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.

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 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.

scholarly journals Formation in vitro of colistin resistance in carbapenem-resistant Gram-negative bacteria and its biological cost

2021 ◽  
Author(s):  
D. V. Tapalski ◽  
T. A. Petrovskaya ◽  
A. E. Kozlov
Keyword(s):  
Broth Culture ◽  
Exponential Growth Phase ◽  
Lag Phase ◽  
Gram Negative Bacteria ◽  
Colistin Resistance ◽  
Gram Negative ◽  
Broth Microdilution Method ◽  
Resistant Mutants ◽  
Biological Cost

Introduction. The spread of resistance to carbapenems among gram-negative bacteria have led to an increase in the consumption of polymyxins and the emergence of certain strains resistant to them. Polymyxin resistance is mainly associated with mutations in chromosomal genes. The development of mutational resistance to antibiotics can lead to a decrease in the viability of bacteria, which is manifested by an increase in the duration of the cell cycle, a decrease in virulence and competitive fitness. The purpose of the study was to assess in vitro the intensity of the formation of colistin resistance in carbapenemresistant clinical isolates of gram-negative bacteria, the stability of the formed emerged resistance and its biological cost.Materials and methods. For 46 strains of Klebsiella pneumoniae, 77 strains of Pseudomonas aeruginosa and 42 strains of Acinetobacter baumannii, real time polymerase chain reaction (PCR) was used to detect the genes of carbapenemases, the minimum inhibitory concentrations (MIC) of meropenem and colistin were determined by broth microdilution method. The selection of resistant subpopulations on Muller–Hinton agar with the addition of 16 mg/l colistin was carried out. For colistin-resistant mutants and their isogenic sensitive strains, the kinetic parameters of growth in broth culture were determined. Incubation and result recording were performed on an Infinite M200 microplate reader for 18.5 hours at 35°C with measurement of light scatter in the wells every 15 minutes.Results. The production of carbapenemases MBL VIM in P. aeruginosa, MBL NDM, KPC and OXA-48 in K. pneumoniae, OXA-23 and OXA-40 in A. baumannii was observed. All strains were sensitive to colistin (MIC varied from 0.062 to 2 mg/l). The colony growth on a selective medium with16 mg/l colistin was observed for 97.8% of K. pneumoniae strains, 16.9% of P. aeruginosa strains, and 61.9% of A. baumannii strains. The mutational nature of colistin resistance was confirmed for 21.7% of K. pneumoniae strains. For colistin-resistant mutants of K. pneumoniae, a significant increase in the duration of the lag phase (Tlag) was observed: 225.6 ± 7.037 min in the wild-type susceptible strains and 245.5 ± 8.726 in resistant mutants, p = 0.037. The indicators of the doubling time of the number of microbial cells in the exponential growth phase (Tdoubling) and the area under the bacterial growth curve did not differ significantly.Conclusion. A high frequency of formation of colistin resistance in vitro in carbapenemase-producing strains of K. pneumoniae was observed. The absence of significant changes in the kinetics of microbial growth in resistant strains makes it possible to predict the further spread of mutational resistance to colistin, as well as its preservation in microbial populations of K. pneumoniae even in the case of limiting the use of this antibiotic. 

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.

Label-Free Rapid Detection of Pathogens with Antimicrobial Peptide Assisted Impedance Spectrometry

2015 ◽  
Vol 1793 ◽  
pp. 13-18 ◽  
Author(s):  
Keren Jiang ◽  
Hashem Etayash ◽  
Sarfuddin Azmi ◽  
Garima Thakur ◽  
Selvaraj Naicker ◽  
...  
Keyword(s):  
Rapid Detection ◽  
Dynamic Range ◽  
Detection Method ◽  
Detection Methods ◽  
Handheld Devices ◽  
Gram Negative Bacteria ◽  
Label Free ◽  
Gram Positive ◽  
Gram Negative ◽  
Impedance Sensor

ABSTRACTAn urgent need exist for developing handheld devices for rapid, sensitive, and specific detection method for pathogens. Here we demonstrate a rapid detection method for Gram-positive and Gram-negative bacteria using an impedance sensor array functionalized with antimicrobial peptides (AMPs). This impedance sensor screens pathogens in real-time and has comparable sensitivity with current detection methods like polymerase chain reaction (PCR) and immunoassay. Functionalized electrodes in array selectively bind to the corresponding bacteria strains, resulting in variations in the impedance modulus. Impedance variation is used to detect incubated bacterial cell concentration with a resolution of 1 cell µL-1. The dynamic range of detection for both Gram-positive and Gram-negative bacteria is found to be 103-106cfu mL-1. Micropatterned electrodes modified with AMPs in an impedimetric array offer an excellent platform for rapid and selective detection of pathogens in contaminated water and food products.

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.

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