Would you recommend penicillin to treat an infection?

Penicillin can be used effectively against Gram positive bacteria.
Penicillin "attacks" peptidoglycan molecules on the membrane of bacteria.
In Gram + bacteria peptidoglycan makes up about 90% of their cell wall and it is in the outermost layer.Therefore penicillin can react with these peptidoglycan molecules.
On the other hand gram negative bacteria have peptidoglycan in their cell walls but that cell wall in NOT the outermost layer.Their cell wall is located between the plasma cell and an outer LPS layer.Therefore penicillin cannot react with the peptidoglycan molecules of Gram - cells.