scholarly journals Isolation, antimicrobial activity of myxobacterial crude extracts and identification of the most potent strains

2017 ◽  
Vol 69 (3) ◽  
pp. 561-568
Author(s):  
Ivana Charousová ◽  
Juraj Medo ◽  
Soňa Javoreková
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Agents ◽  
Sequence Similarity ◽  
Multidrug Resistant ◽  
Antimicrobial Activities ◽  
Gram Positive ◽  
Gram Negative ◽  
Microdilution Method ◽  
Crude Extracts ◽  
Broth Microdilution Method

Broad spectrum antimicrobial agents are urgently needed to fight frequently occurring multidrug-resistant pathogens. Myxobacteria have been regarded as ?microbe factories? for active secondary metabolites, and therefore, this study was performed to isolate two bacteriolytic genera of myxobacteria, Myxococcus sp. and Corallococcus sp., from 10 soil/sand samples using two conventional methods followed by purification with the aim of determining the antimicrobial activity of methanol extracts against 11 test microorganisms (four Gram-positive, four Gram-negative, two yeasts and one fungus). Out of thirty-nine directly observed strains, 23 were purified and analyzed for antimicrobial activities. Based on the broth microdilution method, a total of 19 crude extracts showed antimicrobial activity. The range of inhibited wells was more important in the case of anti-Gram-positive-bacterial activity in comparison with the anti-Gram-negative-bacterial and antifungal activity. In light of the established degree and range of antimicrobial activity, two of the most active isolates (BNEM1 and SFEC2) were selected for further characterization. Morphological parameters and a sequence similarity search by BLAST revealed that they showed 99% sequence similarity to Myxococcus xanthus ? BNEM1 (accession no. KX669224) and Corallococcus coralloides - SFEC2 (accession no. KX669225). As these isolates had antimicrobial activity, they could be considered for use in the development of antibiotics for pharmaceutical use.

scholarly journals In VitroActivity of Plazomicin against Gram-Negative and Gram-Positive Bacterial Pathogens Isolated from Patients in Canadian Hospitals from 2013 to 2017 as Part of the CANWARD Surveillance Study

2018 ◽  
Vol 63 (1) ◽  
Author(s):  
Andrew Walkty ◽  
James A. Karlowsky ◽  
Melanie R. Baxter ◽  
Heather J. Adam ◽  
George G. Zhanel
Keyword(s):  
Antimicrobial Agents ◽  
Bacterial Pathogens ◽  
Multidrug Resistant ◽  
Surveillance Study ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Microdilution Method ◽  
Broth Microdilution Method

ABSTRACTThe Clinical and Laboratory Standards Institute (CLSI) broth microdilution method was used to evaluate thein vitroactivities of plazomicin and comparator antimicrobial agents against 7,712 Gram-negative and 4,481 Gram-positive bacterial pathogens obtained from 2013 to 2017 from patients in Canadian hospitals as part of the CANWARD Surveillance Study. Plazomicin demonstrated potentin vitroactivity againstEnterobacteriaceae(MIC90≤ 1 µg/ml for all species tested exceptProteus mirabilisandMorganella morganii), including aminoglycoside-nonsusceptible, extended-spectrum β-lactamase (ESBL)-positive, and multidrug-resistant (MDR) isolates. Plazomicin was equally active against methicillin-susceptible and methicillin-resistant isolates ofStaphylococcus aureus.

scholarly journals Design, Synthesis, and Evaluation of Novel 3-, 4-substituted, and 3,4-di Substituted Quinazoline Derivatives as Antimicrobial Agents

2020 ◽  
Vol 71 (2) ◽  
pp. 422-435
Author(s):  
Farag A. El-Essawy ◽  
Abdulrahman I. Alharthi ◽  
Mshari A. Alotaibi ◽  
Nancy E. Wahba ◽  
Nader M. Boshta
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Agents ◽  
Antimicrobial Activities ◽  
Bacterial Strains ◽  
Gram Positive ◽  
Design Synthesis ◽  
Gram Negative ◽  
Spectroscopic Analyses ◽  
Quinazoline Derivatives

A novel series of 3-, 4-substituted, and 3,4-di substituted quinazoline derivatives were prepared via various cyclized regents and most of the newly prepared compounds evaluated for their antimicrobial activities in vitro against Gram-positive, Gram-negative bacterial strains and fungi strains. The structures of the quinazoline derivatives have been confirmed using spectroscopic analyses (IR, NMR, and EI-MS). Some of the synthesized derivatives displayed a moderate antimicrobial activity in comparison with reference drugs, for example compounds 13d, 15a, 17b, 18b, 18d, 25, and 29a-c. Among the synthesized compounds, the pyrimidoqunazoline derivative 6c elicited the highest activity.

