جستجوی مقالات مرتبط با کلیدواژه "آنتی بیوتیک" در نشریات گروه "زیست شناسی"

The purpose of this study was to investigate the antimicrobial activity of bacteriocins produced by lactic acid bacteria against beta-lactamase producing bacteria and to evaluate its synergism effect with some antibiotics.

In this study, bacteriocin was isolated from Lactobacillus acidophilus strains, and then the effect of produced bacteriocin against 3 pathogenic bacterial strains, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa was investigated by serial dilution method. The effectiveness of bacteriocin extract alone and in combination with commercial antibiotics against clinical pathogens was determined using the disk diffusion method in three replicates.

The results showed that all Pseudomonas aeruginosa and Acinetobacter baumannii strains were beta-lactamase positive. This study showed a statistically significant difference in bacteriocin-antibiotic synergism activity for ceftazidime, levofloxacin, and piperacillin in Pseudomonas aeruginosa strains and in Acinetobacter baumannii strains for tetracycline, gentamicin, and ceftazidime.

Lactobacillus acidophilus bacteriocin along with some antibiotics showed synergism effect in beta-lactamase producing strains of Pseudomonas aeruginosa, Acinetobacter baumannii and Escherichia coli.

Since the advent of antibiotics, selective pressure on microorganisms has caused the formation of resistant types. Different generations of antibiotics have been designed and used to fight pathogens, but at the same time, more resistant types of pathogens have been spread, so it is necessary to use new strategies to deal with infectious agents. The development of nanoscience in the field of medicine was a suitable solution for this purpose, and pharmaceutical nanocarriers were developed. Liposomes are nanocarriers with a lipid body whose features such as biocompatibility, bioavailability, targeted transfer, amphiphilic properties, integration with membranes, slow and controlled drug release have attracted the attention of researchers. In this review article, an attempt has been made to provide information about the benefits of this drug system by studying scientific documents in the field of antibiotic-carrying liposomes.

Continuous increase and accumulation of antibiotics in the environment; is a danger due to their toxicity and longevity. Antibiotics, as an emerging pollutant, have harmful effects on the ecosystem. Microalgae, as the primary producers of life, are considered one of the pollution indicators due to their high sensitivity. Since microalgae live in aquatic environments and are at the base of the marine food chain, understanding the interactions between microalgae and antibiotics is critical for assessing the ecological risk of antibiotics in aquatic environments. Knowing the damages on vital processes, including photosynthesis and the creation of oxidative stress and the mechanisms of these effects, can be effective in preserving and sustaining aquatic ecosystems. In this study, the effect of antibiotics azithromycin, tetracycline and erythromycin on microalgae was investigated.

The study aimed to examine the chronic toxicity effects of oxytetracycline (OTC) and florfenicol (FLO) antibiotics, commonly used in shrimp farms, on the growth performance, chlorophyll a content, and total protein of Chaetoceros muelleri microalgae. C. muelleri, initially at a density of 4,000 cells per milliliter, underwent exposure to oxytetracycline at doses of 7.43 milligrams per liter and florfenicol at 5.20 milligrams per liter for 12 days. Subsequent assessments focused on growth metrics, chlorophyll a content, and total protein. The findings highlighted a significant reduction in the growth, chlorophyll a content, and protein synthesis of C. muelleri following exposure to both OTC and FLO antibiotics (p < 0.05). Moreover, the study revealed that FLO exhibited higher toxicity toward C. muelleri compared to OTC. The observed decline in growth, chlorophyll a content, and protein synthesis in C. muelleri under OTC and FLO exposure could be attributed to the inhibitory impact of these antibiotics on cellular respiration and protein synthesis pathways.

The savory(Satureja macrantha) belongs to the mint family, it is an annual or multi-year plant, Iran has 12 annual or multi-year grass species. In many studies, antimicrobial, antiviral, antifungal, antispasmodic, stomach strengthening and digestion facilitating properties of this genus have been reported. Nisome is a important surfactant-based non-ionic vesicle. Niosomes offer several advantages for drug delivery systems, including osmotically active, chemical stability and long retention time compared to liposomes. In the present study, niosomes extracted from as a drug are dynamically evaluated by calorimetric method (Folin's method). In this study niosomes formulation containing Satureja macrantha extract, in order to achieve the optimal formulation, different formulations were prepared based on the molar ratio of Span 60/Tween 60, cholesterol and with a sonication time of 7 minutes. The niosomes extracted from the savory plant significantly inhibited the activity of the two bacteria(Staphylococcus aureus ) and (Escherichia coli) tested in the present study.

