scholarly journals Approach to Searching for the Producers of Antibiotics That Overcome Drug Resistance of Microorganisms

2021 ◽  
Vol 66 (7-8) ◽  
pp. 4-12
Author(s):  
M. V. Demiankova ◽  
V. S. Sadykova ◽  
A. A. Glukhova ◽  
T. A. Efimenko ◽  
Yu. V. Boykova ◽  
...  
Keyword(s):  
Culture Fluid ◽  
Antibiotic Activity ◽  
Clinical Isolates ◽  
Search Process ◽  
Antimicrobial Compounds ◽  
Negative Bacterium ◽  
Antimicrobial Spectrum ◽  
Chemical Studies ◽  
Natural Strains ◽  
Selection Of

Currently, the problem of antibiotic resistance of opportunistic and pathogenic microorganisms is extremely urgent. In order to find new effective natural antibiotics, it is necessary to intensify the search process. In the gradual selection of the most promising producers, we introduced the stage of determining the antibiotic activity of the culture fluid of the studied natural strains against the clinical isolates of hospital microorganisms with multiple resistance to medical antibiotics. Determining the species affiliation of potential producers allows to select those producers of a particular species that differ in the antimicrobial spectrum of activity from those described in the literature. Four strains of actinomycetes that showed activity against resistant clinical isolates of yeast Candida albicans, C.famata, C.parapsilosis and Cryptococcus neoformans were selected, namely: Nocardia soli INA 01217, Streptomyces bottropensis INA 01214, S.chromofuscus INA 01211 and S.netropsis INA 01190. The N.soli INA 01217 strain also shows antibiotic activity against the Gram-negative bacterium Escherichia coli ATCC 25922. These strains of actinobacterial producers were selected for subsequent chemical studies of the antimicrobial compounds formed by them.

Interdisciplinary Approach for Wellbore Stability During Slimhole Drilling at Volga-Urals Basin Oilfield

2021 ◽  
Author(s):  
Anna Vladimirovna Norkina ◽  
Sergey Mihailovich Karpukhin ◽  
Konstantin Urjevich Ruban ◽  
Yuriy Anatoljevich Petrakov ◽  
Alexey Evgenjevich Sobolev
Keyword(s):  
Drilling Fluid ◽  
Interdisciplinary Approach ◽  
Wellbore Stability ◽  
Vertical Wells ◽  
Wellbore Instability ◽  
Water Based ◽  
Chemical Studies ◽  
Fluid Rheology ◽  
Selection Of

Abstract The design features and the need to use a water-based solution make the task of ensuring trouble-free drilling of vertical wells non-trivial. This work is an example of an interdisciplinary approach to the analysis of the mechanisms of instability of the wellbore. Instability can be caused by a complex of reasons, in this case, standard geomechanical calculations are not enough to solve the problem. Engineering calculations and laboratory chemical studies are integrated into the process of geomechanical modeling. The recommendations developed in all three areas are interdependent and inseparable from each other. To achieve good results, it is necessary to comply with a set of measures at the same time. The key tasks of the project were: determination of drilling density, tripping the pipe conditions, parameters of the drilling fluid rheology, selection of a system for the best inhibition of clay swelling.

scholarly journals Molecular Analysis of the gyrA and gyrB Quinolone Resistance-Determining Regions of Fluoroquinolone-Resistant Clostridium difficile Mutants Selected In Vitro

2009 ◽  
Vol 53 (6) ◽  
pp. 2463-2468 ◽  
Author(s):  
Patrizia Spigaglia ◽  
Fabrizio Barbanti ◽  
Thomas Louie ◽  
Frédéric Barbut ◽  
Paola Mastrantonio
Keyword(s):  
Clostridium Difficile ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Toxin B ◽  
Relevant Role ◽  
Vitro Development ◽  
Selection Of