scholarly journals In Vitro Activity of WCK 5222 (Cefepime-Zidebactam) against Worldwide Collected Gram-Negative Bacilli Not Susceptible to Carbapenems

2020 ◽  
Vol 64 (12) ◽  
Author(s):  
James A. Karlowsky ◽  
Meredith A. Hackel ◽  
Samuel K. Bouchillon ◽  
Daniel F. Sahm
Keyword(s):  
Antimicrobial Agents ◽  
Multidrug Resistant ◽  
Limiting Factor ◽  
Gram Negative ◽  
Content Type ◽  
Microdilution Method ◽  
Carbapenem Resistant ◽  
Broth Microdilution Method ◽  
Universal Stability

ABSTRACT WCK 5222 (cefepime-zidebactam, 2 g + 1g, every 8 h [q8h]) is in clinical development for the treatment of infections caused by carbapenem-resistant and multidrug-resistant (MDR) Gram-negative bacilli. We determined the in vitro susceptibility of 1,385 clinical isolates of non-carbapenem-susceptible Enterobacterales, MDR Pseudomonas aeruginosa (also non-carbapenem susceptible), Stenotrophomonas maltophilia, and Burkholderia spp. collected worldwide (49 countries) from 2014 to 2016 to cefepime-zidebactam (1:1 ratio), ceftazidime-avibactam, imipenem-relebactam, ceftolozane-tazobactam, and colistin using the CLSI broth microdilution method. Cefepime-zidebactam inhibited 98.5% of non-carbapenem-susceptible Enterobacterales (n = 1,018) at ≤8 μg/ml (provisional cefepime-zidebactam-susceptible MIC breakpoint). Against the subset of metallo-β-lactamase (MBL)-positive Enterobacterales (n = 214), cefepime-zidebactam inhibited 94.9% of isolates at ≤8 μg/ml. Further, it inhibited 99.6% of MDR P. aeruginosa (n = 262) isolates at ≤32 μg/ml (proposed cefepime-zidebactam-susceptible pharmacokinetic/pharmacodynamic MIC breakpoint), including all MBL-positive isolates (n = 94). Moreover, cefepime-zidebactam was active against the majority of isolates of Enterobacterales (≥95%) and P. aeruginosa (99%) that were not susceptible to ceftazidime-avibactam, ceftolozane-tazobactam, imipenem-relebactam, and colistin. Most isolates (99%) of S. maltophilia (n = 101; MIC50, 8 μg/ml; MIC90, 32 μg/ml) and Burkholderia spp. (n = 4; MIC range, 16 to 32 μg/ml) were also inhibited by cefepime-zidebactam at ≤32 μg/ml. The activity of cefepime-zidebactam against carbapenem-resistant Gram-negative bacteria is ascribed to its β-lactam enhancer mechanism of action (i.e., zidebactam binding to penicillin binding protein 2 [PBP2] and its universal stability to both serine β-lactamases and MBLs). The results from this study support the continued development of cefepime-zidebactam as a potential therapy for infections caused by Enterobacterales, P. aeruginosa, and other nonfermentative Gram-negative bacilli where resistance to marketed antimicrobial agents is a limiting factor.

scholarly journals In Vitro Activity of Eravacycline against Gram-Negative Bacilli Isolated in Clinical Laboratories Worldwide from 2013 to 2017

2019 ◽  
Vol 64 (3) ◽  
Author(s):  
Ian Morrissey ◽  
Melanie Olesky ◽  
Stephen Hawser ◽  
Sibylle H. Lob ◽  
James A. Karlowsky ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Gram Negative ◽  
Content Type ◽  
Microdilution Method ◽  
Clinical Laboratories ◽  
Serious Infections ◽  
Broth Microdilution Method

