Many antibiotics classes seem to be partially selective at killing either Gram+ species or Gram- species.
For example, fluoroquinolones can kill both Gram+ and Gram- microbes, but they are generally better at killing Gram-.
Other classes have the reverse characteristics.
I don't know much about the types of microbes that cause periodontal disease.
However, my company was initially interested in treating Community Acquired Pneumonia (CAP). The problem with CAP (and many other bacterial infections) is that they can be caused by either Gram+ or Gram- pathogens. This means that if you're making a drug to treat CAP, you need an antibiotic that can "hit" both types.
A common occurrence when we were looking for a candidate drug that could treat CAP was that the candidate would be powerful at killing Gram+ CAP microbes and weak at killing Gram- CAP species. If we improved the drug's ability to "hit" Gram- species, we would always seem to lose potency against Gram+. It was extremely tricky to find something that was powerful enough against _all_ the relevant microbial pathogens.
For example, fluoroquinolones can kill both Gram+ and Gram- microbes, but they are generally better at killing Gram-.
Other classes have the reverse characteristics.
I don't know much about the types of microbes that cause periodontal disease.
However, my company was initially interested in treating Community Acquired Pneumonia (CAP). The problem with CAP (and many other bacterial infections) is that they can be caused by either Gram+ or Gram- pathogens. This means that if you're making a drug to treat CAP, you need an antibiotic that can "hit" both types.
A common occurrence when we were looking for a candidate drug that could treat CAP was that the candidate would be powerful at killing Gram+ CAP microbes and weak at killing Gram- CAP species. If we improved the drug's ability to "hit" Gram- species, we would always seem to lose potency against Gram+. It was extremely tricky to find something that was powerful enough against _all_ the relevant microbial pathogens.