Final answer:
To evaluate an antibiotic's effectiveness, a PN should monitor WBC count and results from cultures and sensitivity tests. If initial treatment fails, AST guides the decision for alternative antibiotics like azithromycin in case of penicillin-resistant bacteria.
Step-by-step explanation:
To evaluate the effectiveness of an antibiotic administered to a client with a respiratory tract infection, the practical nurse (PN) should monitor several key laboratory values. These include white blood cell (WBC) count, which can reflect the presence and severity of infection, as well as specific tests such as cultures and sensitivity tests, including sputum cultures for respiratory infections. Cultures can identify the causative organism, and sensitivity tests determine the antibiotic's effectiveness against it. Additionally, antimicrobial susceptibility testing (AST) provides valuable information regarding which antibiotics are likely to be effective in treating the infection.
If the initial antibiotic was ineffective, as suggested by the lack of improvement in symptoms or laboratory values, the healthcare provider may consider alternative antibiotics based on the results of the AST and the infection's resistance patterns. For instance, if amoxicillin is ineffective against pneumonia, as indicated in the clinical focus scenario, another antibiotic such as azithromycin, which targets bacterial ribosomes, might be prescribed. Azithromycin is often effective against a broader range of bacteria and may be a suitable alternative if the causative agent is resistant to penicillin derivatives.