Every antibiotic covers a spectrum — the range of microbes it can kill. A narrow drug hits a small slice; a broad drug hits many kinds at once. The catch: the same drug that clears the infection also mows down the patient's protective normal flora. Pick a drug for this Group A Strep infection and watch the trade-off.
The patient's flora + the infection
Gram-positive floraGram-negative floraAnaerobe floraInfection: Group A Strep
Each symbol is a colony. The ringed coral chains are the infection; everything else is the body's normal flora. A faded, crossed-out symbol has been killed.