Could you provide the material that says this?
Here is a little bit about Ceclor:
https://www.drugs.com/pro/cefaclor.html#s-34067-9
“Note:lactamase-negative, ampicillin-resistant (BLNAR) strains of Haemophilus influenzae should be considered resistant to Cefaclor despite apparent in vitro susceptibility of some BLNAR strains.”
There are others, but I don’t have the internet addresses for them, but it said in the package insert that you get with prescription medication and I always read it.
But here is one example for you, it’s not supposed to work against influenza, but it does.
But always consult with your doctor, read the package insert, and make up your own mind.
I just shared my experiences and opinion.