scholarly journals The Anti-Staphylococcal Potential of Ethanolic Polish Propolis Extracts

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1732 ◽  
Author(s):  
Katarzyna Grecka ◽  
Piotr M. Kuś ◽  
Piotr Okińczyc ◽  
Randy W. Worobo ◽  
Justyna Walkusz ◽  
...  
Keyword(s):  
Hplc Analysis ◽  
Bactericidal Effect ◽  
Gram Negative Bacteria ◽  
Broth Microdilution ◽  
Inhibit Protein Synthesis ◽  
Gram Negative ◽  
E Coli ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Ethanol Extracts

The principal objective of this study was to determine the anti-staphylococcal potential of ethanol extracts of propolis (EEPs). A total of 20 samples of propolis collected from apiaries located in different regions of Poland were used in the study. The two-fold broth microdilution method revealed some important differences in the antimicrobial activity of investigated EEPs. Up to the concentration of 4096 µg/mL no activity was observed against Gram-negative bacteria (E. coli and P. aeruginosa). Staphylococci exhibited much higher susceptibility. The highest efficiency observed for EEP12 and EEP20 (MIC values ranged between 32 and 256 µg/mL). However, the achievement of bactericidal effect usually required higher concentrations. In the case of clinical isolates of S. aureus MBC values for EEP12 and EEP20 ranged from 512 to 1024 µg/mL. The HPLC analysis revealed that these two products contained a higher concentration of flavonoids (flavonols, flavones, and flavanones) compared to other investigated EEPs. In checkerboard test, a synergistic anti-staphylococcal effect was observed for the action of EEP20 in combination with amikacin, kanamycin, gentamycin, tetracycline, and fusidic acid (all these antibiotics inhibit protein synthesis). Moreover, the investigated EEPs effectively eradicated staphylococcal biofilm. The obtained results clearly confirm the high anti-staphylococcal potential of propolis harvested in Polish apiaries.

Chemical composition and antimicrobial activity of Erodium species: E. ciconium L., E. cicutarium L., and E. absinthoides Willd. (Geraniaceae)

2010 ◽  
Vol 64 (3) ◽  
Author(s):  
Zorica Stojanović-Radić ◽  
Ljiljana Čomić ◽  
Niko Radulović ◽  
Milan Dekić ◽  
Vladimir Ranđelović ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Chemical Composition ◽  
Essential Oils ◽  
Palmitic Acid ◽  
Gram Negative Bacteria ◽  
Broth Microdilution ◽  
Bacterial Strains ◽  
Gram Negative ◽  
Microdilution Method ◽  
Broth Microdilution Method

AbstractThe present study gives results of chemical composition analyses and antimicrobial activity testing of three Erodium species: E. ciconium L., E. cicutarium L., and E. absinthoides Willd. Essential oils were obtained by hydro-distillation from air-dried entire plants and analyzed by GC and GC-MS. A total of 209 different compounds were identified: 162 for E. cicutarium, 107 for E. ciconium, and 79 for E. absinthoides. Antimicrobial activity (broth microdilution method) of the oils was screened against a panel of Gram positive and Gram negative bacteria and a number of fungi. Moderate susceptibility of all tested strains was observed. Determined MIC values were 0.156–5 mg mL−1 (bacterial strains) and 0.039–0.325 mg mL−1 (fungal strains). Major component of the most active oil, palmitic acid, was also tested for activity together with stearic and myristic acids.

scholarly journals Evaluation of resazurin-based assay for rapid detection of polymyxin-resistant gram-negative bacteria

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Huaiyu Jia ◽  
Renchi Fang ◽  
Jie Lin ◽  
Xuebin Tian ◽  
Yajie Zhao ◽  
...  
Keyword(s):  
Rapid Detection ◽  
Visual Detection ◽  
Detection Method ◽  
Gram Negative Bacteria ◽  
Broth Microdilution ◽  
Colistin Resistance ◽  
Acinetobacter Baumanii ◽  
Gram Negative ◽  
Microdilution Method ◽  
Broth Microdilution Method

Abstract Background Colistin resistance is considered a serious problem due to a lack of alternative antibiotics. The Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test is a resazurin reduction-based technique that relies on the visual detection of bacterial growth in the presence of a defined concentration of colistin. The aim of this study was to evaluate the performance of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test in the detection of colistin susceptibility in common clinical Gram-negative bacteria. Results A total of 253 clinical isolates from a teaching hospital, including Acinetobacter baumanii (n = 58, 8 colistin-resistant), Pseudomonas aeruginosa (n = 61, 11 colistin-resistant), Klebsiella pneumoniae (n = 70, 20 colistin-resistant) and Escherichia coli (n = 64, 14 colistin-resistant) were tested in this study. The sensitivity and specificity of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test compared to Broth microdilution method was 100 and 99%, respectively. Conclusions Our results suggest that Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test could be used as an accurate detection method for colistin resistance.

