Question

our diferent-richuring antibic Data Analysis: Tube (Broth) Dilution Test The following data were obtained for four different antibiotics (Doom, K.O., Mortum and Steril) by incubating Pseudomonas aeruginosa in a nutrient-rich medium with various concentrations of each antibiotic for 24 hours. This was followed by a subculturing step where each initial culture was used to inoculate a sterile nutrient-rich medium that contained NO antibiotic. Please use the following table to answer questions #1-4 below. (5 points possible) (+) represents growth of Pseudomonas (-) represents no visible growth K.O. Subculture Initial Growth Subculture DOOM Initial Drug Concentration Growth 200 ug/mL 100 ug/mL 50 pg/mL 25 ug/mL STERIL Initial Growth Subculture Subculture MORTUM Initial Drug Concentration Growth 200 ug/mL 100 pg/mL 50 ug/mL 1. Which antibiotic was the most effective at stopping the growth of Pseudomonas? (Hint: "Most effective," in this case, is in direct reference to the lowest concentration of antibiotic that inhibits microbial growth.). 2. Which antibiotic(s) was(were) bactericidal? 3. Based on the dilution series shown, what was the minimal inhibitory concentration (MIC) for Mortum? _(You must include units for credit!) 4. Based on the dilution series shown, what was the minimal bactericidal concentration (MBC) for Mortum? (You must include units for credit!)

Please explain why for 3&4

Answer 1

3. The Minimum Inhibitory Concentration for Mortum is 50 $\mu$ g/mL

(MIC is the concentration of drug at which stops the growth of bacteria, but doesn't necessarily kill them. At 50, the bacteria has no growth in the initial culture, but resumes growth in the subculture where there is no antibiotic. Thus the bacteria was just inhibited from growing, but were not killed at this concentration. This happened at 100 also, but the minimum inhibitory concentration will be 50.)

4. The minimal bactericidal concentration for mortum is 200 $\mu$ g/mL

(MBC is the concentration of antibiotic where the bacteria is totally killed. This happened in 200 concentration as it shows no initial growth as well as no growth in the subculture, meaning all the bacteria in the initial culture had been killed by mortum.)