An 85-year-old man presented to the emergency department of Tacoma General Hospital with a 1-week history of left hemiparesis, ataxia, dysphagia, dysarthria, and facial droop. He had been receiving prednisone (30 to 40 mg/day) as immunosuppressive therapy for glomerulonephritis and chronic obstructive pulmonary disease for 4 months. On admission, he denied nausea, vomiting, abdominal pain, or respiratory distress.
Magnetic resonance imaging (MRI) of the brain revealed a right frontal lobe multiloculated lesion measuring 2.3 by 4.3 by 2.7 cm with significant ring enhancement and marked diffusion restriction, indicating an abscess with surrounding edema (Fig. 1D). A midline shift due to mass compression of the right ventricle was also noted. A craniectomy was performed, and drainage from the abscess was sent to the microbiology laboratory for bacterial, fungal, and mycobacterial culture. The patient was treated empirically with metronidazole and ceftriaxone.
FIG 1.
(A) Colony morphology on chocolate agar plate on day 2; (B) Gram stain of colony (magnification, ×1,000); (C) modified Kinyoun stain of colony (magnification, ×1,000); (D) longitudinal-relaxation-time (T1)-weighted axial section of MRI brain scan, showing right frontal lobe multiloculated lesion with surrounding edema.
Direct Gram staining of the drainage showed few white blood cells and no organisms. After 2 days of incubation, pure growth of small, smooth, creamy colonies was observed on sheep blood and chocolate agar plates (Fig. 1A). Growth was also seen on potato dextrose agar. The Gram stain and the modified Kinyoun stain of the colonies are shown in Fig. 1B and C, respectively. Based on the patient's clinical presentation and culture results, what is your diagnosis?
For answer and discussion, see https://doi.org/10.1128/JCM.01208-16 in this issue.