Blood smear: fulminant pneumococcal bacteremia

Jonathan Lancashire and Mark Crowther

A previously fit 63-year-old woman presented drowsy, breathless, and hypotensive. Observations revealed a fever (38.6°C), hypoglycemia (2.2 mmol/L), hypotension (84/55 mmHg), and atrial fibrillation (140 bpm). Arterial blood gas demonstrated a metabolic acidosis (pH 7.19, lactate 11.4) with significant hypoxia. Laboratory investigations showed hemoglobin 144 g/L, white cell count 2.3 × 109/L, neutrophil count 1.9 × 109/L, and platelet count 9 × 109/L. The activated partial thromboplastin time and prothrombin time were prolonged, along with a depressed fibrinogen level, in keeping with disseminated intravascular coagulation. Wright-stained peripheral blood smear showed highly vacuolated neutrophils; there were a large number of both intra- and extra-cellular Gram-positive diplococci (see arrow in left panel of figure) in keeping with overwhelming sepsis. Gram stain of the peripheral blood smear affirmed the bacteremia. Later, blood culture revealed a fully sensitive Streptococcus pneumoniae, with earliest growth detected at 4 hours' incubation. Despite prompt treatment with intravenous fluids, antibiotics, and blood products, the patient continued in septic shock and died 5 hours after presentation due to cardiac arrest.

Identifying bacteria on a blood smear is a rare finding. When present, it can lead to a diagnosis before any blood cultures become positive. This can be of great value in guiding immediate management in the acute setting.


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