Minimum inhibitory concentration dilution tests

Minimum Inhibitory Concentration measured by dilution of test compound in agar inoculated with microorganism. 

The microdilution method was employed for antibacterial and antifungal activity tests. Media were placed into each well of the 96 well-microplate. Extract solutions at 1,024 pg/ml were added into first raw of microplates and twofold dilutions of the compounds (512-0.25 pg/ml) were made by dispensing the solutions to the remaining wells. Ten microliters of culture suspensions were inoculated into all the wells. The sealed microplates were incubated at 35°C for 24 and 48 h in humid chamber. The lowest concentration of the extracts that completely inhibit macroscopic growth was determined and minimum inhibitory concentrations (MICs) were... 

The question of whether or not a polymer-anchored biocide can be active against microorganism growth was first tested by comparing the minimum inhibitory concentrations (MIC) of pentachlorophenol, its acrylate, 8, and the homopolymer of pentachlorophenyl acrylate 8. An agar dilution method was used. To a sterilized agar, a solution of the compound to be tested was added in the appropriate amount to make final concentrations of 1000, 500, 250, 100, 50, and 10 ppm. Following inoculation, the... 

Antimicrobial activity was tested on standard strains of Enterococcus faecalis 4224, Staphylococcus aureus 3953 and 4223, Pseudomonas aeruginosa 3955 and Escherichia coli 3954, 3988 and 4225 (Czech Collection of Microorganisms, Brno). Microtiter wells containing serial twofold dilutions of samples are incolulated with a standard inoculum of the bacterium in question, the plates are incubated overnight, and the wells are then examined for the presence of bacterial growth. The lowest of each sample dilution series that prevents bacterial growth is considered to be the minimum inhibitory concentration (MIC) of the sample. 

EM s chemical structure consists of a 14-membered macrocyclic lactone ring (erythronolide) connected to a deoxyamino sugar (desosamine) and a deoxy sugar (cladinose) as shown in Fig. 5. We synthesized about 250 EM derivatives and examined their GMS and antibacterial activities [19, 20]. GMS activity was tested by intravenous injection of the test compounds to fasted conscious dogs with permanently implanted force transducers in the stomach, and antibacterial activity was estimated as minimum inhibitory concentration (MIC) by agar dilution method. The EM derivatives shown in Fig. 5 exhibited higher GMS activities with less antibacterial activities compared with those of EM (Table I). 

A row-dilution test (Sadler and Binder, 1996) was carried out in order to determine the anti-bacterial effect of different test substances (organic acids). This trial design made it possible to determine the minimum inhibitory concentration (MIC) required for bacteriostasis (Drews, 1983). The substances that were used in the test are listed in table 4. 

Table 2. Minimum Inhibitory Concentration (MIC) shown by complexes against test bacteria by using agar dilution assay. (—) No activity, a Bacillus cereus (MTCC 1272) b Staphylococcus aureus (MTCC 1144) c Escherichia coli (MTCC 739) d Salmonella typhi (MTCC 733) Cefaclor and Linezolid are standard antibiotics.

Antifungal bioassay. Known amounts of the pure test compounds were dissolved in DMSO and serial dilutions prepared in the same solvent. A 20 1 aliquot of each solution was mixed with 2 ml of Emmons liquid medium seeded with ca. 2 X 10 CFU/ml of the test organism. The inoculated tubes were vortexed and incubated at 26 C. Similarly, inoculated tubes without test compounds served as controls. Depending on the growth characteristics of the test species, results were recorded after 2-4 days. The lowest concentration of the test compound that totally inhibited growth of test organism was recorded as the minimum inhibitory concentration (MIC) for that species. 

Both equations confirm that AMP belonging to that set, act through electrostatic interactions with bacterial membrane [15], However, a good cannot capture the quality of an activity model because the intrinsic experimental error in microbiological tests, due to serial dilutions, is not considered. It is more correct to talk about activity classes, and the goodness of a QS AR model must be judged in terms of its ability to discriminate among very active, active and non-active peptides. For this reason, MIC (minimum inhibitory concentration expressed in pM) values of 0.3 and 1.8 must be considered as peptides with the same activity. To evaluate the models, we divided the peptides in classes of MIC as shown in Table 1. The 5 classes have similar dimension. 

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