In situ hybridisation in endometrial biopsies of horses: a diagnostic approach to bacterially induced endometritis?

Jäger, Kathrin; Grafe, H. K.; Klug, E; Schoon, D.; Schoon, H-A

doi:10.21836/pem20110302

Cited by 2 publications

(4 citation statements)

References 10 publications

(12 reference statements)

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“…It is possible that the number of bacteria in our samples was not high enough for proper detection with ISH due to biofilm degradation during fixation. Additionally, Jäger et al (8) used a different probe for E. coli detection, with 23S rRNA as the target rRNA (sequence: 5′-GCA TAA GCG TCG CTG CCG-3′), which does not target all E. coli strains (23), perhaps explaining the low prevalence in that study. To the authors' knowledge, there are no previous reports on diagnosing the bacteria from equine endometrium with the probe used in the present study.…”

Section: Discussionmentioning

confidence: 94%

“…A study by Jäger et al (8) studied bacterial colonization of the equine endometrium with ISH, and detected streptococci and E. coli in the luminal epithelium and the superficial secretory ducts of the uterine glands. Biofilm plaques were not reported.…”

Section: Discussionmentioning

confidence: 99%

“…Histopathology is the golden standard for the diagnosis of endometritis, especially in mares suffering from subclinical endometritis (6,7). The most common pathogenic bacteria isolated are β-hemolytic streptococci and E. coli (7,8) but in a recent study by Teixeira-Soares et al (6), Staphylococcus spp. was found more frequently than Streptococcus spp.…”

Section: Introductionmentioning

confidence: 99%

“…It is not well established whether persistent or latent E. coliinvasion occurs in the equine endometrium. By using in situ hybridization, Jäger et al (8) found E. coli RNA in endometrial biopsies in only 4% of E. coli culture positive mares (n = 99). In their study, 36% of the E. coli culture positive mares had detectable endometrial inflammation in the uterine biopsy, and no inflammation was detected in the mares in which E. coli could be demonstrated with in situ hybridization.…”

Section: Introductionmentioning

confidence: 99%

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RNA in situ hybridization of Escherichia coli in equine endometrial biopsies

Tukia¹,

Hallman²,

Penttilä³

et al. 2023

Front. Vet. Sci.

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Endometritis is one of the major causes of infertility in mares. Escherichia coli and β-haemolytic streptococci are among the bacterial species most frequently isolated from the equine uterus. Some bacteria such as β-hemolytic streptococci, can persist in dormant forms and cause prolonged, latent or recurrent infections. Dormant bacteria may be present despite negative bacterial cultures, and they are resistant to antimicrobial treatment due to their resting metabolic state. The purpose of this study was to study formalin-fixed paraffin-embedded equine endometrial biopsies for the presence and localization of E. coli—bacteria, with a chromogenic RNAscope®-method for detection of E. coli-related 16S ribosomal RNA. Hematoxylin-eosin—stained endometrial biopsies were evaluated to determine the level of inflammation and degeneration. During estrus, samples were taken for endometrial culture and cytology with a double-guarded uterine swab. The samples included eight samples with moderate to severe endometrial inflammation detected in endometrial histopathology, and growth of E. coli in bacterial culture, six samples with moderate to severe endometrial inflammation but negative bacterial culture, and five samples with no endometrial pathology (grade I endometrial biopsy, negative endometrial culture and cytology) serving as controls. Positive and negative control probes were included in the RNA in situ hybridization, and results were confirmed with a fluorescence detection method (fluorescence in situ hybridization). Only unspecific signals of limited size and frequency of occurrence were detected in all samples, with random localization in the endometrium. No samples contained rod-shaped signals corresponding to bacterial findings. In conclusion, there was no evidence of bacterial invasion in the endometrium regardless of the inflammatory status of the biopsy or previous bacterial culture results. According to these findings on a small number of samples, invasion of E. coli is not a common finding in the lamina propria of mares, but these bacteria may also evade detection due to localized foci of infections, or supra-epithelial localization under the cover of biofilm. These bacteria and biofilm covering the epithelium may also be lost during formalin-fixation and processing.

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%