September 2022 – Presented by Dr. Heather Greene (Mentored by Dr. Anna Romanelli and Ellen Papathakis, CLS)

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Clinical History

A 6-month-old male was brought to the Emergency Department following an episode of rigors and inconsolable crying. For several days prior, the patient’s mother noticed he was more fatigued and had an intermittent fever up to 40.5 degrees Celsius. For the last few days, the patient’s older sister had been kept at home due to being sick with a cough. On evaluation in the Emergency Department, the patient was found to be dehydrated and brightened after administration of fluids. Thought to have a viral illness, he was discharged with close follow-up.

Fourteen hours after collection, the patient’s aerobic blood culture bottle was flagged as positive. Gram stain results are shown in Image 1. The organism was rapidly identified using the BioFire FilmArray blood culture identification system and was also plated onto 5% sheep’s blood, chocolate, and MacConkey agar plates.

The patient’s family was called, and they were asked to urgently return to the hospital. Upon arrival, a lumbar puncture was performed to obtain a cerebrospinal fluid sample. A stat gram stain of the CSF revealed organisms and is pictured in Image 2. Further testing was performed using the Biofire FilmArray Meningitis/Encephalitis Panel, which identified the same organism that was detected from the patient’s blood. The patient was started on ceftriaxone as further workup of the culture was performed.

When the plates were reviewed the following day, there was growth on the chocolate agar, but not on the sheep blood or MacConkey agar plates. The chocolate agar plate is pictured in Image 3. When a lawn of the organism was plated onto blood agar with a streak of Staphylococcus aureus (satellite test), the organism only grew adjacent to the S. aureus colonies (Image 4).