Showing papers on "Agar plate published in 2016"
12 Dec 2016
132 citations
TL;DR: Siderophores are compounds secreted under low iron stress, which act as specific ferric iron chelating agents and may be used as an alternative strategy to chemical control in the biological control of fungal phytopathogens.
100 citations
TL;DR: The role of penetration barrier in biofilm-associated drug resistance was investigated in this article, where the authors used an agar disk diffusion assay to elucidate antibiotic penetration through biofilms formed by Staphylococcus aureus, S. epidermidis, Escherichia coli and Klebsiella pneumoniae.
Abstract: Bacterial biofilms are implicated in a wide range of implant-based and chronic infections. These infections are often associated with adverse therapeutic outcomes, owing to the decreased antibiotic susceptibility of biofilms compared with their planktonic counterparts. This altered biofilm susceptibility has been attributed to multiple factors, including a reduced antibiotic penetration. Although several studies have addressed the role of penetration barrier in biofilm-associated drug resistance, it remains inconclusive. This study was done to elucidate antibiotic penetration through biofilms formed by Staphylococcus aureus, S. epidermidis, Escherichia coli and Klebsiella pneumoniae, using an agar disk diffusion assay. Penetration capacity of six antimicrobial drugs from different classes (β-lactams, aminoglycosides, tetracyclines, phenicols, fluoroquinolones and glycopeptides) through biofilms formed by standard strains and clinical isolates from catheter-related bloodstream infections (CRBSI) was elucidated by measuring their growth-inhibition zones in lawn cultures on Mueller-Hinton agar, following diffusion of an antibiotic from an overlying disk through their biofilm to the agar medium. Penetration of only select antimicrobials (vancomycin and chloramphenicol) was hindered through biofilms. There was considerable variation in biofilm-permeating capacity depending upon the genus, strain/CRBSI isolate and antibiotic tested. Furthermore, antibiotics failed to kill the biofilm cells independent of penetration, indicating that other factors contributed substantially to biofilm resistance.
93 citations
TL;DR: Various compounds with siderophore activity, including pyoverdines-Fe-complex, desferricoprogen and salicylic acid, were found to stimulate the growth of difficult-to-culture strains Prevotella sp.
Abstract: Over a third of oral bacteria are as-yet-uncultivated in-vitro. Siderophores have been previously shown to enable in-vitro growth of previously uncultivated bacteria. The objective of this study was to cultivate novel oral bacteria in siderophore-supplemented culture media. Various compounds with siderophore activity, including pyoverdines-Fe-complex, desferricoprogen and salicylic acid, were found to stimulate the growth of difficult-to-culture strains Prevotella sp. HOT-376 and Fretibacterium fastidiosum. Furthermore, pyrosequencing analysis demonstrated increased proportions of the as-yet-uncultivated phylotypes Dialister sp. HOT-119 and Megasphaera sp. HOT-123 on mixed culture plates supplemented with siderophores. Therefore a culture model was developed, which incorporated 15 μg siderophore (pyoverdines-Fe-complex or desferricoprogen) or 150 μl neat subgingival-plaque suspension into a central well on agar plates that were inoculated with heavily-diluted subgingival-plaque samples from subjects with periodontitis. Colonies showing satellitism were passaged onto fresh plates in co-culture with selected helper strains. Five novel strains, representatives of three previously-uncultivated taxa (Anaerolineae bacterium HOT-439, the first oral taxon from the Chloroflexi phylum to have been cultivated; Bacteroidetes bacterium HOT-365; and Peptostreptococcaceae bacterium HOT-091) were successfully isolated. All novel isolates required helper strains for growth, implying dependence on a biofilm lifestyle. Their characterisation will further our understanding of the human oral microbiome.
69 citations
TL;DR: Performing aerobic cultures in the presence of Bacteroides thetaiotaomicron, which produces hydrogen, allows for cultivation of Methanobrevibacter smithii and changes the ability to routinely study methanogens, which have been neglected in clinical microbiology laboratories and may be useful for biogas production.