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 Evaluation of a Scanner-Assisted Colorimetric MIC Method for Susceptibility Testing of Gram-Negative Fermentative Bacteria

2004 ◽  
Vol 70 (4) ◽  
pp. 2398-2403 ◽  
Author(s):  
Mokhlasur Rahman ◽  
Inger Kühn ◽  
Motiur Rahman ◽  
Barbro Olsson-Liljequist ◽  
Roland Möllby
Keyword(s):  
Bacterial Growth ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
National Committee ◽  
Broth Microdilution ◽  
Gram Negative ◽  
Microdilution Method ◽  
Epidemiological Surveys ◽  
Fermentative Bacteria ◽  
Broth Microdilution Method

ABSTRACT We describe the ScanMIC method, a colorimetric MIC method for susceptibility testing of gram-negative fermentative bacteria. The method is a slight modification of the National Committee for Clinical Laboratory Standards (NCCLS) recommended broth microdilution method that uses a redox indicator 2,3,5-triphenyltetrazolium chloride (TTC) to enhance the estimate of bacterial growth inhibition in a microplate and a flatbed scanner to capture the microplate image. In-house software was developed to transform the microplate image into numerical values based on the amount of bacterial growth and to generate the MICs automatically. The choice of indicator was based on its low toxicity and ease of reading by scanner. We compared the ScanMIC method to the NCCLS recommended broth microdilution method with 197 coliform strains against seven antibacterial agents. The interpretative categorical agreement was obtained in 92.4% of the assays, and the agreement for MIC differences (within ±1 log2 dilution) was obtained in 96% for ScanMIC versus broth microdilution and 97% for a two-step incubation colorimetric broth microdilution versus the broth microdilution method. The method was found to be labor-saving, not to require any initial investment, and to show reliable results. Thus, the ScanMIC method could be useful for epidemiological surveys that include susceptibility testing of bacteria.

scholarly journals Antimicrobial and modulation effects of selected Ghanaian medicinal plants

2017 ◽  
Vol 36 (3) ◽  
pp. 1-7
Author(s):  
E. Ekuadzi ◽  
R. A. Dickson ◽  
T. C. Fleischer ◽  
S. O. Dapaah ◽  
E. O. Reynolds ◽  
...  
Keyword(s):  
Medicinal Plants ◽  
Plant Extracts ◽  
Antimicrobial Agents ◽  
Multidrug Resistant ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Checkerboard Assay ◽  
Ethanol Extracts ◽  
Antibiotic Discovery

The alarming rise in the incidences of multidrug-resistant microorganisms and the decline innew antibiotic discovery make the search for new antimicrobial agents or efforts at restoring the activity of older antibiotics to which the microbes have developed resistance very necessary. The aim of the present study is to investigate the antimicrobial and modulation effects of the 70% ethanol extracts of Lannea schimperi, Commelina nudiflora and Piliostigma reticulatum against usceptible strains of microorganisms. Using the broth microdilution method, the minimum inhibitory concentrations (MICs) of the extracts were determined. The checkerboard assay was used to determine the modulation effects when sub-inhibitory concentrations of plant extracts were combined with the standard antibiotics. All three plants extracts possessed weak antimicrobial effects. For the modulation experiments, fifteen of the twenty-seven combinatorial casesyielded biologically significant effects. The ethanol extracts of the three plants studied here are good modulators as they reduced the MIC of ciprofloxacin and ketoconazole by factors that are comparable to that of reserpine. However the exact compounds and their exact mechanism of modulation require further investigation.Keywords: Anti-infective, modulation, Lannea schimperi, Commelina nudiflora, Piliostigmareticulatum, ethnomedicine

Tentative epidemiologic cut-off value and resistant characteristic detection of apramycin against Escherichia coli from chickens

2019 ◽  
Vol 366 (16) ◽  
Author(s):  
Erjie Tian ◽  
Ishfaq Muhammad ◽  
Wanjun Hu ◽  
Zhiyong Wu ◽  
Rui Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Drug Resistance ◽  
Multiple Drug Resistance ◽  
Aminoglycoside Antibiotic ◽  
Multiple Drug ◽  
Broth Microdilution ◽  
E Coli ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Resistant Strains

ABSTRACT Escherichia coli are important foodborne zoonotic pathogens. Apramycin is a key aminoglycoside antibiotic used by veterinarians against E. coli. This study was conducted to establish the epidemiological cut-off value (ECV) and resistant characteristics of apramycin against E. coli. In this study, 1412 clinical isolates of E. coli from chickens in China were characterized. Minimum inhibitory concentrations (MICs) of apramycin were assessed by broth microdilution method. MIC50 and MIC90 for apramycin against E. coli (0.5–256 µg/mL) were 8 and 16 µg/mL, respectively. In this study, the tentative ECV was determined to be 16 µg/mL by the statistical method and 32 µg/mL by ECOFFinder software. Besides, the percentages of aac(3)-IV positive strains ascended with the increase of MIC values of apramycin, and the gene npmA was detected in strains with higher MICs. Sixteen apramycin highly resistant strains displayed multiple drug resistance (100%) to amoxicillin, ampicillin, gentamicin, doxycycline, tetracycline, trimethoprim and florfenicol, while most of them were susceptible to amikacin and spectinomycin. In summary, the tentative ECV of apramycin against E. coli was recommended to be 16 µg/mL.

