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Oral Administration of Lipid-Based Delivery Systems to Combat Infectious Diseases
Published in Ana Rute Neves, Salette Reis, Nanoparticles in Life Sciences and Biomedicine, 2018
Rita M. Pinto, Daniela Lopes, Cláudia Nunes, Bruno Sarmento, Salette Reis
In vitro assays are valuable tools to assess the therapeutic efficacy of antimicrobial NPs. For bacteria, in vitro antimicrobial activity studies are based on the determination of the minimum inhibitory concentration (MIC) and of the minimum bactericidal concentration (MBC) [107]. The MIC can be defined as the lowest concentration of a antimicrobial agent required to inhibit visible growth of an inoculum of the bacterium in a broth dilution test [108]. On other hand, MBC is the minimal concentration of a antimicrobial agent able to kill ≥99.9% of the initial inoculum within 24 h, and it is determined from broth dilution MIC tests by subculturing onto antibiotic-free agar media [108]. For instance, in the work of Dong et al. serial dilutions of NP suspensions were mixed with S. aureus to a final bacterial concentration of 5.5 × 105 CFU/mL [73]. The mixture was posteriorly incubated at 37°C for 12 h and 24 h, with shaking [73]. Usually, the MIC is determined by a visual comparison of the medium turbidity of the cultures and the control tubes [108]. Alternatively, the MIC value can be determined by spectroscopy [110]. MBC is measured by subculturing the broths previously used for MIC measurement onto fresh agar plates at 37°C [73]. Therefore, the microbial colonies are counted when they are observed by the naked eye [73]. Besides the determination of MIC and MBC, studies of NP-pathogen interactions can be performed, such as agglutination assays, epifluorescence studies, TEM technique, and quantification of bacterial adhesion using luminescence [19]. These studies are reported in more detail elsewhere [19].
Studies on a new antimicrobial peptide from Vibrio proteolyticus MT110
Published in Preparative Biochemistry & Biotechnology, 2023
Himanshu Verma, Kanti N. Mihooliya, Jitender Nandal, Debendra K. Sahoo
MIC is defined as the minimum concentration of the antimicrobial agent, which inhibits the visible growth of the test organism after incubation of 16–20 h under test conditions. In this study, the MIC of peptide-MT110 was determined against six indicator strains, i.e., S. aureus MTCC 1430, S. mutans MTCC 497, E. coli MTCC 1610, A. baumannii ATCC 19606, V. vulnificus MTCC 1146, and P. aeruginosa MTCC 1934 in microtiter plate using broth dilution assay, described by Wiegand et al.,[20] in which plates were incubated at 37 °C for 24 h, and the absorbance was read at 600 nm. The MBC of pure peptide-MT110 was determined using the method described by Tong et al. 2010,[21] with a few modifications. MBC is the lowest dose of antimicrobial agent that suppresses the observable growth of test organisms. For MBC, 10 μL from a 24 h incubated microtiter well plate of MIC, where no bacterial growth was detected, and distributed on different nutrient agar plates, incubated at 37 °C for 24 h and colony formation were evaluated; those plates where no colony was seen were considered MBC. All MBC tests were done three times.
Study of antibacterial and antioxidant activities of silver nanoparticles synthesized from Tradescantia pallida (purpurea) leaves extract
Published in Journal of Dispersion Science and Technology, 2023
Romana Naaz, Vasi Uddin Siddiqui, Amina Ahmad, Sami Ullah Qadir, Weqar Ahmad Siddiqi
MIC refers to the lowest concentration of antibiotic that prevents evident bacterial growth while MBC is the lowest concentration that kills 99% of bacteria after inoculation of the MIC for 24 hours. MIC techniques are commonly utilized to test novel medicines quantitatively or to obtain a more precise diagnosis or treatment.[46] By using a broth microdilution process, the MIC was determined. Serial concentrations of AgNPs were prepared in sterile 96-well plates, and the first-row plates (row A) were assigned to blank/negative and uncontrolled growth controls, using only MH broth media. A diluted overnight broth culture was added to each well, which ranged in concentration from 0.75 to 200 µg/mL, adjusted to a McFarland turbidity standard of 0.5.[47] The plates were then incubated for 24 hours at 37 °C. Following overnight incubation with an antibacterial drug (AgNPs) that prevents microorganism growth, the MIC and MBC was determined.[4,24]
Selected fungi of the genus Lactarius - screening of antioxidant capacity, antimicrobial activity, and genotoxicity
Published in Journal of Toxicology and Environmental Health, Part A, 2022
Miroslava Stanković, Violeta Mitić, Vesna Stankov Jovanović, Marija Dimitrijević, Jelena Nikolić, Gordana Stojanović
The MBC is the lowest concentration of an antimicrobial for inhibiting the growth of a microorganism agent, and thus considered an essential parameter to determine the sensitivity of a bacteria to an antibacterial. A higher MBC value for a specific microorganism indicates a lower antimicrobial agent needs to be employed. For this reason, it is one of the most reliable techniques to determine the antimicrobial properties of a substance. Table 3 shows the MIC/MBC mushrooms extracts against 9 pathogenic bacteria. All examined extracts demonstrated an inhibitory effect against B. cereus (MIC 4.69 mg/ml). The most effective extract against E. faecalis was L. sanguifluus with MIC 2.35 mg/ml . Further, samples L. volemus, L. sanguifluus and L. piperatus displayed an inhibitory activity (MIC 4.69 mg/ml) against E. faecalis. The inhibitory effect was observed in L. volemus, L. sanguifluus and L. piperatus against E. aerogenes (MIC 4.69 mg/ml), but no bactericidal effect. Significant results were found in the inhibitory activity of all examined extracts against P. aeruginosa, S. enteritidis, S. aureus and L. monocytogenes. There were no inhibitory activities against P. mirabilis and E. coli. It is important to note that none of the extracts of the examined Lactarius mushroom exhibited a bactericidal effect (MBC in the range 18.75–37.5 mg/ml).