Abstract: Culturing methanogenic archaea is fastidious, expensive, and requires an external source of hydrogen and carbon dioxide. Until now, these microorganisms have only been cultivated under strictly anaerobic conditions. We previously developed a single versatile culture medium containing sugars and anti-oxydants for cultivating all human known methanogens. Performing aerobic cultures in the presence of Bacteroides thetaiotaomicron, which produces hydrogen, allows for cultivation of Methanobrevibacter smithii which itself produces methane. To obtain colonies, we cultivated M. smithii in an agar plate in the upper part of a double chamber flask with a liquid culture of B. thetaiotaomicron in the lower compartment. We subsequently cultured four other methanogenic species for the first time and successfully isolated 13 strains of M. smithii and nine strains of Methanobrevibacter oralis from 100 stools and 45 oral samples. This procedure allows aerobic isolation and antibiotic susceptibility testing. This changes the ability to routinely study methanogens, which have been neglected in clinical microbiology laboratories and may be useful for biogas production.
59 citations
TL;DR: A modified plate assay is developed based on improved visualization of halo zone formation around the colonies on agar plates, through inclusion of an acid-base indicator dye, bromothymol blue (BTB), to modify the previously reported Aleksandrov medium.
57 citations
TL;DR: To explore the presence of phages in clinical samples, 65 clinical samples were assessed and infectious tailed phages were detected in >45% of ascitic fluid and urine samples.
Abstract: Bacteriophages are viruses that infect bacteria, and they are found everywhere their bacterial hosts are present, including the human body. To explore the presence of phages in clinical samples, we assessed 65 clinical samples (blood, ascitic fluid, urine, cerebrospinal fluid, and serum). Infectious tailed phages were detected in >45% of ascitic fluid and urine samples. Three examples of phage interference with bacterial isolation were observed. Phages prevented the confluent bacterial growth required for an antibiogram assay when the inoculum was taken from an agar plate containing lysis plaques, but not when taken from a single colony in a phage-free area. In addition, bacteria were isolated directly from ascitic fluid, but not after liquid enrichment culture of the same samples, since phage propagation lysed the bacteria. Lastly, Gram-negative bacilli observed in a urine sample did not grow on agar plates due to the high densities of infectious phages in the sample.
53 citations
TL;DR: The current study assesses the effect of two commonly used sporulation conditions on spore protein presence and finds that the core dipicolinic acid content is found to be similar in both the spore populations, it appears that the difference in wet heat resistance is connected to the differences in the coat protein composition and assembly.
Abstract: Spores are of high interest to the food and health sectors because of their extreme resistance to harsh conditions, especially against heat. Earlier research has shown that spores prepared on solid agar plates have a higher heat resistance than those prepared under a liquid medium condition. It has also been shown that the more mature a spore is, the higher is its heat resistance most likely mediated, at least in part, by the progressive cross-linking of coat proteins. The current study for the first time assesses, at the proteomic level, the effect of two commonly used sporulation conditions on spore protein presence. 14N spores prepared on solid Schaeffer's-glucose (SG) agar plates and 15N metabolically labeled spores prepared in shake flasks containing 3-(N-morpholino) propane sulfonic acid (MOPS) buffered defined liquid medium differ in their coat protein composition as revealed by LC-FT-MS/MS analyses. The former condition mimics the industrial settings while the latter conditions mimic the routine laboratory environment wherein spores are developed. As seen previously in many studies, the spores prepared on the solid agar plates show a higher thermal resistance than the spores prepared under liquid culture conditions. The 14N:15N isotopic ratio of the 1:1 mixture of the spore suspensions exposes that most of the identified inner coat and crust proteins are significantly more abundant while most of the outer coat proteins are significantly less abundant for the spores prepared on solid SG agar plates relative to the spores prepared in the liquid MOPS buffered defined medium. Sporulation condition-specific differences and variation in isotopic ratios between the tryptic peptides of expected cross-linked proteins suggest that the coat protein cross-linking may also be condition specific. Since the core dipicolinic acid content is found to be similar in both the spore populations, it appears that the difference in wet heat resistance is connected to the differences in the coat protein composition and assembly. Corroborating the proteomic analyses, electron microscopy analyses show a significantly thinner outer coat layer of the spores cultured on the solid agar medium.
44 citations
TL;DR: A one-step, spray-based application of a 2,5-dihydroxybenzoic acid solution provides a homogeneous, relatively dry coating on hydrated samples, improving spot to spot signal repeatability compared with sieved matrix application, and is easily adapted for imaging a range of agar-based biofilms.
