Pharmacology · patient case question
A patient has been on antibiotic therapy for several days without improvement. What is the most appropriate next step?
Patient case: Choosing and stopping drugs
demo: Series of prescribing decisions
chief: Several patients seen in one session raise questions about antibiotic choice, analgesia and anticoagulation.
history: One patient has a spreading odontogenic infection unresponsive to five days of empirical antibiotics. Another takes rivaroxaban for atrial fibrillation. A third developed a widespread blistering rash and mucosal ulceration a week after starting a new medication.
meds: Varies by patient.
findings: Not applicable.
Show answer and explanation
Correct answer: B. Obtain a culture and sensitivity test
- A. Raising the dose of an agent the organism may be resistant to achieves nothing beyond increasing toxicity.
- B. Correct. Failure of empirical therapy is the definitive indication for culture and sensitivity. It identifies the organism and shows which agents it is susceptible to, converting guesswork into targeted therapy. The same test answers the question of which antibiotic to prescribe when the organism is unknown and the infection is not straightforward.
- C. Persisting with a failing regimen allows the infection to progress and is how odontogenic infections reach the fascial spaces.
- D. Adding another empirical agent broadens exposure and side effects without addressing the fundamental uncertainty about the organism.
Note: Culture is most useful when combined with adequate surgical drainage and removal of the source. No antibiotic substitutes for drainage.