Meningococcemia Diagnosed by Peripheral Blood Smear

Excerpt

A college student in previous good health presented with recent onset of fever, rigors, headache, and nuchal rigidity. A routine peripheral blood smear showed many intraleukocytic and extracellular cocci and diplococci (Figure). The organisms appeared purple in the Wright-stained preparation, but the presence of a high-grade bacteremia was unmistakable. The diagnosis of meningococcemia was confirmed by a lumbar puncture, which revealed gram-negative diplococci, and later Neisseria meningitidis group B was grown from both cerebrospinal fluid and blood.

Microorganisms are infrequently visualized in peripheral blood films,¹ although it has been reported that examination of the buffy-coat layer is sometimes helpful in making an early diagnosis of septicemia.² In most instances only rare organisms are seen within phagocytic cells of the buffy coat, but their presence is strong evidence of bacteremia (or fungemia). When large numbers of organisms are present, it is important to rule out pseudobacteremia caused by contaminated