Is It Precipitated Stain or Is It Bacteria?
A 24-year-old man presented to the emergency department with a fever of unknown origin. A CBC, blood cultures, and routine chemistries were ordered. The chemistries came back as normal and the blood cultures would be read in 24 hours. The CBC results were as follows:
Platelets 598 X 109/L H
The elevated WBC was flagged, and reflex testing required that a manual differential be completed. The technologist, upon reviewing the peripheral smear, noted several items:
The 35.0 X 109/L WBC count correlated with the slide.
Many band forms were seen.
The patient's peripheral smear seemed to show the presence of bacteria intracellularly and extracellularly; however, the technologist was fairly new to the hospital facility, and because this was such an important finding, he needed assistance in making a definite identification.
Differentiating precipitated stain from bacteria is often difficult, yet there are some distinct characteristics that can make the identification easier. Microorganisms or bacteria are uniform in size and shape and are usually dispersed throughout the slide. They may be found randomly throughout the peripheral smear, and in most cases, they are lucky to be visualized at all. Precipitated stain, on the other hand, tends to appear in aggregates, which are localized and plentiful. Additionally, precipitated stain tends to lack an organized morphology and looks smudgy or clumpy. In the case of our patient, the technologist consulted several of his peers. Through consensus, it was agreed the inclusions were bacteria. The pathologist was notified and the floor was contacted. The blood cultures were positive, and the patient was started on high-dose antibiotics and made a complete recovery.
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