ABSTRACT Recent studies have suggested that exposure to fluoroquinolones represents a risk factor for the development of Clostridium difficile infections and that the acquisition of resistance to the newer fluoroquinolones is the major reason facilitating wide dissemination. In particular, moxifloxacin (MX) and levofloxacin (LE) have been recently associated with outbreaks caused by the C. difficile toxinotype III/PCR ribotype 027/pulsed-field gel electrophoresis type NAP1 strain. In this study, we evaluated the potential of MX and LE in the in vitro development of fluoroquinolone resistance mediated by GyrA and GyrB alterations. Resistant mutants were obtained from five C. difficile parent strains, susceptible to MX, LE, and gatifloxacin (GA) and belonging to different toxinotypes, by selection in the presence of increasing concentrations of MX and LE. Stable mutants showing substitutions in GyrA and/or GyrB were obtained from the parent strains after selection by both antibiotics. Mutants had MICs ranging from 8 to 128 μg/ml for MX, from 8 to 256 μg/ml for LE, and from 1.5 to ≥32 μg/ml for GA. The frequency of mutation ranged from 3.8 × 10−6 to 6.6 × 10−5 for MX and from 1.0 × 10−6 to 2.4 × 10−5 for LE. In total, six different substitutions in GyrA and five in GyrB were observed in this study. The majority of these substitutions has already been described for clinical isolates or has occurred at positions known to be involved in fluoroquinolone resistance. In particular, the substitution Thr82 to Ile in GyrA, the most common found in resistant C. difficile clinical isolates, was observed after selection with LE, whereas the substitution Asp426 to Val in GyrB, recently described in toxin A-negative/toxin B-positive epidemic strains, was observed after selection with MX. Interestingly, a reduced susceptibility to fluoroquinolones was observed in colonies isolated after the first and second steps of selection by both MX and LE, with no substitution in GyrA or GyrB. The results suggest a relevant role of fluoroquinolones in the emergence and selection of fluoroquinolone-resistant C. difficile strains also in vivo.

Low pH reduces the activity of ceftolozane/tazobactam in human urine, but confirms current breakpoints for urinary tract infections

2019 ◽  
Vol 75 (3) ◽  
pp. 593-599 ◽  
Author(s):  
Alina Karoline Nussbaumer-Pröll ◽  
Sabine Eberl ◽  
Birgit Reiter ◽  
Thomas Stimpfl ◽  
Christoph Dorn ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Urinary Tract Infections ◽  
Human Urine ◽  
Negative Impact ◽  
Low Ph ◽  
Antibiotic Activity ◽  
Clinical Isolates ◽  
Acidic Ph ◽  
Bacterial Strains ◽  
Tract Infections

Abstract Background Acidic pH has been shown to impact the antibiotic activity of non-β-lactams in urine. Objectives To investigate the in vitro activity of ceftolozane/tazobactam compared with meropenem at different pH settings in urine. Methods We determined the MICs for 30 clinical isolates of Escherichia coli, 25 clinical isolates of Klebsiella pneumoniae and 24 clinical isolates of Proteus mirabilis in pooled human urine and standard growth medium at pH 5 and 7. Time–kill curves were produced for one representative clinical isolate of tested bacterial strains in urine at pH 5, 6 and 7 for both antibiotics at concentrations above and below the MIC. HPLC analysis of the stability of ceftolozane/tazobactam and meropenem was performed at different pH values. Results The median MICs of both antibiotics were up to 8-fold higher at pH 5 than at pH 7. Bacterial growth of E. coli was not impacted by pH, while for K. pneumoniae and P. mirabilis low pH slightly reduced growth. Compared with pH 7, pH 5 resulted in a significant decrease in antibiotic activity with a delta of up to 3 log10 bacterial counts after 24 h. Impact of acidic pH was lowest for P. mirabilis; however, this strain metabolically increased the pH during experiments. Stability was not impacted by low pH. Conclusions Acidic pH had a significant negative impact on the activity of ceftolozane/tazobactam and meropenem in urine. Considering concentrations achieved in urine, our results confirm existing breakpoints and do not advocate increasing ceftolozane/tazobactam breakpoints for urinary tract infections.

