 5.0 mg·L-1, 25.0 mg·L-1, and 45.0 mJ·cm-2, respectively, and the corresponding ARB removal efficiencies were 45.5%-74.5%, 66.1%-85.5%, and 68.6%-85.5%. Furthermore, the combined UV and chlorine treatment could achieve better ARB removal performance.