scholarly journals AGENTS INCREMINATED IN MICROBIA REDUCED HATCHABILITY OF DUCK EMBRYOS II. ANTIMICROBIAL IN-VITRO SENSITIVITY TESTING OF Salmonella emek AND E. coli ISOLATES USING MINIMUM INHIBITORY CONCENTRATION (MIC)

1998 ◽  
Vol 40.1 (79) ◽  
pp. 73-82
2016 ◽  
Vol 5 (04) ◽  
pp. 4512
Author(s):  
Jackie K. Obey ◽  
Anthoney Swamy T* ◽  
Lasiti Timothy ◽  
Makani Rachel

The determination of the antibacterial activity (zone of inhibition) and minimum inhibitory concentration of medicinal plants a crucial step in drug development. In this study, the antibacterial activity and minimum inhibitory concentration of the ethanol extract of Myrsine africana were determined for Escherichia coli, Bacillus cereus, Staphylococcus epidermidis and Streptococcus pneumoniae. The zones of inhibition (mm±S.E) of 500mg/ml of M. africana ethanol extract were 22.00± 0.00 for E. coli,20.33 ±0.33 for B. cereus,25.00± 0.00 for S. epidermidis and 18. 17±0.17 for S. pneumoniae. The minimum inhibitory concentration(MIC) is the minimum dose required to inhibit growth a microorganism. Upon further double dilution of the 500mg/ml of M. africana extract, MIC was obtained for each organism. The MIC for E. coli, B. cereus, S. epidermidis and S. pneumoniae were 7.81mg/ml, 7.81mg/ml, 15.63mg/ml and 15.63mg/ml respectively. Crude extracts are considered active when they inhibit microorganisms with zones of inhibition of 8mm and above. Therefore, this study has shown that the ethanol extract of M. africana can control the growth of the four organisms tested.


2018 ◽  
Vol 20 (87) ◽  
pp. 65-69
Author(s):  
R.A. Peleno

The data of the influence of active substances of anthelmintic and antiprotozoal preparations on the growth of L. casei IMB B-7280 and E. coli 055K59 are provided in the article. Their minimal inhibitory concentrations were determined for these strains of microorganisms and the active substances with which possible simultaneous application of probiotic strain L. casei IMB В-7280 is established. With this aim, the effect on the growth of L. casei IMB B-7280 and E. coli 055K59 and the minimum inhibitory concentration of fenbendazole, levamisole and ivermectin, which are part of the anthelmintic preparations and amprolium, tylosin, sodium sulfadimexone and sodium sulfatyazole, which are active substances of antiprotozoal drugs, were investigated. The determination of the minimum inhibitory concentration of the active substances of antiparasitic agents against these strains of microorganisms was carried out in in vitro experiments by serial dilutions in a dense MRS environment and MPA, and a study of the effect on the growth by diffusion method, followed by measurement of growth retardation zones in millimeters. It is established that among active substances of anthelmintic preparations only phenbendazole caused growth retardation and only relative to L. casei IMB B-7280. Among the active substances of antiprotozoal drugs, sodium sulfatyazole was the most active, which inhibited growth as L. casei IMB-7280 and E. coli 055K59 № 3912/41. Thylosin was effective only in relation to L. casei IMB B-7280 and at the highest concentration of 0.03%, the growth retardation zone was 23.4 ± 0.92 mm. Sodium sulfadimetoxin caused the growth retardation of L. сasei IMB В-7280 only at the highest concentration. The minimum inhibitory concentration of active substances of anti-parasitic drugs was different for strains L. casei IMB B-7280 and E. coli 055K59 № 3912/4. The strongest inhibitory effect was shown by tylosin, which stopped the growth of L. casei IMB B-7280 and E. coli 055K59 № 3912/41 respectively at concentrations of 0.00125 and 50.0 mg/ml. Active substances such as amprolium, levamisole and ivermectin did not significantly inhibit the growth of L. casei, IMB B-7280 and E. coli 055K59 № 3912/41, since their minimal inhibitory concentration was in the range of 4000 to 6000 mg ml.


2019 ◽  
Author(s):  
Sriraam Sankar ◽  
Ramasamy Thangamalai ◽  
Sriram Padmanaban ◽  
Porteen Kannan ◽  
M R Srinivasan ◽  
...  