Abstract: Matrix-assisted laser desorption/ionization imaging of biofilms cultured on agar plates is challenging because of problems related to matrix deposition onto agar. We describe a one-step, spray-based application of a 2,5-dihydroxybenzoic acid solution for direct matrix-assisted laser desorption/ionization imaging of hydrated Bacillus subtilis biofilms on agar. Using both an optimized airbrush and a home-built automatic sprayer, region-specific distributions of signaling metabolites and cannibalistic factors were visualized from B. subtilis cells cultivated on biofilm-promoting medium. The approach provides a homogeneous, relatively dry coating on hydrated samples, improving spot to spot signal repeatability compared with sieved matrix application, and is easily adapted for imaging a range of agar-based biofilms. Copyright © 2016 John Wiley & Sons, Ltd.
36 citations
TL;DR: Results suggest potential applications of these isolates or their activities (proteolytic activity or production of antimicrobials) in dairy foods production.
Abstract: Lactic acid bacteria (LAB) can be isolated from different sources such as milk and cheese, and the lipolytic, proteolytic and glycolytic enzymes of LAB are important in cheese preservation and in flavour production. Moreover, LAB produce several antimicrobial compounds which make these bacteria interesting for food biopreservation. These characteristics stimulate the search of new strains with technological potential. From 156 milk and cheese samples from cow, buffalo and goat, 815 isolates were obtained on selective agars for LAB. Pure cultures were evaluated for antimicrobial activities by agar antagonism tests and for proteolytic activity on milk proteins by cultivation on agar plates. The most proteolytic isolates were also tested by cultivation in skim milk followed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the fermented milk. Among the 815 tested isolates, three of them identified as Streptococcus uberis (strains FT86, FT126 and FT190) were bacteriocin producers, whereas four other ones identified as Weissella confusa FT424, W. hellenica FT476, Leuconostoc citreum FT671 and Lactobacillus plantarum FT723 showed high antifungal activity in preliminary assays. Complementary analyses showed that the most antifungal strain was L. plantarum FT723 that inhibited Penicillium expansum in modified MRS agar (De Man, Rogosa, Sharpe, without acetate) and fermented milk model, however no inhibition was observed against Yarrowia lipolytica. The proteolytic capacities of three highly proteolytic isolates identified as Enterococcus faecalis (strains FT132 and FT522) and Lactobacillus paracasei FT700 were confirmed by SDS-PAGE, as visualized by the digestion of caseins and whey proteins (β-lactoglobulin and α-lactalbumin). These results suggest potential applications of these isolates or their activities (proteolytic activity or production of antimicrobials) in dairy foods production.
36 citations
TL;DR: Factor and cluster analyses indicated the unique community structure, on species, genera, class and phyla levels, of the culturable population recovered with plant-based culture media, being distinct from that obtained with the chemically-synthetic culture media.
TL;DR: The results indicate CSAs integrated into Petri dish lids present a novel paradigm to speciate microorganisms, well-suited to integration into automated plate handling systems.
Abstract: Clinical microbiology automation is currently limited by the lack of an in-plate culture identification system. Using an inexpensive, printed, disposable colorimetric sensor array (CSA) responsive to the volatiles emitted into plate headspace by microorganisms during growth, we report here that not only the presence but the species of bacteria growing in plate was identified before colonies are visible. In 1894 trials, 15 pathogenic bacterial species cultured on blood agar were identified with 91.0% sensitivity and 99.4% specificity within 3 hours of detection. The results indicate CSAs integrated into Petri dish lids present a novel paradigm to speciate microorganisms, well-suited to integration into automated plate handling systems.
TL;DR: Routine microbiological examination of patients with corneal ulcer is necessary in order to analyze and compare the changing trends of the etiology and their susceptibility patterns.
