Investigation of the use of cytobrush for cytological and bacteriological diagnosis of endometritis in mares

Combined microbial and cytological examination of uterine samples is the diagnostic mainstayof infectious endometritis in the mare [1]. Use of a single instrument to perform both samplingscould be an economical and practical alternative in the field [2]. Aims of this study were todescribe a technique for the collection and processing of endometrial samples by cytobrush(CB) for both cytological and microbiological examinations and to evaluate its feasibility,accuracy and reliability in the diagnosis of endometritis in the mare.Uterine sampling by CB was performed in 33 Standardbred mares. The first 10 mares weresampled with a double-guarded cotton swab (CS) and CB as previously described [3]. In thefield, brush was rolled onto a sterilized glass slide (FS) and then it was immersed in 4ml ofsterile saline solution. In the lab, the brush and the pellet obtained by the saline centrifugationwere rolled onto glass slides (LS and PS). Smears were evaluated for background, quality ofthe cells harvested, total cellularity and neutrophils (PMN), ratio PMN/uterine epithelial cellsand inflammatory scores. Brush and pellet were incubated in enrichment broth, whereas CSwas incubated in enrichment broth and directly plated onto blood agar plate. Cytological dataobtained by the examination of FS, LS and PS were compared; the agreement between cultureresults from CS (BCS), CB (BCB) and pellet (BBP) were evaluated.Smears from pellet (PS) were always not diagnostic. Total cellularity, neutrophils, backgroundand inflammatory scores were significantly higher in FS than in LS, whereas quality scores didnot differ.The agreement between BCS and BCB was excellent (k=1) in both positive and negativecultures; significantly more positive culture were obtained by BCB and the agreement betweenBCB and BBP was moderate (k=0.43).Sample collection by cytobrush (CB) was considered the preferred method of cytologicalsmears for use in the field [3]. Our cytological examinations on smears made using thecytobrush in the field (FS) yielded good cellularity and high reliability for diagnosis ofendometritis. Even if the use of exfoliative cytology combined with samples collection forculture is poorly described [2,4], our study showed that a double-guarded brush can be used toperform both sampling simultaneously. In order to minimize the risk of contamination a properprocedure should be used. In our results, with this procedure suitable samples forbacteriological examinations were obtained. A culture enrichment broth of both brush andpellet are recommended to ensure more information.The diagnostic interpretation of positive culture data after enrichment must be completed inaccordance with cytological results and clinical signs of the mare.