A 58-year-old man with poorly controlled diabetes mellitus presents with fever, right upper quadrant pain, and a leukocyte count of 22,000/mm3. Blood cultures grow a gram-negative, lactose-fermenting organism. Contrast CT shows a solitary 7 cm left lobe abscess. Two days later he reports sudden blurring of vision in the right eye. The most likely causative organism is:
- A Escherichia coli
- B Streptococcus milleri group
- C Klebsiella pneumoniae (hypervirulent strain) ✓
- D Entamoeba histolytica
Explanation
Monomicrobial community-acquired pyogenic liver abscess caused by hypervirulent Klebsiella pneumoniae classically affects diabetic patients and is notorious for hematogenous metastatic spread, especially metastatic endophthalmitis presenting as sudden visual loss, as occurred here. Entamoeba histolytica causes amoebic liver abscess, which is typically a single right lobe abscess with anchovy sauce pus and no bacteremia, making it incompatible with the positive blood culture. E. coli abscesses usually arise secondary to biliary tract infection and are polymicrobial, without the distinctive metastatic ocular complication.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.