A 74-year old woman presented to the emergency room with difficulties in speaking and standing. The patient was not able to answer the clinicians’ questions, but her husband explained that she had been ill with a fever and a worsening cough for the last 2 weeks and had taken a fall 2 days before, which had resulted in a face trauma. The patient suffered from diabetes and was on metformin, but she had neither consulted a doctor nor taken antibiotic therapy for her cough. At first, the patient was agitated and had a high respiratory rate and impaired speech but could move spontaneously and avoid painful stimuli. Her heart rate was increased (150 beats/min), her blood pressure was 110/60 mm Hg, and her body temperature was normal. Oxygen saturation passed from 90% to 96% with the use of a Venturi mask with 35% oxygen flux. Glycemia was measured at 624 mg/dl. The patient started insulin therapy and fluid infusion. Blood and urine samples were sent to the laboratory, including two blood culture sets (BacT/Alert FA/FN bottles; bioMérieux). The only abnormal results were increased blood and urine glucose levels, increased white blood cells (19 × 109/liter) and inflammation indices (C-reactive protein [CRP] > 500mg/dl), and moderately increased creatinine levels (2.53mg/dl). Urinary antigen test results for Legionella pneumophila and Streptococcus pneumoniae (Alere Binax NOW) were negative. Brain and facial mass computed tomography (CT) scans and chest X-rays were prescribed together with a neurological consultation. In the following hour, empirical antimicrobial therapy with ceftriaxone (2 g twice a day) and azithromycin (500 mg per day) was introduced. The patient’s condition worsened, with progressive decrease of spontaneous speech, which, when uttered, was incomprehensible. The CT scan did not show any masses or bone fractures. Chest X-rays revealed diffused hyperdensity in the right lung. The consultant neurologist performed a lumbar puncture. Cerebrospinal fluid (CSF) was limpid, glucose was 289 mg/dl, proteins were 81 mg/dl, and the cell count was slightly increased (4 cells/µl). The CSF Gram stain did not show any bacteria. After 12 h of incubation, aerobic blood culture bottles for both sets turned positive, and the Gram stain results are shown in Fig. 1. Blood agar (BBL Columbia agar with 5% sheep blood; Becton Dickinson) and chocolate agar (chocolate agar-PolyViteX; bioMérieux) plates inoculated from blood culture bottles were negative after 24 h of incubation under aerobic conditions (35°C; 5% CO2). Similarly, the CSF culture was negative. The antibiotic therapy was not modified.
Gram stain from positive blood culture bottle.
What might the isolated microorganism be?
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