scholarly journals Susceptibility to antibiotic combinations of Klebsiella pneumoniae and Acinetobacter baumannii strains isolated from COVID-19 patients

2021 ◽  
Vol 18 (4) ◽  
pp. 33-40
Author(s):  
D. V. Tapalski ◽  
E. V. Karpova
Keyword(s):  
Klebsiella Pneumoniae ◽  
Bactericidal Activity ◽  
Antibacterial Effect ◽  
Bactericidal Effect ◽  
Bacteriostatic Activity ◽  
Broth Microdilution ◽  
Colistin Resistance ◽  
Microdilution Method ◽  
Carbapenem Resistant ◽  
Broth Microdilution Method

Objective. To assess the susceptibility of K.pneumoniae and A.baumanii strains isolated from hospitalized COVID-19 patients to antibiotics and their combinations.Materials and methods. The minimum inhibitory concentrations (MICs) of meropenem and colistin were determined for 47 A.baumannii and 51K.pneumoniaestrains isolated from the hospitalized COVID-19 patients by the broth microdilution method. The susceptibility to 11 antibiotic combinations was assessed using the method of multiple combination bactericidal testing.Results. Colistin resistance was detected in 31.9 % of A.baumannii strains (MIC50 — 0.5 mg/l, MIC90 — 16 mg/l) and in 80.4 % of K.pneumoniaestrains (MIC50 — 16 mg/l, MIC90 — 256 mg/l). It has been shown that double antibiotic combinations with the inclusion of colistin exhibit bactericidal or bacteriostatic activity against 76.6–87.2 % of A.baumannii strains. Combinations with the addition of meropenem, colistin and macrolides exhibited bactericidal activity against 78.4–80.4 % of K.pneumoniae strains. Combinations of two carbapenems were not active, the combination of meropenem-colistin had a bactericidal effect only in 13.7 % of K.pneumoniae strains.Conclusion. Widespread colistin resistance was found in carbapenem-resistant K.pneumoniae and A.baumannii strains isolated from the hospitalized COVID-19 patients. The combinations of antibiotics that have a synergistic antibacterial effect in their pharmacokinetic/pharmacodynamic concentrations have been determined.

Antimicrobial activity of POL7306 tested against clinical isolates of Gram-negative bacteria collected worldwide

2020 ◽  
Vol 75 (6) ◽  
pp. 1518-1524 ◽  
Author(s):  
Helio S Sader ◽  
Paul R Rhomberg ◽  
Leonard R Duncan ◽  
Hans H Locher ◽  
Glenn E Dale ◽  
...  
Keyword(s):  
Protein Targeting ◽  
Treatment Options ◽  
Asia Pacific ◽  
Surveillance Program ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Usa

Abstract Background POL7306 belongs to a new class of peptidomimetic outer-membrane-protein-targeting antibiotics with a novel mechanism of action. POL7306 is in development for the treatment of infections caused by antimicrobial-resistant Gram-negative bacteria and has demonstrated low cytotoxicity and nephrotoxicity. Methods A total of 891 isolates were collected by the SENTRY Antimicrobial Surveillance Program from 134 medical centres in Europe (n = 424; 41 centres in 18 nations), the USA (n = 411 isolates from 67 centres), the Asia-Pacific region (n = 24; 15 centres in 6 nations) and Latin America (n = 32; 11 centres in 9 nations) and included 558 Enterobacterales, 310 non-fermenters and 23 fastidious organisms. Susceptibility testing was performed using the reference broth microdilution method and the medium was supplemented with 0.002% polysorbate-80 for testing POL7306. Resistant subsets were characterized by WGS. Results POL7306 demonstrated potent in vitro activity against Enterobacterales [including carbapenem-resistant (MIC50/90, 0.06/0.25 mg/L), ESBL-producing (MIC50/90, 0.06/0.12 mg/L), KPC-producing (MIC50/90, 0.12/0.25 mg/L), MBL-producing (MIC50/90, 0.06/0.25 mg/L), colistin-non-susceptible, mcr-negative (MIC50/90, 0.5/2 mg/L) and mcr-positive (MIC50/90, 0.12/0.25 mg/L) Enterobacterales], Pseudomonas aeruginosa (MIC50/90, 0.25/0.25 mg/L), Acinetobacter baumannii (MIC50/90, 0.06/0.12 mg/L) and Stenotrophomonas maltophilia (MIC50/90, 0.06/0.25 mg/L). Conclusions POL7306 demonstrated potent activity against a large collection of Gram-negative organisms collected worldwide that included colistin-resistant, XDR and ESBL- and carbapenemase-producing isolates for which there are currently limited treatment options.

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