UA C&S question

I was just hoping some more experienced nurses could help me out. I got a patients results of a UA C&S and I was not 100% sure on how to interpret them. I understand the R, S and I aspect but am not clear on the numeric values associated with the antibiotics and to choose the most effective. The MD was notified and ordered macrobid but I am not clear with reading the sensitivity report.

Here are some of the choices from the report, I have included some of the higher values and lower values to aid in understanding. (the patient has no renal insufficiency or allergies)

E. Coli colony count >100,000

Susceptibility

Cipro <0.25
Macrobid 32
Levaquin <0.12
Bactrim <20

I am looking to find the reasons why the higher numeric value was chosen. I am apparently wrong....but was under the impression that the lower the numeric value the more effective a antibiotic was and the higher the value meant more of the antibiotic was required?

Help if you can please!
The numbers indicate the size of "zone of inhibition." Culture is grown on a plate with little disks saturated with each antibiotic. If the microorganism is susceptible to a particular antibiotic, it would not grow around that disk. More susceptible the organism to the antibiotic, the greater the zone of inhibition would be. See the picture:

So the greater the susceptibility to the antibiotic, the larger the zone, and the greater the number will be? Very cool. Thank you for the microbiology lesson!

Quote from tokebiThe numbers indicate the size of "zone of inhibition." Culture is grown on a plate with little disks saturated with each antibiotic. If the microorganism is susceptible to a particular antibiotic, it would not grow around that disk. More susceptible the organism to the antibiotic, the greater the zone of inhibition would be. See the picture:

I'm glad I got to contribute to the learning opportunities of Allnurses. But the credit entirely goes to my amazing micro teacher from years ago. Thank you all the teachers out there!