A good antibiotic is highly selective for its target, only killing or inhibiting the growth of bacteria. High selectivity generally results in fewer side effects for the patient, which is generally desired.
An antibiotic should be difficult to develop resistance towards, however this has yet to be discovered as many bacterial species are able to evolve rapidly due to their high replication rates. Some bacteria, such as syphilis, have yet to show widespread resistance – this is likely due to the slow replication rates of these pathogens.
Being able to kill many different bacterial species is also desired. This broad spectrum of activity means the specific species causing the infection does not need to be identified. However, with the advent of third generation sequencing technologies such as Nanopore, it may be possible to rapidly identify pathogens during clinical consultations, allowing the best antibiotic to be selected for the patient. Using a broad-spectrum antibiotic can disrupt the patient’s commensal bacteria, potentially allowing opportunistic pathogens to cause an infection (such as yeast vaginitis, Staphylococcus aureus, and Clostridioides difficile)