Mechanical ventilation-associated pneumonia (VAP) is a common nosocomial disease defined as occurring 48 hours after initiation of mechanical ventilation. In the present study, the effect of oral consumption of the traditional medicinal product (a product containing honey, ginger, cardamom, alpinia, saffron, mastic, and cinnamon) on the prevention and treatment of VAP was investigated. The study was a randomized clinical trial, conducted on 41 intubated patients admitted to Loghman Hakim and Shohadaye Tajrish hospitals in Tehran during 2019-2020. Patients were divided into two groups including 19 cases (control) and 22 cases (intervention). In the intervention group, patients received 10 ml of mixed honey syrup (manufactured by Niyak Gorgan Pharmaceutical Factory) three times a day by gavage. In all patients, variables such as demographic information, underlying diseases, medications, duration of intubation, rate of VAP, and clinical and laboratory information were recorded and evaluated. The incidence of VAP based on the CPIS score was 50% and 47.36%  in the intervention and control group, respectively, showing no significant difference ​​(P≤0.558). Also, based on the analysis of the obtained data, no significant difference was found between the days of antibiotic treatment in patients with pneumonia. Based on the findings, this product had no effect on the rate of pneumonia caused by mechanical ventilation devices, but its positive effects were evident in stopping fever faster in the patients of the intervention group.

Silver nanoparticles have been widely used due to their anti-bacterial activities and anticancer properties. The aim of this study was to investigate the antimicrobial effects and cell toxicity of silver nanoparticles synthesized using extracts of chamomile on three neoplastic cell lines (A549, MCF-7 and HeLa).

Silver nanoparticles were biologically synthesized using extracts of chamomile. After physical and chemical evaluation of the synthesized nanoparticles, their antimicrobial properties were estimated on Escherichia coli and Staphylococcus aureus. Finally, the inhibitory effect of synthesized nanoparticles evaluated by using MTT technique on 3 neoplastic cell lines.

  The average size of nanoparticles synthesized by the extract of chamomile were 19 nm. The synthesized nanoparticles could have a significant inhibitory and lethal effect on the two named bacteria. silver nanoparticles were able to show a 50% inhibitory effect on different cell lines at a concentration of 50 μg/ml.

Based on the results, it can be stated that medicinal plants can be used in the successful biosynthesis of silver nanoparticles. After human studies and tests, chamomile-based silver nanoparticles can be used as effective therapeutic agent in the treatment of some cancers due to their coating of effective secondary metabolites and the release of silver ions (Ag+).

Streptococcus iniae and Lactococcus garvieae bacteria are among the most important fish pathogens. The aim of this study was to determine antimicrobial resistance patterns of S. iniae and L. garvieae isolated from diseased rainbow trout. With respect to outbreak of disease, the survey was carried out in warm seasons using 100 rainbow trout fish with clinical symptoms of disease. Bacteria were cultured from Kidney tissue of fish using standard methods. The antibiotic resistance pattern of strains was studied based on CLSI protocol. The results of the research showed that S. iniae isolates were more sensitive to enrofloxacin, florfenicol, erythromycin and lincospectin, and more resistant to sulfamethoxazole-trimethoprim, tetracycline, fosfomycin, ampicillin, lincomycin and flemequine, respectively. Furthermore, L. garvieae isolates were more sensitive to erythromycin, enrofloxacin, florfenicol, flemequine and lincospectin, and more resistant to sulfamethoxazole-trimethoprim, fosfomycin, tetracycline and ampicillin.

Metal nanoparticles synthesized using medicinal plants are used in anti-cancer and antimicrobial studies due to their unique physicochemical properties, high safety and low cost.

