Blood/Blood Cells and Cellular Components ›› Red Blood Cells ›› Abnormal

Bacterial contamination in peripheral blood smear*

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Microscopic Features:
  • Bacterial colonies (usually cocci in chains and clusters) over RBCs
  • The contaminating bacteria are usually cocci (dark blue round structures much smaller than the RBC)
Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
  • PB: None
  • BM: None
  • LN: None
May Resemble:
  • Platelets overlying red blood cell
  • Artifacts (e.g. Stain precipitate)
  • Real Bacterial infection
Differential Diagnoses:

Real bacterial infection involving blood

Classic Immunophenotype:
  • N/A
Cartoon Image:

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  • Bacterial colonies (usually cocci: most likely Staphlococcus epidermidis) from contaminated handling during processing of the peripheral blood smear by the medical technologist

Content Editors/Website Administrators:
Hooman H. Rashidi, MD; John C. Nguyen, MD