Impression Smear Agreement with Acetate Tape Preparation for Cytologic Sampling

Abstract

Cutaneous cytologic sampling techniques are used to detect bacteria, yeast, and inflammatory cells for diagnosis and therapeutic monitoring. Studies have examined slide evaluation techniques, ear swab cytology staining methods, and observer variations; few studies compare common clinical sampling techniques. The primary aim of this study was to measure detection of microorganisms and neutrophils by impression smear compared to acetate tape preparation; comparison of agreement between two acetate tape staining methods was a secondary aim. Thirty lesions consistent with superficial pyoderma were sampled via impression smear and acetate tape preparation. Acetate tape preparations were either stained with modified Romanowksy stain solutions two and three or solution three alone. Impression smears were stained in the standard manner. Bacteria, yeast, and neutrophils were evaluated using a semi-quantitative scale [0-4]. Quantities were aggregated and compared using Cohen's kappa to measure agreement between methods. When impression smears were compared to acetate tape, the lowest agreement occurred for neutrophils, with impression smears detecting more neutrophils. Comparison of acetate tape staining methods had the highest agreement for yeast detection. Sampling technique and staining method did not differ for detection of bacteria. Impression smears detected more neutrophils, and yeast detection appeared equivalent for acetate tape staining methods.

A novel cytological technique for bacterial detection on canine skin

“…The order that samples were taken is justified by the standard approach to obtaining impression smears, which involves preparation of the surface to be sampled. 9 Tape-strip followed by the skin scraping associated with specimen collection for the slurry preparation were considered to be adequate preparation for impression smear as it closely mimics the current clinical practice recommendations for readying the skin surface. 7,9,11 Future studies could take into account the order in which samples were obtained and/or obtain samples from geographically adjacent lesions of similar morphology and severity, and not from the same location, as was the case in this study.…”

“…The tape-strip preparations were stained via 10 dips each lasting 1 s in the red (eosin) reagent of a modified Wright-Giemsa stain set (Protocol Hema 3 Stat Pack, Fischer Healthcare; Federal Way, WA, USA) followed by 10 dips each lasting 1 s in the violet (thiazine) reagent of the same stain set. 8,9 The tape then was removed from the slide, rinsed via five 1 s dips into a container of clean water, gently shaken to remove excess liquid, allowed to dry and finally affixed sticky side down onto a clean glass slide. The slurry preparations were prepared for staining by first removing the slide that had been placed as a cover, being careful not to lose any collected debris.…”

“…Slurry preparation slides were stained with the complete set of modified Wright-Giemsa stains with 10 dips each lasting 1 s per reagent. [7][8][9][10] In total, the slurry preparation took 2-3 min or less to prepare. (See Supporting information Video S1 for a demonstration of the technique needed to prepare a slurry preparation sample).…”

“…The impression smears were stained with the complete set of modified Wright-Giemsa stains with 10 dips each lasting 1 s per reagent. [7][8][9][10]…”

“…7,9,10 For example, some authors recommend the use of impression smear for moist lesions and the use of tape-strip preparation for dry or seborrhoeic lesions, while other authors either make no distinction or give the opposite recommendation. 4,[8][9][10] A robust 2017 study 9 compared agreement between impression smear and tape-strip preparations, finding no differences in their ability to detect either bacterial or Malassezia organisms. Currently, there is a relative paucity of literature directly comparing cytological techniques of any kind.…”