Optimized Image Retrieval System in Oracle DBMS

2017 ◽  
Vol 8 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Kaouther Zekri ◽  
Amel Grissa Touzi ◽  
Noureddine Ellouze
Keyword(s):  
Image Retrieval ◽  
Retrieval System ◽  
Similarity Criteria ◽  
Search Process ◽  
Textual Information ◽  
Experimental Part ◽  
Content Description ◽  
Image Retrieval System ◽  
Assistance Tool ◽  
Selection Of

In this work, the authors are moving towards the creation of an effective image retrieval system in Oracle DBMS. Several DBMSs have been extensively used to manage the textual information stored with images and CBIR tasks usually rely on specific applications. The separation between the DBMSs and CBIR prevents the optimization of integrated search process based on the connection between the textual and visual content description of image. Moreover, the relevance of image retrieval depends directly on the choice of similarity criteria (color, texture, shape) that can give inaccurate results in case of non-trivial selection of these parameters. The purpose of the authors' approach is to build a CBIR system using advanced and integrated retrieval techniques defined in Oracle DBMS. This approach provides an assistance tool that can guide the user to the appropriate choice of search criteria. The authors present an experimental part that measures the performance of their system, which can help the user to correctly model his query by giving the appropriate retrieval criteria for a database with 800 images.

scholarly journals TMC310911, a Novel Human Immunodeficiency Virus Type 1 Protease Inhibitor, ShowsIn Vitroan Improved Resistance Profile and Higher Genetic Barrier to Resistance Compared with Current Protease Inhibitors

2011 ◽  
Vol 55 (12) ◽  
pp. 5723-5731 ◽  
Author(s):  
Inge Dierynck ◽  
Herwig Van Marck ◽  
Marcia Van Ginderen ◽  
Tim H. M. Jonckers ◽  
Madhavi N. L. Nalam ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Protease Inhibitor ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Clinical Isolates ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Selection Of

ABSTRACTTMC310911 is a novel human immunodeficiency virus type 1 (HIV-1) protease inhibitor (PI) structurally closely related to darunavir (DRV) but with improved virological characteristics. TMC310911 has potent activity against wild-type (WT) HIV-1 (median 50% effective concentration [EC50], 14 nM) and a wide spectrum of recombinant HIV-1 clinical isolates, including multiple-PI-resistant strains with decreased susceptibility to currently approved PIs (fold change [FC] in EC50, >10). For a panel of 2,011 recombinant clinical isolates with decreased susceptibility to at least one of the currently approved PIs, the FC in TMC310911 EC50was ≤4 for 82% of isolates and ≤10 for 96% of isolates. The FC in TMC310911 EC50was ≤4 and ≤10 for 72% and 94% of isolates with decreased susceptibility to DRV, respectively.In vitroresistance selection (IVRS) experiments with WT virus and TMC310911 selected for mutations R41G or R41E, but selection of resistant virus required a longer time than IVRS performed with WT virus and DRV. IVRS performed with r13025, a multiple-PI-resistant recombinant clinical isolate, and TMC310911 selected for mutations L10F, I47V, and L90M (FC in TMC310911 EC50= 16). IVRS performed with r13025 in the presence of DRV required less time and resulted in more PI resistance-associated mutations (V32I, I50V, G73S, L76V, and V82I; FC in DRV EC50= 258). The activity against a comprehensive panel of PI-resistant mutants and the limitedin vitroselection of resistant viruses under drug pressure suggest that TMC310911 represents a potential drug candidate for the management of HIV-1 infection for a broad range of patients, including those with multiple PI resistance.

scholarly journals Characterization of clinical isolates of Pseudomonas aeruginosa heterogeneously resistant to carbapenems

2007 ◽  
Vol 56 (1) ◽  
pp. 66-70 ◽  
Author(s):  
Spyros Pournaras ◽  
Alexandros Ikonomidis ◽  
Antonios Markogiannakis ◽  
Nicholas Spanakis ◽  
Antonios N. Maniatis ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Population Analysis ◽  
Growth Curves ◽  
Clinical Isolates ◽  
Lag Phase ◽  
Carbapenem Resistant ◽  
One Step ◽  
Agar Dilution ◽  
Resistant Mutants ◽  
Selection Of