Silver nanoparticles were synthesized using extracts of hyssop and marjoram. After studying the properties of the synthesized nanoparticles, two gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria were used to evaluate the antimicrobial effect of the synthesized nanoparticles. Finally, the anti-cancer effect of synthesized silver nanoparticles on 3 cancer cell lines was evaluated by MTT method.

The results showed that the synthesized nanoparticles were spherical in shape and their average size was between 15 and 26 nm. X-ray diffraction test also confirmed the successful synthesis of nanoparticles. The results of antimicrobial test showed that the synthesized silver nanoparticles had a significant antimicrobial effect on both bacteria. The anti-cancer effect of the synthesized nanoparticles was similar on all 3 cell lines. However, with increasing the concentration of nanoparticles on the survival of cancer cells decreased, indicating a direct dose interaction on the inhibitory rate of silver nanoparticles. Discussion and

Medicinal plants can be used in the synthesis of silver nanoparticles. The synthesized nanoparticles, due to their coating of secondary metabolites and the release of silver ions (Ag+ ), can be used as effective therapeutic agents in the treatment of various cancers

Actinomycetes are filamentous and gram-positive bacteria living as free-living, saprophyte, and sometimes in symbiosis with plants. These bacteria could be isolated from all ecosystems including soil, water, marine sediments and especially hot waters. Marine actinobacteria are known as the producers of a vast range of secondary metabolites. Any actinobacterial strain has the genetic potential for the production of 10-20 of the secondary metabolites. About 23000 antibiotic types were discovered from microorganisms which according to the estimations, about 10000 types have been isolated from actinobacteria. The secondary metabolites produced by marine actinobacteria have an extensive range of biological activities such as antibacterial, antifungal, anti-cancer, cytotoxic, cytostatic, ant-inflammatory, anti-parasite, anti-malaria, antiviral, anti-oxidant and anti-angiogenesis, etc.

In the present study, water and sediment samples from the Persian Gulf at the Bushehr Atomic Energy Beach were collected for Actinobacteria isolation. For the cultivation of these samples, 7 culture medium types were used. For the identification of the gathered isolates, morphological properties, biochemical tests, and molecular studies (e.g. PCR) were investigated.

Twenty-four isolates of Actinobacteria were isolated from water and sediment samples of the Persian Gulf coast. Eighteen of the isolates have antibacterial activities. Seventy-five persent of the isolates were antibiotic producers and 95% of the gathered substances from these 18 strains had an antibacterial effect against gram-positive bacteria and 60% against gram-negative bacteria. Also, 60% of these substances were effective against both bacteria groups.

The abundance of marine actinobacteria in new sources of the Persian Gulf and the extension of this sea’s coat indicates the potential capability of this source for investigation in the scope of attaining new antibiotics.

Plant Associated Bacteria are one of the most important elements of plant ecosystems. These bacteria live internally (endophytes) or externally (epiphytes) in different plants organs and have various effects on the life cycle of plants. These bacteria are constantly exposed to different antibacterial compounds which are secreted from plants and other epiphytic microorganisms in their natural habitat. Plant-associated bacteria deal with these toxic compounds in a variety of ways, one of which is the use of efflux systems. An active efflux mechanism is responsible for the transportation of antibacterial compounds out of the cell. This process is associated with energy consumption which is provided from ATP hydrolysis or electrochemical gradient. These pumps are protein vectors that express from chromosome or plasmid and not only have critical rule in drug resistance, also have other physiological proceeds. The rule of efflux systems in plant-associated bacteria and their relation with transcription regulatory are discuss in this article.

Nude mice are immunodeficient, commonly used model organisms for studying human diseases. Despite the high purchase price and maintenance cost of these animals, few studies have aimed to eradicate inevitable infectious complications which may arise during in-vivo studies. The current project is a practical guideline for detecting and elimination of possible infections developed in nude mice.

Followed by transplantation of human leukemic cell lines into C57BL/6 nude mice, body weights were monitored daily. After a sudden death of 7 mice during 4 consecutive days, all beddings were discarded and cages, food and water bottles were disinfected immediately. Automated blood culture analyses were carried out using radiometric BACTEC systems, and specific antibiotics were administered based on applied microbial growth inhibition assays.

