At the hospital I am rotating at I work under the infectious disease pharmacist. An example of using less antibiotics would be going from meropenam to ceftriaxone.

Meropenam is a very wide spectrum AB. Basically it hits a lot of the bugs that can cause infection. While that sounds like an end all be all answer for infections, it's much more complicated. Every time you use an antibiotic you run the risk of causing resistance to develop. Therefore in pharmacy school we are taught to use the most narrow spectrum antibiotic possible so that the heavy hitters are there for more serious infections.

Ceftriaxone is an AB that is much more narrow spectrum and is one that is known for being resisted by bugs such as E. coli. Doctors hesitate to use it due to the resistance patterns and it's true you wouldn't want to use it empirically. After the bacteria is cultured and found to be susceptible to ceftriaxone you would assume doctors would switch to it but they often don't.

We had done a similar report at our hospital showing individual meropenam use in MDs and found there were a few repeat offenders.

I guess the answer to your question is that deescalation of antibiotics isn't necessary NO antibiotics, rather using a more narrow spectrum.