Abstract: Purpose: To identify the prevalence and microbial profile of infectious keratitis in a tertiary eye care hospital, and to test for the in vitro antimicrobial resistance of the bacterial isolates. Methods: A total of 312 patients presenting to a tertiary eye care hospital with infected corneal ulcer were enrolled in this study. Their socio-demographic data and risk factors were recorded. Corneal scrapings collected from the edge of the ulcer were processed for direct gram stain and KOH mount. Culture was recovered on blood agar, chocolate agar, MacConkey agar and Sabouraud's dextrose (SDA) agar in multiple C shaped streaks. After overnight incubation, bacterial culture was followed by standard biochemical tests and antimicrobial sensitivity according to the clinical and laboratory standards institute (CLSI) guidelines. Inoculated SDA was inspected daily for up to 10 days and the growth was identified by its colony morphology, pigment production and lacto-phenol cotton blue mount examination. Results: Of 312 patients, a microbial etiology was established in 117 cases (37.5%). Of these, 72 (61.5%) were male. The age range of 41-60 years was the most affected group. Of 117 positive cases, 52 (44.5%) were bacterial, 58 (49.5%) were fungal and 7 (6%) patients showed mixed bacterial and fungal infection. The most common isolated fungus was Fusarium which was detected in 36 (31%) cases, followed by Aspergillus spp in 13 (11%) subjects. Staphylococcus aureus was the most common isolated bacteria. All Gram positive cocci were susceptible to vancomycin followed by gatifloxacin, whereas all Gram negative bacilli were susceptible to gatifloxacin. Conclusion: Routine microbiological examination of patients with corneal ulcer is necessary in order to analyze and compare the changing trends of the etiology and their susceptibility patterns.
TL;DR: A strategy to fabricate whole-hydrogel microfluidic chips using alginate-doped agar makes it possible to prepare inexpensive hydrogel devices, and allows a seamless link betweenmicrofluidics and conventional agar-based cell culture, and could test the synergistic effect of drugs through two-dimensional gradient generation.
Abstract: Antimicrobial resistance (AMR) is a rapidly increasing threat to the effective treatment of infectious diseases worldwide. The two major remedies include: (1) using narrow-spectrum antibiotics based on rapid diagnosis; and (2) developing new antibiotics. A key part of both remedies is the antimicrobial susceptibility test (AST). However, the current standard ASTs that monitor colony formation are costly and time-consuming and the new strategies proposed are not yet practical to be implemented. Herein, we report a strategy to fabricate whole-hydrogel microfluidic chips using alginate-doped agar. This agar-based microfabrication makes it possible to prepare inexpensive hydrogel devices, and allows a seamless link between microfluidics and conventional agar-based cell culture. Different from common microfluidic systems, in our system the cells are cultured on top of the device, similar to normal agar plate culture; on the other hand, the microfluidic channels inside the hydrogel allow precise generation of linear gradient of drugs, thus giving a better performance than the conventional disk diffusion method. Cells in this system are not exposed to any shear flow, which allows the reliable tracking of individual cells and AST results to be obtained within 2–3 hours. Furthermore, our system could test the synergistic effect of drugs through two-dimensional gradient generation. Finally, the platform could be directly implemented to new drug discovery and other applications wherein a fast, cost-efficient method for studying the response of microorganisms upon drug administration is desirable.
TL;DR: High level of suspicion is required to detect SCVs in patients who presented with persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia complicated by surgical site infections after cardiothoracic surgery.
Abstract: The small-colony variant (SCV) phenotype of Staphylococcus aureus is associated with intracellular persistence and reduced antimicrobial susceptibility, which can lead to therapeutic failure. Since SCVs grow slowly and have a confusing morphology, the identification of infections due to SCV is difficult. We have identified SCVs in two patients who presented with persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia complicated by surgical site infections after cardiothoracic surgery. Nine blood isolates were collected from the two patients for species identification, antimicrobial susceptibility testing, and phenotypic and genotypic characterization. Colonies on Columbia blood agar were pinpoint, nonpigmented, nonhemolytic, and reverted to normal colonies after 48 hr of incubation on Schaedler agar. Auxotrophy assays revealed hemin dependence. Susceptibility to vancomycin (minimal inhibitory concentrations 1.0 μg/mL) was confirmed by E-test and broth microdilution test. All the isolates...
TL;DR: This work demonstrated an acceptable feasibility of using gas sensors—a rapid, easy and nondestructive method for predicting P. aeruginosa growth.