ABSTRACT Eravacycline is a novel, fully synthetic fluorocycline antibiotic developed for the treatment of serious infections, including those caused by multidrug-resistant (MDR) pathogens. Here, we evaluated the in vitro activities of eravacycline and comparator antimicrobial agents against a global collection of frequently encountered clinical isolates of Gram-negative bacilli. The CLSI broth microdilution method was used to determine MIC data for isolates of Enterobacterales (n = 13,983), Acinetobacter baumannii (n = 2,097), Pseudomonas aeruginosa (n = 1,647), and Stenotrophomonas maltophilia (n = 1,210) isolated primarily from respiratory, intra-abdominal, and urinary specimens by clinical laboratories in 36 countries from 2013 to 2017. Susceptibilities were interpreted using both CLSI and EUCAST breakpoints. Multidrug-resistant (MDR) isolates were defined by resistance to agents from ≥3 different antimicrobial classes. The MIC90s ranged from 0.25 to 1 μg/ml for Enterobacteriaceae and were 1 μg/ml for A. baumannii and 2 μg/ml for S. maltophilia, Proteus mirabilis, and Serratia marcescens. Eravacycline’s potency was up to 4-fold greater than that of tigecycline against genera/species of Enterobacterales, A. baumannii, and S. maltophilia. The MIC90s for five of six individual genera/species of Enterobacterales and A. baumannii were within 2-fold of the MIC90s for their respective subsets of MDR isolates, while the MDR subpopulation of Klebsiella spp. demonstrated 4-fold higher MIC90s. Eravacycline demonstrated potent in vitro activity against the majority of clinical isolates of Gram-negative bacilli, including MDR isolates, collected over a 5-year period. This study further underscores the potential benefit of eravacycline in the treatment of infections caused by MDR Gram-negative pathogens.

scholarly journals Susceptibility trends of ceftolozane/tazobactam and comparators when tested against European Gram-negative bacterial surveillance isolates collected during 2012–18

2020 ◽  
Vol 75 (10) ◽  
pp. 2907-2913 ◽  
Author(s):  
Helio S Sader ◽  
Cecilia G Carvalhaes ◽  
Leonard R Duncan ◽  
Robert K Flamm ◽  
Dee Shortridge
Keyword(s):  
Eastern Europe ◽  
Active Compound ◽  
Western Europe ◽  
Antimicrobial Agents ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Systemic Infections

Abstract Background The Program to Assess Ceftolozane/Tazobactam Susceptibility (PACTS) monitors the in vitro activity of ceftolozane/tazobactam and numerous antimicrobial agents against Gram-negative bacteria worldwide. Objectives To evaluate the activity of ceftolozane/tazobactam and resistance trends among Pseudomonas aeruginosa and Enterobacterales isolates in Europe between 2012 and 2018. Methods P. aeruginosa (7503) and Enterobacterales (30 582) isolates were collected from 53 medical centres in 26 countries in Europe and the Mediterranean region and tested for susceptibility by reference broth microdilution method in a central laboratory. MIC results were interpreted using EUCAST criteria. Results Ceftolozane/tazobactam was the most active compound tested against P. aeruginosa isolates after colistin, with overall susceptibility rates of 94.1% in Western Europe and 80.9% in Eastern Europe. Moreover, ceftolozane/tazobactam retained activity against 75.2% and 59.2% of meropenem-non-susceptible P. aeruginosa isolates in Western and Eastern Europe, respectively. Tobramycin was the third most active compound tested against P. aeruginosa, with susceptibility rates of 88.6% and 70.9% in Western and Eastern Europe, respectively. Ceftolozane/tazobactam was active against 94.5% of all Enterobacterales and 96.1% of meropenem-susceptible isolates from Western Europe. In Eastern Europe, ceftolozane/tazobactam was active against 79.4% of Enterobacterales overall and 86.2% of meropenem-susceptible isolates. Discussion Antimicrobial susceptibility rates for agents commonly used to treat serious systemic infections varied widely among nations and geographic regions and were generally lower in Eastern Europe compared with Western Europe. Ceftolozane/tazobactam demonstrated potent activity against P. aeruginosa, including MDR strains, and retained activity against most meropenem-susceptible Enterobacterales causing infection in European medical centres.

scholarly journals Antimicrobial Activity of Lignin and Lignin-Derived Cellulose and Chitosan Composites Against Selected Pathogenic and Spoilage Microorganisms

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 670 ◽  
Author(s):  
Alzagameem ◽  
Klein ◽  
Bergs ◽  
Do ◽  
Korte ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Low Temperatures ◽  
Food Packaging ◽  
Antimicrobial Activities ◽  
Gram Negative Bacteria ◽  
Scavenging Activity ◽  
Gram Positive ◽  
Gram Negative ◽  
Spoilage Bacteria ◽  
Chitosan Films