Proteus vulgaris and Klebsiella pneumoniae were identified, respectively, according to the radiometric assays. According to the antimicrobial susceptibility tests, 132mg/kg ciprofloxacin was administered orally for 2 weeks, followed by 500mg/kg cefixime for one week. Meanwhile, low-dose cefixime (132 mg/kg) was applied as a prophylactic treatment. Automated blood cultures showed elimination of both bacterial infections followed by demand treatments. Low-dose antibiotic prophylaxis saved uninfected mice from developing infections.

Results showed that precise monitoring of nude mice health conditions help early detection of the possibly grown infections. Ciprofloxacin and cefixime are the antibiotics of choice for eradication of Proteus vulgaris and Klebsiella pneumoniae. On the other hand, low-dose antibiotic prophylactic treatment may rescue these expensive animals from possible infections and provide suitable environment for performing in-vivo experiments.

This experiment was conducted to investigate the effects of different levels of oregano extract (OE) o performance in broiler chickens. A total of 360 male chicks in a completely randomized design with 5 treatments, 4 replicates of 16 birds were distributed and reared under experimental same conditions. During experimental period (1 d until end period), drinking water of the control group had no any additive while antibiotic (0.0125 % Erythromycin), 1.5, 3 or 4.5% OE were added respectively to other 4 experimental groups. The findings indicated that the use of OE affected significantly feed intake, body weight gain and feed conversion ratio in broiler chickens. In 11-24 d period, the highest feed intake was obtained in groups fed 4.5% OE or antibiotic. Also in this period, feeding 3 or 4.5% OE or antibiotic to broilers caused the significant highest weight gain (P<0.05). in overall period, using 4.5% OE caused significantly the highest weight gain and also, 3 and 4.5% OE significantly decreased feed conversion ratio in broiler chickens. In conclusion, using OE especially in level of 4.5% in broiler drinking water has beneficial effects on performance parameters and therefore can be applied as a suitable replacement for antibiotic in broiler chickens.

Siderophores are low molecular weight organic molecules produced by microorganisms under iron-restricted conditions. These metabolites are responsible for the transport of iron into microorganisms and have a high affinity to bind to ferric iron (Fe3+) and produce iron chelates. Siderophores can be divided into three main groups: catechols, hydroxamates, and carboxylates, depending on the parts that bind to iron. Of course, siderophores that have more than one type of iron ligand group are classified into a mixed category. Siderophores are used in ecology, agriculture, bioremediation and medicine. In this article, the synthesis pathway and function of siderophores, their role as antibiotics and their use as non-antibiotic drugs have been investigated. Other applications of siderophore in various industries are also briefly mentioned.

Charcoal rot caused by Macrophomina phaseolina is one of the most important soil borne diseases with a broad host range including bean, which annually brings a significant damage to this plant. Biological control of charcoal rot is very important because its chemical control harms the environment, microflora and soil fertility. Chemical control of charcoal rot is also difficult and sometimes ineffective. Fluorescent Pseudomonads are able to increase plant growth and inhibit the development of plant pathogens by producing and secreting antibiotics, enzymes, siderophores, and plant hormones. In this study, infected bean plants by M. phaseolina were collected from infected bean fields of Khorramabad (Lorestan Province, Iran) in the summer of 2015. Virulence of fungal isolates was evaluated in a greenhouse and one isolate with the highest pathogenicity was chosen for further experiments. The biocontrol potential of eight Pseudomonas fluorescens strains, whose biocontrol abilities were proved in previous studies, was examined against M. phaseolina in vitro. The growth inhibition of M. phaseolina was examined by dual culture test and the antifungal activity of bacterial volatile and nonvolatile metabolites. P. fluorescens UTPf125, which showed the highest inhibitory effect on the mycelial growth, was selected for greenhouse tests. UTPf125 strain led to a significant reduction (%50) of disease severity and increased fresh and dry weight significantly. Phenol compounds were evaluated 1, 3, 5, 7 and 9 days after inoculation by pathogen. The results showed that the highest value of total phenol content was obtained on the third and fifth days after inoculation, decreasing on the seventh and ninth days.

