Animal Dermatology Clinic, 5610 Kearny Mesa Road, San Diego, CA, 92111, USA.
Animal Dermatology Clinic, 2965 Edinger Avenue, Tustin, CA, 92780, USA.
Vet Dermatol. 2021 Oct;32(5):448-e122. doi: 10.1111/vde.13009. Epub 2021 Aug 5.
Micro-organisms associated with canine otitis externa (OE) may cause biofilm-associated infections (BAI). A key component of biofilm is microbial aggregate and extracellular polymeric substance (EPS). Periodic acid Schiff (PAS) can stain polysaccharide EPS in human otitis media with effusion, but this has not been tested in canine OE. There is no cytological definition for microbial aggregate, and definitive methods for identifying BAI in a clinical setting in canine OE have not been defined.
To establish whether PAS stain can identify polysaccharide matrix on cytological smears; and to determine the reproducibility of identification of microbial aggregates within a discrete area of stained matrix, using paired modified Wright's and PAS-stained smears.
Forty privately-owned dogs presenting to a dermatological referral practice.
In this prospective, cross-sectional study, three investigators independently and blindly classified 40 paired modified Wright's-PAS slide sets into groups: aggregate-associated infection (AAI) and non-AAI (n = 27); and control (n = 13). Agreement between investigators for presence of AAI was measured using Fleiss' kappa statistic (FK). Agreement between investigators and dermatologists for presence of AAI upon cytological evaluation, and suspected BAI based on clinical examination, was measured using Cohen's kappa statistic.
The matrix was confirmed to stain PAS-positive. Interinvestigator agreement for AAI was very good using PAS (0.82 FK) and fair using modified-Wright's (MW) (0.33 FK). Reproducible cytological features associated with AAI were the presence of: three or more distinct aggregates (0.76 FK); discrete areas of PAS-positive matrix (0.70 FK); and the presence of high-density material (0.70 FK) using PAS stain.
PAS can stain the extracellular matrix on otic smears, and a novel protocol for reproducible identification of cytological features such as microbial aggregates has been established.
与犬外耳炎（OE）相关的微生物可能引起生物膜相关感染（BAI）。生物膜的一个关键组成部分是微生物聚集体和细胞外聚合物（EPS）。过碘酸希夫（PAS）可以染色人类中耳积液中的多糖 EPS，但尚未在犬 OE 中进行过测试。微生物聚集体没有细胞学定义，并且在犬 OE 的临床环境中确定 BAI 的明确方法尚未确定。
确定 PAS 染色是否可以识别细胞学涂片上的多糖基质；并确定在染色基质的离散区域内识别微生物聚集体的重现性，使用配对的改良 Wright's 和 PAS 染色涂片。
40 只私人拥有的犬，就诊于皮肤科转诊诊所。
在这项前瞻性、横断面研究中，三名研究人员独立且盲目地将 40 对改良 Wright's-PAS 幻灯片集分为以下组：聚集体相关感染（AAI）和非 AAI（n=27）；对照组（n=13）。使用 Fleiss' kappa 统计量（FK）衡量调查员之间存在 AAI 的一致性。使用 Cohen's kappa 统计量衡量调查员与皮肤科医生之间在细胞学评估中存在 AAI 的一致性，以及根据临床检查怀疑存在 BAI 的一致性。
基质被证实 PAS 染色阳性。使用 PAS 时，调查员之间的 AAI 一致性非常好（0.82 FK），使用改良 Wright's 时一致性为中等（0.33 FK）。与 AAI 相关的可重复的细胞学特征包括：存在三个或更多个不同的聚集体（0.76 FK）；存在离散的 PAS 阳性基质区域（0.70 FK）；使用 PAS 染色时存在高密度物质（0.70 FK）。
PAS 可以染色耳涂片的细胞外基质，并且已经建立了一种用于可重复识别微生物聚集体等细胞学特征的新方案。