Abstract: A rapid method of predicting the growing situation of Pseudomonas aeruginosa is presented. Gas sensors were used to acquire volatile compounds generated by P. aeruginosa on agar plates and meat stuffs. Then, optimal sensors were selected to simulate P. aeruginosa growth using modified Logistic and Gompertz equations by odor changes. The results showed that the responses of S8 or S10 yielded high coefficients of determination (R2) of 0.89–0.99 and low root mean square errors (RMSE) of 0.06–0.17 for P. aeruginosa growth, fitting the models on the agar plate. The responses of S9, S4 and the first principal component of 10 sensors fit well with the growth of P. aeruginosa inoculated in meat stored at 4 °C and 20 °C, with R2 of 0.73–0.96 and RMSE of 0.25–1.38. The correlation coefficients between the fitting models, as measured by electronic nose responses, and the colony counts of P. aeruginosa were high, ranging from 0.882 to 0.996 for both plate and meat samples. Also, gas chromatography–mass spectrometry results indicated the presence of specific volatiles of P. aeruginosa on agar plates. This work demonstrated an acceptable feasibility of using gas sensors—a rapid, easy and nondestructive method for predicting P. aeruginosa growth.
Journal Article•
TL;DR: The results suggest that the MNM-1400 strain can be considered as a potential probiotic in aquaculture, which exhibited highest antagonistic and exoenzymatic activity.
Abstract: The application of new probiotics is a good strategy in the biological control of infectious diseases in aquaculture. Approximately 100 marine actinobacteria isolates were obtained from 10 sediment samples of shrimp farms. Heat treatment of sediment samples resulted in a selective reduction of the non actinobacterial heterotrophic microflora. Starch nitrate agar medium exhibited more efficacy than glycerol arginine agar medium for isolation. Twenty seven percent of actinobacterial isolates showed antagonistic activities against pathogenic Vibrio spp. All the antagonistic isolates showed the typical morphology of genus Streptomyces. Exoenzymatic activity screening showed that 44 %, 26%, 37% of antagonistic isolates represented amylase, lipase and protease activities, respectively. MNM-1400 strain exhibited highest antagonistic and exoenzymatic activity. The pathogenicity experiment revealed that MNM-1400 strain did not cause disease in Litopenaeus vannamei larvae. Extraction of produced antibacterial compounds by MNM-1400 strain showed that the active constituent didn’t have non polar property. Morphological, physiological and biochemical identification confirmed that MNM-1400 strain belonged to the genus streptomyces. Phylogenetic analysis by 16S rRNA gene sequencing showed a high similarity between MNM-1400 strain and Streptomyces californicus (similarity: 99%). These results suggest that the MNM-1400 strain can be considered as a potential probiotic in aquaculture.
TL;DR: Microorganisms that remained at the end of cataract surgery had the capacity to produce biofilm and had high antibiotic resistance, and further studies into prevention of biofilm formation are required.
Abstract: Objective: To evaluate the bacterial flora of corneal wounds at the end of cataract surgery before intracameral antibiotic use and to determine agents to treat postoperative endophthalmitis, the potential for biofilm formation, and antibiotic resistance. Method: This cross-sectional clinical study included patients who underwent cataract surgery using the phacoemulsification technique without any complications. The hemifacial skin, periocular area, eyelids and eyelashes were washed with 10% povidone-iodine and the conjunctiva was washed with 5% povidoneiodine before cataract surgery. After uncomplicated surgery, a wipe sample was taken from the bulbar conjunctival surface, corneal surface, and wound rim before administering intracameral antibiotics. All samples were plated on blood agar, MRS agar, M17 agar, calcium-lactate agar, plate-count agar, and Sabouraud-dextrose agar. Biofilm formation was evaluated by microtitre plates and the Congo red-agar method. Antimicrobial resistance patterns of isolates we...
TL;DR: Safety risks, such as antibiotic resistance and biogenic amine production, are quite common among strains of the species S. carnosus, and each strain should be analysed individually before it is applied as starter culture in meat products.
TL;DR: An improved rapid flow-cytometry based detection method was developed, using a fluorescence-labeled oligonucleotide probe specifically binding a16S rRNA sequence, which positively detected 51 E. coli isolates as well as 4 Shigella species.
Abstract: Standard methods to detect Escherichia coli contamination in food use the polymerase chain reaction (PCR) and agar culture plates. These methods require multiple incubation steps and take a long time to results. An improved rapid flow-cytometry based detection method was developed, using a fluorescence-labeled oligonucleotide probe specifically binding a16S rRNA sequence. The method positively detected 51 E. coli isolates as well as 4 Shigella species. All 27 non-E. coli strains tested gave negative results. Comparison of the new genetic assay with a total plate count (TPC) assay and agar plate counting indicated similar sensitivity, agreement between cytometry cell and colony counts. This method can detect a small number of E.coli cells in the presence of large numbers of other bacteria. This method can be used for rapid, economical, and stable detection of E. coli and Shigella contamination in the food industry and other contexts.
