Final answer:
A good chemotherapeutic target for treating gram-negative bacterial infections is the bacterial outer membrane, as it provides selective toxicity. Polymyxin is an example of such a drug.
Step-by-step explanation:
A good target for a chemotherapeutic drug used to treat a bacterial infection would be a structure or mechanism that is specific to bacteria, ensuring selective toxicity.
An ideal target would be the bacterial outer membrane, which is unique to gram-negative bacteria. A classic example of a drug that targets this structure is polymyxin.
Polymyxins disrupt the outer membrane of gram-negative bacteria, leading to cell death. This disruption does not occur in human cells as they lack this outer membrane.
Narrow-spectrum antimicrobial drugs are often preferred in clinical situations where the causative bacterial pathogen is clearly identified and is known not to belong to a diverse range of bacteria.
This helps avoid collateral damage to the patient's normal microbiota and reduces the likelihood of developing antimicrobial resistance.
For instance, isoniazid specifically targets mycobacteria, making it an effective narrow-spectrum antibiotic for diseases like tuberculosis.