An 80-year-old male with a history of valve replacement for severe aortic stenosis and aortocoronary bypass presented to the emergency department of the Pontevedra Hospital, having experienced asthenia for almost 1 week and morning fever without shivering for the past 48 h. The initial examination showed a good general state. He had neither a headache nor focal neurological signs. No urinary or digestive symptoms were observed. A chest X ray and transthoracic echocardiography ruled out pleuropulmonary pathology and acute endocarditis. The urinary sediment analysis results were normal, and biochemical markers did not indicate heart damage (cardiac troponin I < 0.04 ng/ml). In the presence of fever (38.4°C), leukocytosis (12,600 cells/mm3 with 76.2% neutrophils), and a high C-reactive protein level (12.1 mg/dl), empirical antibiotic treatment was initiated with intravenous levofloxacin and the patient was admitted to the hospital to assess his progress. Blood and urine cultures, serologic testing, and an abdominal ultrasound scan were requested.
During the following days, the patient remained asymptomatic and hemodynamically stable, with a persistent low-grade fever. The urine culture was negative, and the abdominal ultrasound scan results were normal. The serology results were negative for hepatitis B virus, hepatitis C virus, HIV, Treponema pallidum, Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydia pneumoniae and showed past infection with cytomegalovirus and Epstein-Barr virus. The two sets of blood cultures were incubated in the BD Bactec FX system (Becton Dickinson Biosciences), which detected bacterial growth in all bottles (BD Bactec Plus Aerobic/F and Plus Anaerobic/F media) in less than 4 h. The initial Gram stain revealed Gram-positive coccobacilli. The blood culture broth was subcultured in blood agar, chocolate agar, and brucella agar, and after 24 h of incubation at 37°C, a gray colony of about 2 mm in diameter with the appearance of enterococcus was isolated on blood agar. The Gram stain of the colony confirmed Gram-positive coccobacilli (Fig. 1). Enterococcus faecium was identified using the API 20 Strep system (bioMérieux), with 95.0% probability, but an atypical antibiotic susceptibility testing result prompted additional testing.
FIG 1.
Gram stain from the gray colony isolated on blood agar after 24 h of incubation. Magnification, ×1,000 (oil).
For answer and discussion, see https://doi.org/10.1128/JCM.03358-15 in this issue.