Size and Appearance of Nonbacterial Cellular Elements on Gram-stained Smears - LabCE.com, Laboratory Continuing Education

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Size and Appearance of Nonbacterial Cellular Elements on Gram-stained Smears

Table 1. Size and Appearance of Nonbacterial Cellular Elements on Gram-stained Smears.

Type of Cell	Average Size	Image	Comments
Epithelial cells	25 µm		Appear pink/red on Gram-stained smear. Larger than white blood cells. Have a single nucleus. They are an indication of a suboptimal or unacceptable specimen if present in large numbers in sputum specimens, tracheal or endotracheal aspirates, or in urine specimens.
White blood cells	12 µm		Appear pink/red on Gram-stained smear. Most often, polymorphonuclear white blood cells (PMNs). White blood cells indicate inflammation and possible infection. The direct smear examination should focus within and around these cells.
Hyphae/pseudohyphae	Varies		Appear blue on Gram-stained smear. Hyphae are tubular filamentous fungal elements, which may show branching or intertwining. Pseudohyphae are multiple buds of yeast that do not detach, thereby forming chains.
Yeast	7 µm		Appear blue on Gram-stained smear. Round to oval, often budding. About the same size as red blood cells. Generally much larger than bacteria. A few yeast may be present as normal flora in upper respiratory tract or genital tract. They may be significant if they predominate, or if budding yeast forms are seen.
Red blood cells	7µm		Appear red on Gram-stained smear Not usually considered a significant finding.