AbstractThe colossal rise in antimicrobial resistance has led to treatment failures and so mastitis has become cumbersome to treat. The objective of this study was to evaluate the antibacterial effect of non-antibiotic drug, atorvastatin in combination with antimicrobial, ampicillin against two commonly isolated bacterial species Staphylococcus spp and E. coli from bovine mastitis. Milk samples were collected from mastitis cows, visiting Veterinary Clinical Complex. Bacterial isolation was performed using Eosin Methylene Blue (EMB) agar and Mannitol Salt Agar (MSA), followed by characterization and identification by biochemical tests and gram staining. Genotypic confirmation was done by Polymerase Chain Reaction (PCR) with subsequent screening for resistant genes-mec A, blaTEM. Antibiotic Sensitivity Test (ABST) of the isolates against 12 different antimicrobials, atorvastatin only, and combination of atorvastatin with ampicillin were performed using Kirby-Bauer disc diffusion method. Minimum Inhibitory Concentration (MIC) of ampicillin alone and ampicillin in combination with atorvastatin were determined by modified microdilution method. Staphylococcus spp (77.5%) and E.coli (35%) were the two major pathogens isolated in the current study and multi-drug resistance was observed. Among the antimicrobials, the ampicillin showed 100% resistance against Staphylococcus spp and 85.71% resistance against E. coli. Atorvastatin did not display antibacterial effect as a sole agent but displayed synergistic antibacterial activity with ampicillin. There was an average increase in Minimum Inhibitory Concentration of ampicillin for E.coli and Staphylococcus spp isolates and atorvastatin decreased the Minimum Inhibitory Concentration of ampicillin in combination. The ampicillin shows more resistance against both Staphylococcus spp and E.coli, while atorvastatin improves the effect of ampicillin in-vitro. So, atorvastatin may be combined with ampicillin for the treatment of Gram-positive and Gram-negative infections. However, further studies are required to ascertain the exact mechanism of action of atorvastatin with respect to their antibacterial effect for them to be redeployed as an antimicrobial drug in the future.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Sahar Shahidi ◽  
Seyed Sadegh Shahraeini ◽  
Yekta Farmahini Farahani ◽  
Soroush Sardari

AbstractObjectivesThe development of novel antibiotic compounds requires riboswitches; in fact, riboswitches are RNA elements present in the 5′ untranslated region of bacterial mRNA and have a metabolite-binding aptamer domain and an expression platform regulating the expression of vital genes. In the present research, one riboswitch, namely thi-box riboswitch with distinct regulatory mechanisms, was studied. It recognizes Thiamine Pyrophosphates (TPP) regulating TPP-biosynthesis genes in Escherichiacoli.MethodsFirst, the compounds similar to riboswitch ligands were studied, and their binding with the riboswitch and nucleosides was investigated by molecular docking. Then, compounds containing high binding energy were chosen, and their minimum inhibitory concentration in E. coli was determined by the MIC test. Finally, the binding of compounds to nucleotides and RNA was investigated by measuring the absorbance spectrum through NanoDrop and circular dichroism (CD).ResultsIn the thi-box riboswitch, nalidixic acid was found to have the best binding energy (−5.31 kJ/mol), and it inhibited E. coli growth at the minimum inhibitory concentration of 125 μg/mL, and it could bind to ribonucleosides and RNA in vitro.ConclusionsOne possible mechanism involved in the action of nalidixic acid in inhibiting the E. coli growth is to influence thi-box riboswitch.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Abdulkader Masri ◽  
Naveed Ahmed Khan ◽  
Muhammad Zarul Hanifah Md Zoqratt ◽  
Qasim Ayub ◽  
Ayaz Anwar ◽  
...  