Fourteen apparently carbapenem-susceptible Pseudomonas aeruginosa clinical isolates that exhibited colonies within the inhibition zone around carbapenem discs were analysed. MICs of carbapenems were determined and the isolates were genotyped by PFGE. Population analysis, one-step selection of carbapenem-resistant mutants and growth curves of progenitors and carbapenem-resistant subpopulations were performed. Agar dilution MICs of imipenem and meropenem ranged from 0.5 to 4 mg l−1 and from 0.25 to 2 mg l−1, respectively. Population analysis confirmed subpopulations that grew in concentrations of up to 18 mg l−1 and 12 mg l−1 of imipenem and meropenem, respectively, at frequencies ranging from 6.9×10−5 to 1.1×10−7, suggesting that they might not be detected by standard agar dilution MIC testing. The minority subpopulations exhibited MICs for imipenem ranging from 10 to 20 mg l−1 and for meropenem from 4 to 14 mg l−1. The one-step 8 mg l−1 selection of imipenem-resistant mutants test showed growth in all isolates at frequencies ranging from 3.8×10−4 to 5.1×10−7. Growth curves revealed a prolonged lag phase and a short exponential phase for the heterogeneous subpopulations compared with their respective native subpopulations. These findings may be indicative that the use of carbapenems can lead to selection of P. aeruginosa resistant subpopulations that subsequently cause infections and result in treatment failure.

scholarly journals Antimicrobial Potential of the Alkalophilic Fungus Sodiomyces alkalinus and Selection of Strains–Producers of New Antimicotic Compound

2021 ◽  
Vol 57 (1) ◽  
pp. 86-93
Author(s):  
A. E. Kuvarina ◽  
M. L. Georgieva ◽  
E. A. Rogozhin ◽  
A. B. Kulko ◽  
I. A. Gavryushina ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Antifungal Activity ◽  
Active Compound ◽  
Structural Features ◽  
Antimicrobial Compounds ◽  
Opportunistic Fungi ◽  
Absorption Ratio ◽  
Antibiotic Compounds ◽  
Selection Of

Abstract The ability of alkalophilic micromycetes of the species Sodiomyces alkalinus to produce antimicrobial compounds was studied. As a result of the determination of the spectrum and yield of antibiotic compounds, a promising producer of the antimycotics Sodiomyces alkalinus was selected from the most active strains 8KS17-10. The producer exhibited antifungal activity against opportunistic fungi, as well as pathogenic clinical isolates of molds and yeasts—pathogens of systemic mycoses. The isolated active compound can be attributed to the group of antimicrobial glycopeptides based on the totality of the identified structural features (molecular weight, absorption ratio at certain wavelengths).

ANALISIS MELODI LAGU ANEUK YATIM CIPTAAN RAFLY KANDE

2021 ◽  
Vol 5 (2) ◽  
Author(s):  
Abdul Rozak ◽  
Haria Nanda Pratama ◽  
Rico Gusmanto
Keyword(s):  
Music Theory ◽  
Descriptive Analysis ◽  
Qualitative Approach ◽  
Western Music ◽  
Material Objects ◽  
Search Process ◽  
Pop Music ◽  
Analysis Method ◽  
Political Upheaval ◽  
Selection Of