The occurrence of extended-spectrum beta-lactamases-producing bacteria is an important public health issue. The aim of this study was to investigate phenotypic and genotypic characteristics regarding the presence of extended spectrum β-lactamase ctx-m, per and ver producing Escherichia coli isolated from raw dairy samples. For this purpose, E. coli were isolated from 247 raw dairy samples (milk and cheese) in Yasooj in 2015-2017, and the isolates were screened for antibiotic resistance, extended spectrum β-lactamase and the presence of ctx-m, per and ver. In total, 200 isolates were selected. The highest frequency of resistance in isolates was against tetracycline (96.5%) and ampicillin (95.5%) antibiotics and the lowest against imipenem (12.5%), In addition, multidrug resistance against four or more antibiotics was observed in some isolates. Extended spectrum β-lactamase resistance was detected in 86 isolates (43%) and ctx-m, per and ver genes were detected in 82, 0 and 7 E. coli isolates, respectively. These findings demonstrated that raw dairy products may be reservoirs for the dissemination of β-lactam antibiotics and that resistance genes could be transmitted to humans through the food chain.

The spread of antibiotic residues increases the burden of antibiotic resistance microorganisms. The purpose of this study was to determine the antibiotic resistance pattern in isolated bacteria from Isfahan soils. The soil samples collected from agricultural lands (19 samples) and non-agricultural (industrial) (16 samples). The resistant bacterial population was determined using five antibiotics including erythromycin, vancomycin, and co-trimoxazole (0.5 mg/L), gentamicin (1 mg/L) and, penicillin G (2mg/L) and identified by standard cultural, morphological and biochemical characteristics. Antibiotic susceptibility of the isolates determined by minimum inhibitory concentration (MIC) by macro broth dilution. Subsequently, minimum bactericidal concentration (MBC) and multiple antibiotic resistance (MAR) profiles were determined. A total of 152 bacteria from different genera such as Staphylococcus, Corynebacterium and Bacillus sp were determined. The incidence of gentamicin and erythromycin-resistant bacteria were highest in agricultural and industrial soils, respectively. The MIC and MBC concentration of penicillin G were significantly higher than other antibiotics. Results revealed that 84% of isolates were MAR which half of them were tetra and penta-resistance to antibiotics. Many factors such as the Zayanderud River and using of livestock is affected by bacterial resistance in soil and water.

Myxobacteria are soil bacteria that move by gliding and have an astonishing life cycle culminating in fruiting body formation. The myxobacterial strain no.118 was isolated from unexplored soil of Koohrang County, Chaharmahal-o-Bakhtiari Province and tested for potential antimicrobial activity against various human pathogens. On the basis of results, strain 118 significantly inhibited growth of E. coli andM. luteus therefore was used for further characterization. Analysis of morphological, biochemical and 16S rRNA gene sequence indicated that this strain belongs to the genus Myxococcus. In addition, neighbor-joining phylogenetic tree confirmed the relationships of this strain to other members of Myxococcus genera. In order to explore the potential bioactivities, extract of the fermented broth culture was prepared with organic solvent extraction method. The methanol extract was subjected to HPLC fractionation against sensitive pathogens. LC/MS analysis resulted in the identification of Myxothiazol and Althiomycinantibiotics in methanol extract of the strain no. 118.

Trimethoprim (Tr) in combination with Sulfa methoxazole (SMZ) has a wide spectrum of activity against gram positive and negative bacteria. However these drugs are usually used, numerous side effects of these drugs are reported,which consist of skin problems, blood problems, digestive, renaly and cardiovascular disease. It seems these drugs exert their side effects via potassium channel blocking and also QT interval prolongation. The aim of the current study is to study the effects of contemporaneous injection Tr and SMZ on electrocardiographic criteria in Holstein cows. To this end, 10 clinically healthy Holstein cows (5 non pregnant female and 5 male, 5 years old,about 450±25 kg) were randomly selected; then all of them were issued on electrocardiographic changes in two stages: before and after the intramuscular injection (in the neck) of Tr and SMZ (1ml of each per 10 kg body weight, twice a day for 5 successive days).and in the end cows were transferred in a calm and non-stressed place in order to take electrocardiography. A significant difference was detected in QT interval prolongation and heart rate by the drug administration Trimethoprim and Sulfa methoxazole (P