TL;DR: Metabolites of marine derived fungus Eurotium rubrum MPUC136 differed between cultivation on wheat medium and Czapek-Dox agar medium, suggesting that different cultivation processes could affect metabolism and enhance bioactivities.
TL;DR: A culture-based method combining novel chromogenic agar media and appropriate incubation conditions was developed to enumerate lactic acid bacteria (LAB) strains in fermented milk, the first description of a chromogenic culture method applied to selective enumeration of LAB.
TL;DR: NAC has almost equal antimicrobial property as 2% CHX whereas their combination showed a synergistic action, suggesting a synergism action as intracanal medicament.
Abstract: Aim: The purpose of this study was to evaluate the antibacterial efficacies of 2% chlorhexidine (CHX), N-acetyl cysteine (NAC) and assess their synergistic or antagonist action as intracanal medicament. Materials and Methods: Agar diffusion test was performed with 2% CHX, NAC, and their combination against E. faecalis planktonic cells. The diameters of the zones of bacterial inhibition were measured and recorded for each solution. The assay was further extended to 2 weeks old E. faecalis dentinal biofilm. Sixteen freshly extracted teeth were vertically sectioned into two halves resulting in a total of 32 samples. The samples were inoculated with bacterial suspension and incubated at 37°C for 2 weeks for biofilm formation. The samples were then divided into four experimental groups with 8 samples in each group. The samples were gently washed in saline and placed in culture wells containing the test solutions, i.e., 2% CHX, NAC, a combination of 2% CHX and NAC in 1:1 ratio, and a control group containing saline. The biofilm formed on the root canal surface were removed with a sterile scalpel and inoculated on blood agar plates to check for the formation of E. faecalis colonies. Statistical Analysis: For agar diffusion test, data were analyzed statistically using one-way analysis of variance and then by post-hoc Scheffe's test to compare the antimicrobial efficacy between the groups. Statistical analysis was not done for the cultures obtained from the biofilm as there was no growth in all the three test groups except the control group, i.e., saline. Results: In agar diffusion test, among the three groups tested, 2% CHX and NAC showed almost equal zones of inhibition whereas maximum inhibition was shown by a combination of NAC and 2% CHX suggesting a synergistic action. The results obtained were highly significant (P Conclusion: NAC has almost equal antimicrobial property as 2% CHX whereas their combination showed a synergistic action.
TL;DR: It is shown that aggregation during growth in the laboratory standard medium tryptic soy broth (TSB) is common among clinical and laboratory S. aureus isolates and that aggregation may introduce significant bias when applying standard enumeration methods on S.aureus growing in laboratory batch cultures.
TL;DR: It was found that the females were more prone to UTI than males and all antibiotics used in present study except Cotrimoxazole and Nalidixic acid could be the choice for empirical treatment of UTI.
Abstract: Urinary tract infection (UTI) is one of the most common infections of the world caused by mainly Escherichia coli. The purpose of this study was to identify E. coli as causative agent of UTI in patient of different age groups and to investigate their responses against commonly used antibiotics. Altogether, 480 urine samples were analyzed by culture method. The samples were equally streaked on Blood agar, MacConkey, and Eosin Methylene Blue Agar and then incubated at 37oC for 24 hours. After 24 hours of incubation, E. coli was identified on the basis of morphological characteristics of colony on culture media. For further confirmation of the presence of E. coli, Gram staining and conventional biochemical tests were also performed. Disk diffusion method was used for susceptibility testing against seventeen different antibiotics on Muller Hinton agar. Among the 480 urine samples, 81 samples were positive for E. coli. It was found that the females were more prone to UTI than males. The result of antibiotic sensitivity test on E. coli isolates demonstrated that they were highly sensitive to Amikacin, Gentamycin, Netilmycin, Imipenem, Meropenem, Pipracillin-Tazobactam, Tobramycin, Nitrofurantoin , Azithromycin, Levofloxacin, and Ciprofloxacin. E. coli was found intermediate sensitive to third-generation Cephalosporins such as Cefixime, Cefotaxime, Ceftazidime, Ceftriaxone and least sensitive to Cotrimoxazole and Nalidixic acid. Thus, all antibiotics used in present study except Cotrimoxazole and Nalidixic acid, could be the choice for empirical treatment of UTI.