The antiradical and antimicrobial activity of lignin and lignin-based films are both of great interest for applications such as food packaging additives. The polyphenolic structure of lignin in addition to the presence of O-containing functional groups is potentially responsible for these activities. This study used DPPH assays to discuss the antiradical activity of HPMC/lignin and HPMC/lignin/chitosan films. The scavenging activity (SA) of both binary (HPMC/lignin) and ternary (HPMC/lignin/chitosan) systems was affected by the percentage of the added lignin: the 5% addition showed the highest activity and the 30% addition had the lowest. Both scavenging activity and antimicrobial activity are dependent on the biomass source showing the following trend: organosolv of softwood > kraft of softwood > organosolv of grass. Testing the antimicrobial activities of lignins and lignin-containing films showed high antimicrobial activities against Gram-positive and Gram-negative bacteria at 35 °C and at low temperatures (0–7 °C). Purification of kraft lignin has a negative effect on the antimicrobial activity while storage has positive effect. The lignin release in the produced films affected the activity positively and the chitosan addition enhances the activity even more for both Gram-positive and Gram-negative bacteria. Testing the films against spoilage bacteria that grow at low temperatures revealed the activity of the 30% addition on HPMC/L1 film against both B. thermosphacta and P. fluorescens while L5 was active only against B. thermosphacta. In HPMC/lignin/chitosan films, the 5% addition exhibited activity against both B. thermosphacta and P. fluorescens.

scholarly journals In Vitro Activity of Eravacycline against Gram-Positive Bacteria Isolated in Clinical Laboratories Worldwide from 2013 to 2017

2019 ◽  
Vol 64 (3) ◽  
Author(s):  
Ian Morrissey ◽  
Stephen Hawser ◽  
Sibylle H. Lob ◽  
James A. Karlowsky ◽  
Matteo Bassetti ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Clinical Isolates ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Microdilution Method ◽  
Clinical Laboratories ◽  
Broth Microdilution Method ◽  
Doubling Dilution

ABSTRACT Eravacycline is a novel, fully synthetic fluorocycline antibiotic being developed for the treatment of serious infections, including those caused by resistant Gram-positive pathogens. Here, we evaluated the in vitro activities of eravacycline and comparator antimicrobial agents against a recent global collection of frequently encountered clinical isolates of Gram-positive bacteria. The CLSI broth microdilution method was used to determine in vitro MIC data for isolates of Enterococcus spp. (n = 2,807), Staphylococcus spp. (n = 4,331), and Streptococcus spp. (n = 3,373) isolated primarily from respiratory, intra-abdominal, urinary, and skin specimens by clinical laboratories in 37 countries on three continents from 2013 to 2017. Susceptibilities were interpreted using both CLSI and EUCAST breakpoints. There were no substantive differences (a >1-doubling-dilution increase or decrease) in eravacycline MIC90 values for different species/organism groups over time or by region. Eravacycline showed MIC50 and MIC90 results of 0.06 and 0.12 μg/ml, respectively, when tested against Staphylococcus aureus, regardless of methicillin susceptibility. The MIC90 values of eravacycline for Staphylococcus epidermidis and Staphylococcus haemolyticus were equal (0.5 μg/ml). The eravacycline MIC90s for Enterococcus faecalis and Enterococcus faecium were 0.06 μg/ml and were within 1 doubling dilution regardless of the vancomycin susceptibility profile. Eravacycline exhibited MIC90 results of ≤0.06 μg/ml when tested against Streptococcus pneumoniae and beta-hemolytic and viridans group streptococcal isolates. In this surveillance study, eravacycline demonstrated potent in vitro activity against frequently isolated clinical isolates of Gram-positive bacteria (Enterococcus, Staphylococcus, and Streptococcus spp.), including isolates collected over a 5-year period (2013 to 2017), underscoring its potential benefit in the treatment of infections caused by common Gram-positive pathogens.

scholarly journals Correlation between the Antimicrobial Activity and Metabolic Profiles of Cell Free Supernatants and Membrane Vesicles Produced by Lactobacillus reuteri DSM 17938

2020 ◽  
Vol 8 (11) ◽  
pp. 1653
Author(s):  
Alessandro Maccelli ◽  
Simone Carradori ◽  
Valentina Puca ◽  
Francesca Sisto ◽  
Paola Lanuti ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Lactobacillus Reuteri ◽  
Membrane Vesicles ◽  
Metabolic Profiles ◽  
Ion Cyclotron Resonance ◽  
Antimicrobial Compounds ◽  
Ionization Source ◽  
Gram Positive ◽  
Gram Negative ◽  
Broth Microdilution Method