Abstract Backgrounds Escherichia coli K1 causes neonatal meningitis. Transcriptome studies are indispensable to comprehend the pathology and biology of these bacteria. Recently, we showed that nanoparticles loaded with Hesperidin are potential novel antibacterial agents against E. coli K1. Here, bacteria were treated with and without Hesperidin conjugated with silver nanoparticles, and silver alone, and 50% minimum inhibitory concentration was determined. Differential gene expression analysis using RNA-seq, was performed using Degust software and a set of genes involved in cell stress response and metabolism were selected for the study. Results 50% minimum inhibitory concentration with silver-conjugated Hesperidin was achieved with 0.5 μg/ml of Hesperidin conjugated with silver nanoparticles at 1 h. Differential genetic analysis revealed the expression of 122 genes (≥ 2-log FC, P< 0.01) in both E. coli K1 treated with Hesperidin conjugated silver nanoparticles and E. coli K1 treated with silver alone, compared to untreated E. coli K1. Of note, the expression levels of cation efflux genes (cusA and copA) and translocation of ions, across the membrane genes (rsxB) were found to increase 2.6, 3.1, and 3.3- log FC, respectively. Significant regulation was observed for metabolic genes and several genes involved in the coordination of flagella. Conclusions The antibacterial mechanism of nanoparticles maybe due to disruption of the cell membrane, oxidative stress, and metabolism in E. coli K1. Further studies will lead to a better understanding of the genetic mechanisms underlying treatment with nanoparticles and identification of much needed novel antimicrobial drug candidates.


2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e15567-e15567
Author(s):  
Lars Henrik Jensen ◽  
Anders Kristian Moeller Jakobsen ◽  
Birgitte Mayland Havelund ◽  
Cecilie Abildgaard ◽  
Chris Vagn-Hansen ◽  
...  

e15567 Background: Precision oncology based on in-vitro, functional assays has potential advantages compared to the much more common molecular approach, but the clinical benefit is unknown. We here report the results from the largest prospective interventional clinical trial testing the clinical outcome in colorectal cancer patients treated with drugs showing cytotoxic effect in matched patient-derived tumoroids. Methods: This single-center, phase II trial included patients with metastatic colorectal cancer previously exposed to all standard therapies. Specimens from one to three 18-16 G core needle biopsies were manually dissected, enzymatically treated, cultivated, and incubated to form 3D spherical microtumors, i.e. tumoroids. In the assay for in-vitro sensitivity testing, the tumoroids were challenged with single drugs and combinations thereof to determine patient-specific responses. Using tumoroid screening technology (IndiTreat, 2cureX, Copenhagen, Denmark), results were generated by comparing the sensitivity of the individual patient’s tumoroids with a reference panel from other patients. The testing included standard cytostatics and drugs with proven effect in previous early-phase clinical trials, a total of 15 drugs. The primary endpoint was the fraction of patients with progression-free survival (PFS) at two months. Based on placebo arms in randomized last-line trials, a minimal relevant difference of 20% (20% to 40%) was stated. Using Simon's two-stage design, a sample size of 45 patients was calculated with at least 14 PFS at two months (significance 5%, power 90%). Results: Ninety patients were enrolled from 9/2017 to 9/2020. Biopsies from 82 patients were obtained and sent for tumoroid formation of which 44 (54%, 95% CI 42-65) were successful and at least one treatment was suggested. Thirty-four patients initiated treatment according to the response obtained in the drug assays within a median of 51 days from inclusion (IQR 39-63). The primary endpoint, PFS at two months, was met in 17 of 34 patients (50%, 95%CI 32-68). There were no radiological responses. Median PFS was 81 days (95% CI 51-112) and median OS was 189 days (95% CI 103-277). Conclusions: Precision oncology using a functional approach with patient-derived tumoroids and in-vitro drug sensitivity testing seems feasible. The approach is limited by the fraction of patients with successful tumoroid development. The primary endpoint was met, as half of the patients were without progression at two months. Further clinical studies are justified. Clinical trial information: NCT03251612.


2021 ◽  
Author(s):  
li li jiang ◽  
Su Xu ◽  
Haitao Yu ◽  
Qi Cui ◽  
Rui Cao

Abstract In this study, graphene oxide (GO) was first prepared by the modified Hummer method. Then, the GO/trichloroisocyanuric acid (TCCA) composite was prepared by loading TCCA into GO with the blending method. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and atomic force microscopy were used to characterize the composite. The results showed that TCCA was successfully loaded on the surface of GO or intercalated among GO layers. Next, the antibacterial performance of the composite against Escherichia coli and Staphylococcus aureus was tested by the 96-well plate assay. A bactericidal kinetic curve, bacterial inhibition tests, and the mechanism of bacterial inhibition is discussed. The results showed that the minimum inhibitory concentration of the GO/TCCA composite (GO:TCCA ratio = 1:50) was 327.5 µg/mL against E. coli and 655 µg/mL against S. aureus. At the minimum inhibitory concentration, the inhibition rate of the GO/TCCA composite exceeded 99.46% against E. coli and 99.17% against S. aureus. The bactericidal kinetic curves indicate that the GO/TCCA composite has an excellent bactericidal effect against E. coli and S. aureus.