TL;DR: The morphological, cultural, physiological, biochemical and molecular genetic characteristics of the soil streptomycete let to identify it as Streptomyces netropsis (Finlay et al., 1951) IMV Ac-5025 (UCM Ac-2186) that is an active antagonist IMVs Ac- 5025 against plant pathogens.
Abstract: Aim Determination of the taxonomic status of the soil streptomycete Streptomyces sp. 100 and study of its antagonistic properties against phytopathogenic and opportunistic human microorganisms. Methods For the identification of the strain a set of conventional methods morphological and cultural, physiological and biochemical characteristics of the producer, as well as molecular genetic analysis of 16S rRNA gene were used. Streptomycete was cultivated on agar nutrient and liquid soy medium until the stationary phase of growth. The antagonistic activity of the strain was studied by agar diffusion method. Results The study of morphological and cultural properties showed that Streptomyces sp. 100 formed the colonies with irregular edges protruding from the depressed center, straight sporophores were short, gathered in whorls; spores were oval, smooth shell dispute. Growing on agar medium (pH 6.8-7.4, temperature 28 °C, microaerophilic conditions) this strain formed mycelium of various colors: the air white, white-yellow, white-brown or substrate tan, cream and yellow, creamy carmine, yellow-brown. A soluble pigment was yellow and yellow-brown, while melanoid pigment was not detected. The morphological, cultural, physiological, biochemical and molecular genetic characteristics of the soil streptomycete let to identify it as Streptomyces netropsis (Finlay et al., 1951) IMV Ac-5025 (UCM Ac-2186) that is an active antagonist IMV Ac-5025 against plant pathogens. Growing on a surface of agaric nutrient media it inhibits phytopathogenic bacteria (Xanthomonas axonopodis pv. glycines 8609, Pseudomonas savastanoi pv. glycinea 8571, P. syringae pv. coronafaciens 9030) and fungi (Alternaria alternata 16814, Fusarium оxysporum 54201) zone of growth inhibition were 20 - 32 mm and 16 - 30 mm respectively. The supernatant of culture medium and the ethanol extract of biomass inhibited the growth of pathogenic bacteria and fungi. The most sensitive to action of a supernatant of cultural liquid were P. syringae pv. atrofaciens 7886 and Clavibacter michiganensis ssp. michiganensis 102, growth inhibition zones - 42 and 30 mm respectively. It should be noted that in the majority of cases the supernatant of cultural liquid suppressed growth of phytopathogenic bacteria in comparison with biomass extract more actively. At the same time only biomass extract inhibited the growth of P. syringae pv. coronafaciens 9060, P. corrugatа 9070, X. anoxopodis pv. glycines 9075, X. anoxopodis pv. glycines 8609 and Pantoea agglomerans 8490. Tolerant to metabolites of S. netropsis IMV Ac-5025 were P. syringae pv. atrofaciens 8291 and X. visicatoriae 7790. The extract of biomass S. netropsis IMV Ac-5025 inhibited growth of all studied strains of phytopathogenic fungi (A. alternata 16814, A. culmorum 00790, F. оxysporum 54201, F. tricinetum 00795, F. oxysporum n.33, Cladosporium herbarum 16863, Cochliobolus spicifas 16860, Nigrospora oryzae 16864). The supernatant of the cultural liquid also showed the oppressing action on fungi, except for Cladosporium herbarum 16863 and Cochliobolus spicifas 16860. The strain was almost ineffective against opportunistic human microorganisms (Escherichia coli ATCC 25922, Bacillus pumilus NCTC 8241, Staphylococcus aureus FDA 209P et al.). Conclusions The lack of action of Streptomyces netropsis IMV Ac-5025 on the opportunistic human microorganisms and the active antagonism of phytopathogens, both, define potential its application for plant protection.
TL;DR: The use of ZnO nanoparticle in sub-MIC concentration as cover of artificial instruments such as catheter, intravascular catheters or shunts to control bacterial infection is suggested for further study.
