Bacterium Inoculums preparations for the MIC and MBC experiments
From the previous isolated and identified MRSA and VRSA S. aureus isolates, four MRSA+VRSA and four MRSA+VSSA isolates were chosen for MIC and MBC experiments. With a sterile loop, a loopfull from each chosen isolate was inoculated from the BHI slant into MH broth then incubated with shaking at 37°C overnight for 24 hours. The concentrations of these suspensions were adjusted to be equal to the 0.5 McFarland standards by adding a sterile saline. Test and standard tubes were compared against a white background with a contrasting black line. Then the Suspensions concentrations were adjusted by spectrophotometer to an optical density of 0.10 at 625 nm to obtain the concentration …show more content…
angustifolia extract, honey and AuNPs against the eight chosen S. aureus isolates (four MRSA+VRSA and four MRSA+VSSA) were analyzed through determination of their minimum inhibitory concentrations (MIC) values, minimum bactericidal concentrations (MBC) values, and MBC/MIC ratio by broth micro-dilution method using 96-well micro-titer plates. To each 50 μL of the antibacterial agent dilution, 50 μL of adjusted bacterial concentration inoculum (5 × 105 CFU/mL) were added in the 96-well micro-titer plates, the growth control wells contained MH broth medium with tested bacterial concentrations and sterility control wells contained only MH broth medium as shown in figure 2. The plates were then covered to ensure that the bacteria were not dehydrated. Then the plates were incubated at 37°C for 18 to 20 hours. The lowest concentration of each antibacterial agent that inhibited the bacterial growth was considered as the MIC (CLSI, 2006). After the MIC determination, aliquots of 100 μL from each well that does not show any bacterial growth after incubation were streaked onto BHI agar plates followed by incubation at 37°C for 20 hours. The lowest concentration that kills 100% of the initial bacterial population showing no colonies on the BHI agar was recorded as the
From the previous isolated and identified MRSA and VRSA S. aureus isolates, four MRSA+VRSA and four MRSA+VSSA isolates were chosen for MIC and MBC experiments. With a sterile loop, a loopfull from each chosen isolate was inoculated from the BHI slant into MH broth then incubated with shaking at 37°C overnight for 24 hours. The concentrations of these suspensions were adjusted to be equal to the 0.5 McFarland standards by adding a sterile saline. Test and standard tubes were compared against a white background with a contrasting black line. Then the Suspensions concentrations were adjusted by spectrophotometer to an optical density of 0.10 at 625 nm to obtain the concentration …show more content…
angustifolia extract, honey and AuNPs against the eight chosen S. aureus isolates (four MRSA+VRSA and four MRSA+VSSA) were analyzed through determination of their minimum inhibitory concentrations (MIC) values, minimum bactericidal concentrations (MBC) values, and MBC/MIC ratio by broth micro-dilution method using 96-well micro-titer plates. To each 50 μL of the antibacterial agent dilution, 50 μL of adjusted bacterial concentration inoculum (5 × 105 CFU/mL) were added in the 96-well micro-titer plates, the growth control wells contained MH broth medium with tested bacterial concentrations and sterility control wells contained only MH broth medium as shown in figure 2. The plates were then covered to ensure that the bacteria were not dehydrated. Then the plates were incubated at 37°C for 18 to 20 hours. The lowest concentration of each antibacterial agent that inhibited the bacterial growth was considered as the MIC (CLSI, 2006). After the MIC determination, aliquots of 100 μL from each well that does not show any bacterial growth after incubation were streaked onto BHI agar plates followed by incubation at 37°C for 20 hours. The lowest concentration that kills 100% of the initial bacterial population showing no colonies on the BHI agar was recorded as the