2017 ◽  
Vol 43 (1) ◽  
pp. 20-25
Author(s):  
Rosane Baldiga Tonin ◽  
Erlei Melo Reis ◽  
Aveline Avozani

ABSTRACT Reports of failure in the chemical control of wheat yellow leaf spot led to determination of the sensitivity of Drechslera tritici-repentis (Dtr) to the fungicides quinone outside inhibitors (QoIs) and demethylation inhibitors (DMIs). The IC50 was obtained for strobilurins (azoxystrobin, kresoxim-methyl, picoxystrobin and pyraclostrobin) and for triazoles (cyproconazole, epoxiconazole, propiconazole, prothioconazole and tebuconazole), using five Dtr isolates. Seven concentrations of the fungicides were tested in the bioassay: 0.00; 0.01; 0.10; 1.00; 10:00 and 20.00 and 40.00 mg/L active ingredient (a.i.). Assays consisted of completely randomized design and four replicates. Each experiment was performed twice, using the average of the two tests for statistical analysis. The percentage inhibition data for conidial germination (QoIs) and for mycelial growth (DMIs) were subjected to logarithmic regression analysis, calculating the 50% inhibitory concentration (IC50) based on the generated equation. There was a reduction in the sensitivity of Dtr isolates to strobilurins. IC50 values ranged from 0.58 to > 40.00 mg/L. The lowest sensitivity of isolates was detected for azoxystrobin, kresoxim-methyl, picoxystrobin and trifloxystrobin. Pyraclostrobin was most efficient, showing IC50 between 0.58 and 1.03 mg/L. The IC50 ranged from 0.35 to 1.37 mg/L for epoxiconazole, from 0.49 to 1.28 mg/L for propiconazole and from 1.41 to 2.34 mg/L for tebuconazole. Prothioconazole was most potent, showing IC50 between 0.09 and 0.21 mg/L. The hypothesis that the control failure can be attributed to the reduced Dtr sensitivity to the fungicides QoIs and DMIs was confirmed.


1984 ◽  
Vol 77 (9) ◽  
pp. 754-757 ◽  
Author(s):  
Robert Mills ◽  
Ann Uttley ◽  
Michelle McIntyre

A total of 204 chronic middle ear effusions from 122 children have been studied. Bacteria were isolated from 30 effusions. The commonest species found were Strep. pneumoniae and H. influenzae. These are also the commonest organisms causing acute otitis media (AOM). A similar pattern of serotypes was also demonstrated. In vitro sensitivity testing showed that most of the organisms isolated were sensitive to most commonly-used antibiotics. The main exception was resistance to penicillin amongst strains of H. influenzae and Staph. aureus. It is suggested that some cases of chronic secretory otitis media (SOM) may arise as a result of incomplete resolution of AOM and that the use of penicillin to treat AOM may be one factor in this process.


Author(s):  
Khodijah Khodijah ◽  
Ratna Farida ◽  
Nurtami Soedarsono

Objective: This experiment aimed to analyze the effect of propolis extract and propolis containing candies on the growth of Aggregatibacter actinomycetemcomitans using spectrophotometric analysis and colony-forming units (CFU) counts.Methods: After A. actinomycetemcomitans were exposed to propolis extract and candies, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined with spectrophotometry and post-exposure colony counting.Results: The MIC of propolis extract against A. actinomycetemcomitans was determined to be 10%, and the MBC was 20%. A decrease in the total CFU count of A. actinomycetemcomitans was observed after propolis extract and candy exposure.Conclusions: Propolis extract and propolis candies were effective in inhibiting the growth of A. actinomycetemcomitans ATCC 43718 in vitro.


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