The aim of the work is to assess the antimicrobial activities of Cell Free Supernatants (CFS) and Membrane Vesicles (MVs), produced by Lactobacillus reuteri DSM 17938, versus Gram-positive and Gram-negative bacteria and investigate their metabolic profiles. The Minimum Inhibitory Concentration was determined through the broth microdilution method and cell proliferation assay while the Minimum Bactericidal Concentration was determined by Colony Forming Units counts. The characteristics of the antimicrobial compounds were evaluated by pH adjustments, proteinase treatment, and size fractionation of the CFS. The cytotoxicity of CFS was tested on two human cell lines. A detailed snapshot of the L. reuteri metabolism was attained through an untargeted metabolic profiling by means of high resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) coupled with Electrospray Ionization Source (ESI). The results showed (i) a greater efficacy of CFS and its fractions towards Gram-negative compared to Gram-positive bacteria; (ii) an antimicrobial effect related to pH-dependent compounds but not to MVs; (iii) a molecular weight < 3 KDa as well as an a non-proteinaceous nature of the antimicrobial compounds; and (iv) more than 200 and 500 putative metabolites annotated in MVs and supernatants, covering several classes of metabolites, including amino acids, lipids, fatty and organic acids, polyalcohols, nucleotides, and vitamins. Some putative compounds were proposed not only as characteristic of specific fractions, but also possibly involved in antimicrobial activity.

scholarly journals Synthesis of Plant-Mediated Silver Nanoparticles UsingDioscorea batatasRhizome Extract and Evaluation of Their Antimicrobial Activities

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
P. C. Nagajyothi ◽  
K. D. Lee
Keyword(s):  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Room Temperature ◽  
Antimicrobial Activities ◽  
Gram Positive ◽  
Gram Negative ◽  
Synthesis Of Nanoparticles ◽  
E Coli ◽  
Synthesize Silver Nanoparticles ◽  
Dioscorea Batatas

The eco-friendly synthesis of nanoparticles through various biological means helps to explore various plants for their ability to synthesize silver nanoparticles (AgNPs). Here we have synthesized AgNPs by using rhizome extract ofDioscorea batatasat as well as room temperature (). AgNPs were characterized under UV-vis spectrophotometer, SEM, FTIR, XRD, and EDX. The antimicrobial activity of AgNPs was evaluated on gram positive (B. substilisandS. aureus), gram negative (E. coli), and fungi (S. cerivisaeandC. albicans). At room temperature,S. cerivisaeandC. albicanswere found to be more susceptible to AgNPs than at .

scholarly journals In Vitro Study of Antimicrobial Percutaneous Nephrostomy Catheters for Prevention of Renal Infections

2017 ◽  
Vol 61 (6) ◽  
Author(s):  
Nylev Vargas-Cruz ◽  
Ruth A. Reitzel ◽  
Joel Rosenblatt ◽  
Mohamed Jamal ◽  
Ariel D. Szvalb ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Biofilm Formation ◽  
In Vitro Study ◽  
Percutaneous Nephrostomy ◽  
Multidrug Resistant ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Fungal Organisms

ABSTRACT Percutaneous nephrostomy (PCN) catheters are the primary method for draining ureters obstructed by malignancy and preventing a decline of renal function. However, PCN catheter-related infections, such as pyelonephritis and urosepsis, remain a significant concern. Currently, no antimicrobial PCN catheters are available for preventing infection complications. Vascular catheters impregnated with minocycline-rifampin (M/R) and M/R with chlorhexidine coating (M/R plus CHD) have previously demonstrated antimicrobial activity. Therefore, in this study, we examined whether these combinations could be applied to PCN catheters and effectively inhibit biofilm formation by common uropathogens. An in vitro biofilm colonization model was used to assess the antimicrobial efficacy of M/R and M/R-plus-CHD PCN catheters against nine common multidrug-resistant Gram-positive and Gram-negative uropathogens as well as Candida glabrata and Candida albicans. Experimental catheters were also assessed for durability of antimicrobial activity for up 3 weeks. PCN catheters coated with M/R plus CHD completely inhibited biofilm formation for up to 3 weeks for all the organisms tested. The reduction in colonization compared to uncoated PCN catheters was significant for all Gram-positive, Gram-negative, and fungal organisms (P < 0.05). M/R-plus-CHD PCN catheters also produced significant reductions in biofilm colonization relative to M/R PCN catheters for Enterobacter spp., Escherichia coli, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, C. glabrata, and C. albicans (P < 0.05). M/R-plus-CHD PCN catheters proved to be highly efficacious in preventing biofilm colonization when exposed to multidrug-resistant pathogens common in PCN catheter-associated pyelonephritis. M/R-plus-CHD PCN catheters warrant evaluation in a clinical setting to assess their ability to prevent clinically relevant nephrostomy infections.

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