Abstract: In this study, the effect of sub-MIC concentrations of the ZnO nanoparticle on the expression of the alpha-hemolysin gene as a significant virulence factor of Staphylococcus aureus is assessed. The effect of sub-MIC concentration (312.5 μg/ml) of the ZnO nanoparticle on the hemolysis phenomenon was studied phenotypically on Blood agar media with and without ZnO nanoparticles and genetically by Real Time PCR method in media containing and without ZnO. The hemolysis phenomena of all S.aureus isolates in a blood agar with a sub-MIC concentration and 1/2, 1/4, and 1/8 MIC concentrations of ZnO nanoparticles was completely restrained. After performing Real Time PCR, the amount of hla gene expression in 12 h culture in media with 1/2 and 1/4 MIC concentration of ZnO nanoparticles was reduced, but gene expression in the 1/8 MIC concentration was did not decrease. Hemolysis by S. aureus was decreased in the presence sub-MIC concentration of ZnO nanoparticles. The use of ZnO nanoparticle in sub-MIC concentration as cover of artificial instruments such as catheter, intravascular catheters or shunts to control bacterial infection is suggested for further study.
TL;DR: It is concluded that skin wound irrigation with tap water leads to further reduction of Gram‐positive bacteria compared with 0·9% sodium chloride sterile solution, with no difference in colonisation of haemolytic bacteria, Gram‐negative bacteria and fungi.
Abstract: Irrigating wounds with tap water does not increase colonisation, but controlled studies are required for further evidence. Microbial colonisation was assessed in skin wounds, before and after irrigation with tap water, and was compared with irrigation using 0·9% sodium chloride sterile solution. The study included 120 subjects with chronic, traumatic, vascular, pressure or neuropathic wounds. A total of 60 wounds were randomly assigned to be irrigated with tap water (tap water group) and another 60 to be irrigated with 0·9% sodium chloride sterile solution (saline group), at a pressure of 0·46-0·54 PSI. Samples were collected from the centre of each wound using Levine's technique, before and after irrigation, and cultivated in thioglycollate, hypertonic mannitol agar, eosin methylene blue (EMB) agar, blood agar and Sabouraud agar at 37°C for 72 hours. There was concordance (kappa test) and discordance (McNemar test) regarding the count of positive and/or negative samples before and after irrigation in each group. The proportion of reduction of positive samples was similar for both groups in all cultures. Colony-forming unit count before and after irrigation was similar in both groups and in all cultures, except for the culture in hypertonic mannitol agar from the tap water group, for which the count was lower after irrigation (Wilcoxon z = 2·05, P = 0·041). It is concluded that skin wound irrigation with tap water leads to further reduction of Gram-positive bacteria compared with 0·9% sodium chloride sterile solution, with no difference in colonisation of haemolytic bacteria, Gram-negative bacteria and fungi.
TL;DR: It is suggested that CHROMagar STEC performs better than Possé or SHIBAM for detection of STEC in bovine feces, but adjustments in the concentrations of novobiocin and potassium tellurite in the latter two media result in significant improvements in their performance.
TL;DR: This study reaffirms the need for both liquid medium and solid medium for mycobacterial and aerobic actinomycetes culture and demonstrates that solid medium incubation times may be reduced to 6 weeks without significantly impacting sensitivity.
Abstract: Mycobacterial cultures are historically performed using a liquid medium and a solid agar medium with an incubation period of up to 60 days. We performed a retrospective analysis of 21,494 mycobacterial and aerobic actinomycetes cultures performed over 10 months to determine whether two medium types remain necessary and to investigate whether culture incubation length can be shortened. Specimens were cultured using Bactec MGIT liquid medium and Middlebrook 7H11/S7H11 solid medium with incubation periods of 42 and 60 days, respectively. Time-to-positivity and the identity of isolates recovered from each medium were evaluated. A total of 1,205/21,494 cultures (6%) were positive on at least one medium. Of the 1,353 isolates recovered, 1,110 (82%) were nontuberculous mycobacteria, 145 (11%) were aerobic actinomycetes, and 98 (7%) were Mycobacterium tuberculosis complex. Assessing medium types, 1,121 isolates were recovered from solid medium cultures, 922 isolates were recovered from liquid medium cultures, and 690 isolates were recovered on both media. Liquid cultures were positive an average of 10 days before solid cultures when the two medium types were positive ( P