What is the primary concern with antibiotic overuse?

The primary concern with antibiotic overuse is the development of antibiotic resistance. When antibiotics are used excessively or inappropriately, bacteria can evolve and adapt to the presence of these medications, making them less effective or even ineffective over time. This resistance occurs through natural selection; susceptible bacteria are killed off, leaving behind those that can survive despite antibiotic treatment. As a result, infections become harder to treat, leading to prolonged illness, increased medical costs, and a higher risk of complications and mortality.

Given the context of the other options, they do not address the long-term implications of antibiotic misuse. Increased patient compliance may improve adherence to treatment but does not pertain to the consequences of antibiotic resistance. Improvement of treatment outcomes can occur with appropriate antibiotic use, but overuse typically has the opposite effect. While higher healthcare costs could be associated with managing resistant infections, they are a secondary concern compared to the critical issue of diminished effectiveness of antibiotics. Thus, antibiotic resistance remains the foremost worry in public health and clinical practice.