Pharmacology · patient case question
Because of her penicillin allergy, clindamycin is prescribed after the extraction. What is the most characteristic serious complication of this drug?
Patient case: Rheumatoid Arthritis and a Needed Extraction
Patient: 56-year-old female
Chief Complaint: “My back bottom left tooth has been aching for two weeks.”
Background: Rheumatoid arthritis for 12 years, currently in partial remission. Reports hives after amoxicillin as a teenager. No other systemic disease.
Medications: Methotrexate 15 mg weekly · Adalimumab (Humira) 40 mg subcutaneous every 2 weeks · Folic acid 1 mg daily
Vital Signs: BP 124/76 mmHg · HR 78 bpm · RR 16 · T 98.6°F
Findings: Maximum interincisal opening 32 mm with bilateral TMJ crepitus. Ulnar deviation of the fingers with metacarpophalangeal swelling. Tooth #18 with a grossly carious crown, non-restorable; extraction planned.
Show answer and explanation
Correct answer: C. Pseudomembranous colitis caused by Clostridioides difficile
- A. Incorrect. Tendinopathy and tendon rupture are the recognized fluoroquinolone adverse effect — ciprofloxacin and levofloxacin.
- B. Incorrect. Aplastic anemia is classically associated with chloramphenicol, which is essentially never used in dentistry.
- C. Correct. Clindamycin suppresses normal colonic flora and permits overgrowth of toxin-producing C. difficile. The result is severe watery diarrhea with abdominal cramping, which can progress to toxic megacolon. Any patient developing persistent diarrhea on clindamycin should stop the drug and seek medical care.
- D. Incorrect. Ototoxicity is characteristic of aminoglycosides such as gentamicin, and of high-dose loop diuretics.
Note: Any antibiotic can cause C. difficile colitis. Clindamycin has the strongest historical association, but broad-spectrum cephalosporins and fluoroquinolones account for more cases in absolute terms today.