Aneuk Yatim is a song created in 1999 by Rafly, has a message and meaning of peace in responding to issues of political upheaval in Aceh, and represents the condition of children in Aceh during the conflict. Through lyrics and melody, Rafly is able to create an atmosphere of sadness that can be felt by the community regarding the conditions and situations during the conflict. The vocals in the song Aneuk Yatim, written by Rafly, have a melodic structure and form consisting of musical ornaments, melodic travel arrangements and scales. This study describes the melody in the song Aneuk Yatim written by Rafly Kande using Western music theory. The purpose of this study is to determine the melody analysis method of pop music in Indonesia in general and regional pop music in particular. The approach taken is a qualitative approach, with descriptive analysis methods, assisted by ethical and emic approaches to facilitate the smoothness of the data search process. The selection of methods and approaches is carried out through documentation, observation, and interviews with participants. The form and structure of the melody in the song Aneuk Yatim, written by Rafly Kande, consists of two parts with a tempo of 60 bpm, each of which is divided into two sentences / periods. The sentences are arranged based on various forms of motifs, each of which has a melody and scale that is repeated in the next period / sentence with a slight change in the melody at the end of the figures (closing phrase). The scale used in this song is the Original Minor and Harmonious Minor, with sequences development techniques, diminished, and augmented. The results of this study are expected to become a reference and reference in the perspective of formal objects and material objects, related to the analysis of the form and structure of the melody, the development of melodic patterns discussed in Western music theory.

scholarly journals In Vitro Activities of Novel Nonfluorinated Quinolones PGE 9262932 and PGE 9509924 against Clinical Isolates of Staphylococcus aureus and Streptococcus pneumoniae with Defined Mutations in DNA Gyrase and Topoisomerase IV

2002 ◽  
Vol 46 (6) ◽  
pp. 1651-1657 ◽  
Author(s):  
Mark E. Jones ◽  
Ian A. Critchley ◽  
James A. Karlowsky ◽  
Renée S. Blosser-Middleton ◽  
Franz-Josef Schmitz ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Dna Gyrase ◽  
Quinolone Resistance ◽  
Clinical Isolates ◽  
Wild Type ◽  
Topoisomerase Iv ◽  
Selection Of

ABSTRACT Two 8-methoxy nonfluorinated quinolones (NFQs), PGE 9262932 and PGE 9509924, were tested against contemporary clinical isolates of Staphylococcus aureus (n = 122) and Streptococcus pneumoniae (n = 69) with genetically defined quinolone resistance-determining regions (QRDRs). For S. aureus isolates with wild-type (WT) sequences at the QRDRs, the NFQs demonstrated activities 4- to 32-fold more potent (MICs at which 90% of isolates are inhibited [MIC90s], 0.03 μg/ml) than those of moxifloxacin (MIC90, 0.12 μg/ml), gatifloxacin (MIC90, 0.25 μg/ml), levofloxacin (MIC90, 0.25 μg/ml), and ciprofloxacin (MIC90, 1 μg/ml). Against S. pneumoniae isolates with WT sequences at gyrA and parC, the NFQs PGE 9262932 (MIC90, 0.03 μg/ml) and PGE 9509924 (MIC90, 0.12 μg/ml) were 8- to 64-fold and 2- to 16-fold more potent, respectively, than moxifloxacin (MIC90, 0.25 μg/ml), gatifloxacin (MIC90, 0.5 μg/ml), levofloxacin (MIC90, 2 μg/ml), and ciprofloxacin (MIC90, 2 μg/ml). The MICs of all agents were elevated for S. aureus isolates with alterations in GyrA (Glu88Lys or Ser84Leu) and GrlA (Ser80Phe) and S. pneumoniae isolates with alterations in GyrA (Ser81Phe or Ser81Tyr) and ParC (Ser79Phe or Lys137Asn). Fluoroquinolone MICs for S. aureus strains with double alterations in GyrA combined with double alterations in GrlA were ≥32 μg/ml, whereas the MICs of the NFQs for strains with these double alterations were 4 to 8 μg/ml. The PGE 9262932 and PGE 9509924 MICs for the S. pneumoniae isolates did not exceed 0.5 and 1 μg/ml, respectively, even for isolates with GyrA (Ser81Phe) and ParC (Ser79Phe) alterations, for which levofloxacin MICs were >16 μg/ml. No difference in the frequency of selection of mutations (<10−8 at four times the MIC) in wild-type or first-step mutant isolates of S. aureus or S. pneumoniae was detected for the two NFQs. On the basis of their in vitro activities, these NFQ agents show potential for the treatment of infections caused by isolates resistant to currently available fluoroquinolones.

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